This directory contains Device Tree overlays. Device Tree makes it possible to support many hardware configurations with a single kernel and without the need to explicitly load or blacklist kernel modules. Note that this isn't a "pure" Device Tree configuration (c.f. MACH_BCM2835) - some on-board devices are still configured by the board support code, but the intention is to eventually reach that goal.
此目录包含设备树覆盖。设备树使用单个内核即可支持许多硬件配置，而无需显式加载或将内核模块列入黑名单。请注意，这不是“纯”设备树配置（参见MACH_BCM2835）-某些板载设备仍通过板支持代码进行配置，但其目的是最终达到该目标。
On Raspberry Pi, Device Tree usage is controlled from /boot/config.txt. By default, the Raspberry Pi kernel boots with device tree enabled. You can completely disable DT usage (for now) by adding:
device_tree=to your config.txt, which should cause your Pi to revert to the old way of doing things after a reboot.
在树莓派上，设备树的使用由/boot/config.txt控制。默认情况下，树莓派内核在启用设备树的情况下启动。您可以通过添加以下命令到你的config.txt来完全禁用设备树的使用（暂时），这将导致您的Pi在重启后恢复为旧的工作方式。
In /boot you will find a .dtb for each base platform. This describes the hardware that is part of the Raspberry Pi board. The loader (start.elf and its siblings) selects the .dtb file appropriate for the platform by name, and reads it into memory. At this point, all of the optional interfaces (i2c, i2s, spi) are disabled, but they can be enabled using Device Tree parameters:
dtparam=i2c=on,i2s=on,spi=on
在/boot中，您将找到每个基本平台的.dtb。本节描述了树莓派板上的硬件组成部分。加载程序（start.elf及其兄弟姐妹）通过名称选择适用于平台的.dtb文件，并将其读入内存。此时，所有可选接口（i2c，i2s，spi）均已禁用，但可以使用设备树参数启用它们：
However, this shouldn't be necessary in many use cases because loading an overlay that requires one of those interfaces will cause it to be enabled automatically, and it is advisable to only enable interfaces if they are needed.
但是，在许多用例中这不是必需的，因为加载需要这些接口之一的叠加层会导致它自动启用，建议仅在需要时启用它们。
Configuring additional, optional hardware is done using Device Tree overlays (see below).
使用设备树覆盖图（请参见下文）完成其他可选硬件的配置。
GPIO numbering uses the hardware pin numbering scheme (aka BCM scheme) and not the physical pin numbers.
GPIO编号使用硬件引脚编号方案（也称为BCM方案），而不是物理引脚编号。
The Advanced Options section of the raspi-config utility can enable and disable Device Tree use, as well as toggling the I2C and SPI interfaces. Note that it is possible to both enable an interface and blacklist the driver, if for some reason you should want to defer the loading.
raspi-config是实用程序的“高级选项”部分可以启用和禁用设备树的使用，以及切换I2C和SPI接口。请注意，如果出于某种原因您应该推迟加载，则既可以启用接口也可以将驱动程序列入黑名单。
As well as describing the hardware, Device Tree also gives enough information to allow suitable driver modules to be located and loaded, with the corollary that unneeded modules are not loaded. As a result it should be possible to remove lines from
/etc/modules, and/etc/modprobe.d/raspi-blacklist.confcan have its contents deleted (or commented out).
除了描述硬件外，设备树还提供了足够的信息以允许定位和加载合适的驱动程序模块，从而不加载不需要的模块。因此，可以从/etc/modules和/etc/modprobe.d/raspi-blacklist.conf中可以删除（或注释掉）其内容。
Overlays are loaded using the "dtoverlay" config.txt setting. As an example, consider I2C Real Time Clock drivers. In the pre-DT world these would be loaded by writing a magic string comprising a device identifier and an I2C address to a special file in
/sys/class/i2c-adapter, having first loaded the driver for the I2C interface and the RTC device - something like this:
使用dtoverlay中的config.txt的设置加载Overlays。例如，考虑I2C实时时钟驱动程序。在预设备树的环境下，首先加载I2C接口和RTC设备的驱动程序，可以通过将包含设备标识符和I2C地址的魔法字符串写入/sys/class/i2c-adapter的特殊文件中来加载这些文件-如下所示：
modprobe i2c-bcm2835
modprobe rtc-ds1307
echo ds1307 0x68 > /sys/class/i2c-adapter/i2c-1/new_device
With DT enabled, this becomes a line in config.txt:
启用DT后，这将成为config.txt中的一行：
dtoverlay=i2c-rtc,ds1307
This causes the file /boot/overlays/i2c-rtc.dtbo to be loaded and a "node" describing the DS1307 I2C device to be added to the Device Tree for the Pi. By default it usees address 0x68, but this can be modified with an additional DT parameter:
这将导致文件/boot/overlays/i2c-rtc.dtbo被加载，并将描述DS1307 I2C设备的“节点”添加到树莓派的设备树中。默认情况下，它使用地址0x68，但是可以使用附加的DT参数对其进行修改：
dtoverlay=i2c-rtc,ds1307,addr=0x68
Parameters usually have default values, although certain parameters are mandatory. See the list of overlays below for a description of the parameters and their defaults.
尽管某些参数是必需的，但参数通常具有默认值。有关参数及其默认值的说明，请参见下面的overlays列表。
Recent overlays have been designed in a more general way, so that they can be adapted to hardware by changing their parameters. When you have additional hardware with more than one device of a kind, you end up using the same overlay multiple times with other parameters, e.g.
最近的Overlays已经以更通用的方式进行了设计，因此可以通过更改其参数将其应用于硬件。当您拥有带有一种以上设备的其他硬件时，最终会多次使用相同的Overlay以及其他参数，例如：
# 2 CAN FD interfaces on spi but with different pins spi上的CAN FD接口，但引脚不同
dtoverlay=mcp251xfd,spi0-0,interrupt=25
dtoverlay=mcp251xfd,spi0-1,interrupt=24
# a realtime clock on i2c i2c上的实时时钟
dtoverlay=i2c-rtc,pcf85063
While this approach does work, it requires knowledge about the hardware design. It is more feasible to simplify things for the end user by providing a single overlay as it is done the traditional way.
尽管此方法确实有效，但它需要有关硬件设计的知识。与传统方式一样，通过提供单个overlay来简化最终用户的工作更为可行。
A new overlay can be generated by using ovmerge utility. LINK
新的overlay可以使用ovmerge utility程序生成。链接
To generate an overlay for the above configuration we pass the configuration to ovmerge and add the -c flag.
要为上述配置生成overlay，我们将配置传递给ovmerge并添加-c标志。
ovmerge -c mcp251xfd-overlay.dts,spi0-0,interrupt=25 mcp251xfd-overlay.dts,spi0-1,interrupt=24 i2c-rtc-overlay.dts,pcf85063 >> merged-overlay.dts
The -c option writes the command above as a comment into the overlay as a marker that this overlay is generated and how it was generated. After compiling the overlay it can be loaded in a single line.
-c选项将上面的命令作为注释写入到overlay中，作为该overlay的生成方式和生成方式的标记。编译overlay后，可以将其加载到一行中。
dtoverlay=merged
It does the same as the original configuration but without parameters.
它与原始配置相同，但没有参数。
N.B. When editing this file, please preserve the indentation levels to make it simple to parse programmatically. NO HARD TABS.
N.B.编辑此文件时，请保留缩进级别，以使其易于以编程方式进行解析。没有硬标签。
Name: <The base DTB>
Info: Configures the base Raspberry Pi hardware # 配置树莓派的基础硬件
Load: <loaded automatically> # 自动加载
Params:
ant1 Select antenna 1 (default). CM4 only.
# 选择天线1（默认）。仅支持CM4。
ant2 Select antenna 2. CM4 only.
# 选择天线2。仅支持CM4。
noant Disable both antennas. CM4 only.
# 禁用两个天线。仅支持CM4
audio Set to "on" to enable the onboard ALSA audio interface (default "off")
# 设置为“开”以启用板载ALSA音频接口（默认为“关”）
axiperf Set to "on" to enable the AXI bus performancemonitors.
# 设置为“on”以启用AXI总线性能监视器。
See /sys/kernel/debug/raspberrypi_axi_monitor for the results.
# 有关结果，请参见/sys/kernel/debug/raspberrypi_axi_monitor。
eee Enable Energy Efficient Ethernet support for compatible devices (default "on").
# 为兼容设备启用节能以太网支持（默认为“on”）。
See also "tx_lpi_timer". Pi3B+ only.
# 另请参见“ tx_lpi_timer”。仅支持Pi3B +。
eth_downshift_after Set the number of auto-negotiation failures after which the 1000Mbps modes are disabled.
# 设置自动协商失败的次数，此后禁用1000Mbps模式。
Legal values are 2, 3, 4, 5 and 0, where 0 means never downshift (default 2). Pi3B+ only.
# 有效值为2、3、4、5和0，其中0表示永不降档（默认为2）。仅支持Pi3B +。
eth_led0 Set mode of LED0 - amber on Pi3B+ (default "1"),green on Pi4 (default "0").
# 设置LED0的模式-Pi3B +上为琥珀色（默认为“1”），Pi4上为绿色（默认为“0”）。
The legal values are: # 有效值如下
Pi3B+
0=link/activity 1=link1000/activity 2=link100/activity
3=link10/activity 4=link100/1000/activity 5=link10/1000/activity
6=link10/100/activity 14=off 15=on
Pi4
0=Speed/Activity 1=Speed 2=Flash activity
3=FDX 4=Off 5=On 6=Alt
7=Speed/Flash 8=Link 9=Activity
eth_led1 Set mode of LED1 - green on Pi3B+ (default "6"), amber on Pi4 (default "8"). See eth_led0 for legal values.
# 设置LED1的模式-Pi3B +上为绿色（默认为“6”），Pi4上为琥珀色（默认为“8”）。有关有效值，请参见eth_led0。
eth_max_speed Set the maximum speed a link is allowed to negotiate. Legal values are 10, 100 and 1000 (default 1000). Pi3B+ only.
# 设置允许链接协商的最大速度。有效值为10、100和1000（默认值为1000）。仅支持Pi3B+。
i2c_arm Set to "on" to enable the ARM's i2c interface (default "off")
# 设置为“ on”以启用ARM的i2c接口（默认为“ off”）
i2c_vc Set to "on" to enable the i2c interface usually reserved for the VideoCore processor (default "off")
# 设置为“ on”以启用i2c接口，通常为VideoCore处理器保留（默认为“关闭”）
i2c An alias for i2c_arm
# i2c_arm的别名
i2c_arm_baudrate Set the baudrate of the ARM's i2c interface (default "100000")
# 设置ARM的i2c接口的波特率（默认为“100000”）
i2c_vc_baudrate Set the baudrate of the VideoCore i2c interface (default "100000")
# 设置VideoCore i2c接口的波特率（默认为“ 100000”）
i2c_baudrate An alias for i2c_arm_baudrate
# i2c_arm_baudrate的别名
i2s Set to "on" to enable the i2s interface (default "off")
# 设置为“on”以启用i2s接口（默认为“off”）
krnbt Set to "on" to enable autoprobing of Bluetooth driver without need of hciattach/btattach (default "off")
# 设置为“on”以启用对蓝牙驱动程序的自动探测，而无需进行hciattach/btattach（默认为“off”）
krnbt_baudrate Set the baudrate of the PL011 UART when used with krnbt=on
# 与 krnbt=on 一起使用时，设置PL011 UART的波特率
spi Set to "on" to enable the spi interfaces (default "off")
# 设置为“ on”以启用spi接口（默认为“ off”）
spi_dma4 Use to enable 40-bit DMA on spi interfaces (the assigned value doesn't matter)(2711 only)
# 用于在spi接口上启用40位DMA（分配的值无关紧要）（仅支持2711）
random Set to "on" to enable the hardware random number generator (default "on")
# 设置为“on”以启用硬件随机数生成器（默认为“on”）
sd_overclock Clock (in MHz) to use when the MMC framework requests 50MHz
# MMC框架请求50MHz时要使用的时钟（以MHz为单位）
sd_poll_once Looks for a card once after booting. Useful for network booting scenarios to avoid the overhead of continuous polling. N.B. Using this option restricts the system to using a single card per boot (or none at all). (default off)
# 引导后查找一次卡。对于网络启动方案很有用，可避免连续轮询的开销。N.B.使用此选项将系统限制为每次引导仅使用一张卡（或完全不使用）。（默认关闭）
sd_force_pio Disable DMA support for SD driver (default off)
# 禁用对SD驱动程序的DMA支持（默认关闭）
sd_pio_limit Number of blocks above which to use DMA for SD card (default 1)
# 将DMA用于SD卡的块数（默认为1）
sd_debug Enable debug output from SD driver (default off)
# 启用SD驱动程序的调试输出（默认关闭）
sdio_overclock Clock (in MHz) to use when the MMC framework requests 50MHz for the SDIO/WiFi interface.
# MMC框架为SDIO / WiFi接口请求50MHz时使用的时钟（以MHz为单位）。
tx_lpi_timer Set the delay in microseconds between going idle and entering the low power state (default 600). Requires EEE to be enabled - see "eee".
# 设置从空闲到进入低功耗状态之间的延迟(以微秒为单位)(默认为600)。需要启用EEE-请参阅“eee”。
uart0 Set to "off" to disable uart0 (default "on")
# 设置为“关”以禁用uart0（默认为“开”）
uart1 Set to "on" or "off" to enable or disable uart1 (default varies)
# 设置为“on”或“off”以启用或禁用uart1（默认值有所不同）
watchdog Set to "on" to enable the hardware watchdog (default "off")
# 设置为“开”以启用硬件看门狗（默认为“关”）
act_led_trigger Choose which activity the LED tracks. Use "heartbeat" for a nice load indicator.(default "mmc")
# 选择LED跟踪的活动。使用“心跳”作为良好的负载指示器。（默认为“mmc”）
act_led_activelow Set to "on" to invert the sense of the LED (default "off")
# 设置为“开”以反转LED的感觉（默认为“关”）。
N.B. For Pi 3B, 3B+, 3A+ and 4B, use the act-led overlay.
# 对于Pi 3B,3B+,3A+和4B，请使用act-led overlay。
act_led_gpio Set which GPIO to use for the activity LED (in case you want to connect it to an external device)
# 设置用于活动LED的GPIO（如果要将其连接到外部设备）
(default "16" on a non-Plus board, "47" on a Plus or Pi 2)
# （非Plus板上的默认值为“ 16”，Plus或Pi 2上的默认值为“ 47”）
N.B. For Pi 3B, 3B+, 3A+ and 4B, use the act-led overlay.
# N.B。对于Pi 3B,3B+,3A+和4B，请使用act-led overlay。
pwr_led_trigger
pwr_led_activelow
pwr_led_gpio
As for act_led_*, but using the PWR LED. Not available on Model A/B boards.
# 与act_led_*一样，但使用PWR LED。A/B型板上不可用。N.B. It is recommended to only enable those interfaces that are needed. Leaving all interfaces enabled can lead to unwanted behaviour (i2c_vc interfering with Pi Camera, I2S and SPI hogging GPIO pins, etc.) Note also that i2c, i2c_arm and i2c_vc are aliases for the physical interfaces i2c0 and i2c1. Use of the numeric variants is still possible but deprecated because the ARM/VC assignments differ between board revisions. The same board-specific mapping applies to i2c_baudrate, and the other i2c baudrate parameters.
N.B.建议仅启用所需的那些接口。使所有接口保持启用状态可能会导致不良行为（i2c_vc干扰Pi Camera，I2S和SPI占用GPIO引脚等）。另请注意，i2c,i2c_arm和i2c_vc是物理接口i2c0和i2c1的别名。仍然可以使用数字变量，但由于ARM/VC分配在板修订版之间不同，因此不建议使用。相同的特定于板的映射适用于i2c_baudrate和其他i2c波特率参数。
Name: act-led
Info: Pi 3B, 3B+, 3A+ and 4B use a GPIO expander to drive the LEDs which can only be accessed from the VPU. There is a special driver for this with a separate DT node, which has the unfortunate consequence of breaking the act_led_gpio and act_led_activelow dtparams.This overlay changes the GPIO controller back to the standard one and restores the dtparams.
# Pi 3B,3B+,3A+和4B使用GPIO扩展器来驱动只能通过VPU访问的LED。为此，有一个特殊的驱动程序带有单独的设备树节点，不幸的结果是破坏了act_led_gpio和act_led_activelow dtparams。此覆盖将GPIO控制器改回标准控制器，并恢复dtparams。
Load: dtoverlay=act-led,<param>=<val>
Params: activelow Set to "on" to invert the sense of the LED (default "off")
# 设置为“开”以反转LED的亮度（默认为“关”）
gpio Set which GPIO to use for the activity LED (in case you want to connect it to an external device) REQUIRED
# 设置要用于活动LED的GPIO（如果您想将其连接到外部设备）
Name: adafruit18
Info: Overlay for the SPI-connected Adafruit 1.8" display (based on the ST7735R chip). It includes support for the "green tab" version.
# 用于SPI连接的Adafruit 1.8''显示屏（基于ST7735R芯片）的覆盖。它包括对“绿色选项卡”版本的支持。
Load: dtoverlay=adafruit18,<param>=<val>
Params: green Use the adafruit18_green variant. # 使用adafruit18_green变体。
rotate Display rotation {0,90,180,270} # 旋转显示旋转{0,90,180,270}
speed SPI bus speed in Hz (default 4000000) # SPI总线速度（Hz）（默认4000000）
fps Display frame rate in Hz # 以Hz为单位显示帧频
bgr Enable BGR mode (default off) # 启用BGR模式（默认关闭）
debug Debug output level {0-7} # 调试输出级别{0-7}
dc_pin GPIO pin for D/C (default 24) # D/C的GPIO引脚（默认为24）
reset_pin GPIO pin for RESET (default 25) # RESET的GPIO引脚（默认25）
led_pin GPIO used to control backlight (default 18) # GPIO用于控制背光（默认值为18）
Name: adau1977-adc
Info: Overlay for activation of ADAU1977 ADC codec over I2C for control and I2S for data.
# 用于控制的I2C和数据的I2S激活ADAU1977 ADC编解码器的overlay。
Load: dtoverlay=adau1977-adc
Params: <None>
Name: adau7002-simple
Info: Overlay for the activation of ADAU7002 stereo PDM to I2S converter.
Load: dtoverlay=adau7002-simple,<param>=<val>
Params: card-name Override the default, "adau7002", card name.
Name: ads1015
Info: Overlay for activation of Texas Instruments ADS1015 ADC over I2C
Load: dtoverlay=ads1015,<param>=<val>
Params: addr I2C bus address of device. Set based on how the addr pin is wired. (default=0x48 assumes addr is pulled to GND)
cha_enable Enable virtual channel a. (default=true)
cha_cfg Set the configuration for virtual channel a.(default=4 configures this channel for the voltage at A0 with respect to GND)
cha_datarate Set the datarate (samples/sec) for this channel. (default=4 sets 1600 sps)
cha_gain Set the gain of the Programmable Gain Amplifier for this channel. (default=2 sets the full scale of the channel to 2.048 Volts)
Channel (ch) parameters can be set for each enabled channel. A maximum of 4 channels can be enabled (letters a thru d). For more information refer to the device datasheet at: http://www.ti.com/lit/ds/symlink/ads1015.pdf
可以为每个启用的通道设置通道（ch）参数。最多可以启用4个通道（字母a至d）。有关更多信息，请参见以下设备的数据表：【ADS1015】
Name: ads1115
Info: Texas Instruments ADS1115 ADC
Load: dtoverlay=ads1115,<param>[=<val>]
Params: addr I2C bus address of device. Set based on how the
addr pin is wired. (default=0x48 assumes addr
is pulled to GND)
cha_enable Enable virtual channel a.
cha_cfg Set the configuration for virtual channel a.
(default=4 configures this channel for the
voltage at A0 with respect to GND)
cha_datarate Set the datarate (samples/sec) for this channel.
(default=7 sets 860 sps)
cha_gain Set the gain of the Programmable Gain
Amplifier for this channel. (Default 1 sets the
full scale of the channel to 4.096 Volts)
Channel parameters can be set for each enabled channel.A maximum of 4 channels can be enabled (letters a thru d).For more information refer to the device datasheet at: 【ADS1115】
Name: ads7846
Info: ADS7846 Touch controller
Load: dtoverlay=ads7846,<param>=<val>
Params: cs SPI bus Chip Select (default 1)
speed SPI bus speed (default 2MHz, max 3.25MHz)
penirq GPIO used for PENIRQ. REQUIRED
penirq_pull Set GPIO pull (default 0=none, 2=pullup)
swapxy Swap x and y axis
xmin Minimum value on the X axis (default 0)
ymin Minimum value on the Y axis (default 0)
xmax Maximum value on the X axis (default 4095)
ymax Maximum value on the Y axis (default 4095)
pmin Minimum reported pressure value (default 0)
pmax Maximum reported pressure value (default 65535)
xohms Touchpanel sensitivity (X-plate resistance)
(default 400)
penirq is required and usually xohms (60-100) has to be set as well.
Apart from that, pmax (255) and swapxy are also common.
The rest of the calibration can be done with xinput-calibrator.
See: github.com/notro/fbtft/wiki/FBTFT-on-Raspian
Device Tree binding document:
www.kernel.org/doc/Documentation/devicetree/bindings/input/ads7846.txt
Name: adv7282m
Info: Analog Devices ADV7282M analogue video to CSI2 bridge.
Uses Unicam1, which is the standard camera connector on most Pi
variants.
Load: dtoverlay=adv7282m,<param>=<val>
Params: addr Overrides the I2C address (default 0x21)
Name: adv728x-m
Info: Analog Devices ADV728[0|1|2]-M analogue video to CSI2 bridges.
This is a wrapper for adv7282m, and defaults to ADV7282M.
Load: dtoverlay=adv728x-m,<param>=<val>
Params: addr Overrides the I2C address (default 0x21)
adv7280m Select ADV7280-M.
adv7281m Select ADV7281-M.
adv7281ma Select ADV7281-MA.
Name: akkordion-iqdacplus
Info: Configures the Digital Dreamtime Akkordion Music Player (based on the
OEM IQAudIO DAC+ or DAC Zero module).
Load: dtoverlay=akkordion-iqdacplus,<param>=<val>
Params: 24db_digital_gain Allow gain to be applied via the PCM512x codec
Digital volume control. Enable with
dtoverlay=akkordion-iqdacplus,24db_digital_gain
(The default behaviour is that the Digital
volume control is limited to a maximum of
0dB. ie. it can attenuate but not provide
gain. For most users, this will be desired
as it will prevent clipping. By appending
the 24db_digital_gain parameter, the Digital
volume control will allow up to 24dB of
gain. If this parameter is enabled, it is the
responsibility of the user to ensure that
the Digital volume control is set to a value
that does not result in clipping/distortion!)
Name: allo-boss-dac-pcm512x-audio
Info: Configures the Allo Boss DAC audio cards.
Load: dtoverlay=allo-boss-dac-pcm512x-audio,<param>
Params: 24db_digital_gain Allow gain to be applied via the PCM512x codec
Digital volume control. Enable with
"dtoverlay=allo-boss-dac-pcm512x-audio,
24db_digital_gain"
(The default behaviour is that the Digital
volume control is limited to a maximum of
0dB. ie. it can attenuate but not provide
gain. For most users, this will be desired
as it will prevent clipping. By appending
the 24db_digital_gain parameter, the Digital
volume control will allow up to 24dB of
gain. If this parameter is enabled, it is the
responsibility of the user to ensure that
the Digital volume control is set to a value
that does not result in clipping/distortion!)
slave Force Boss DAC into slave mode, using Pi a
master for bit clock and frame clock. Enable
with "dtoverlay=allo-boss-dac-pcm512x-audio,
slave"
Name: allo-boss2-dac-audio
Info: Configures the Allo Boss2 DAC audio card
Load: dtoverlay=allo-boss2-dac-audio
Params: <None>
Name: allo-digione
Info: Configures the Allo Digione audio card
Load: dtoverlay=allo-digione
Params: <None>
Name: allo-katana-dac-audio
Info: Configures the Allo Katana DAC audio card
Load: dtoverlay=allo-katana-dac-audio
Params: <None>
Name: allo-piano-dac-pcm512x-audio
Info: Configures the Allo Piano DAC (2.0/2.1) audio cards.
(NB. This initial support is for 2.0 channel audio ONLY! ie. stereo.
The subwoofer outputs on the Piano 2.1 are not currently supported!)
Load: dtoverlay=allo-piano-dac-pcm512x-audio,<param>
Params: 24db_digital_gain Allow gain to be applied via the PCM512x codec
Digital volume control.
(The default behaviour is that the Digital
volume control is limited to a maximum of
0dB. ie. it can attenuate but not provide
gain. For most users, this will be desired
as it will prevent clipping. By appending
the 24db_digital_gain parameter, the Digital
volume control will allow up to 24dB of
gain. If this parameter is enabled, it is the
responsibility of the user to ensure that
the Digital volume control is set to a value
that does not result in clipping/distortion!)
Name: allo-piano-dac-plus-pcm512x-audio
Info: Configures the Allo Piano DAC (2.1) audio cards.
Load: dtoverlay=allo-piano-dac-plus-pcm512x-audio,<param>
Params: 24db_digital_gain Allow gain to be applied via the PCM512x codec
Digital volume control.
(The default behaviour is that the Digital
volume control is limited to a maximum of
0dB. ie. it can attenuate but not provide
gain. For most users, this will be desired
as it will prevent clipping. By appending
the 24db_digital_gain parameter, the Digital
volume control will allow up to 24dB of
gain. If this parameter is enabled, it is the
responsibility of the user to ensure that
the Digital volume control is set to a value
that does not result in clipping/distortion!)
glb_mclk This option is only with Kali board. If enabled,
MCLK for Kali is used and PLL is disabled for
better voice quality. (default Off)
Name: anyspi
Info: Universal device tree overlay for SPI devices
Just specify the SPI address and device name ("compatible" property).
This overlay lacks any device-specific parameter support!
For devices on spi1 or spi2, the interfaces should be enabled
with one of the spi1-1/2/3cs and/or spi2-1/2/3cs overlays.
Examples:
1. SPI NOR flash on spi0.1, maximum SPI clock frequency 45MHz:
dtoverlay=anyspi:spi0-1,dev="jedec,spi-nor",speed=45000000
2. MCP3204 ADC on spi1.2, maximum SPI clock frequency 500kHz:
dtoverlay=anyspi:spi1-2,dev="microchip,mcp3204"
Load: dtoverlay=anyspi,<param>=<val>
Params: spi<n>-<m> Configure device at spi<n>, cs<m>
(boolean, required)
dev Set device name to search compatible module
(string, required)
speed Set SPI clock frequency in Hz
(integer, optional, default 500000)
Name: apds9960
Info: Configures the AVAGO APDS9960 digital proximity, ambient light, RGB and
gesture sensor
Load: dtoverlay=apds9960,<param>=<val>
Params: gpiopin GPIO used for INT (default 4)
noints Disable the interrupt GPIO line.
Name: applepi-dac
Info: Configures the Orchard Audio ApplePi-DAC audio card
Load: dtoverlay=applepi-dac
Params: <None>
Name: at86rf233
Info: Configures the Atmel AT86RF233 802.15.4 low-power WPAN transceiver,
connected to spi0.0
Load: dtoverlay=at86rf233,<param>=<val>
Params: interrupt GPIO used for INT (default 23)
reset GPIO used for Reset (default 24)
sleep GPIO used for Sleep (default 25)
speed SPI bus speed in Hz (default 3000000)
trim Fine tuning of the internal capacitance
arrays (0=+0pF, 15=+4.5pF, default 15)
Name: audioinjector-addons
Info: Configures the audioinjector.net audio add on soundcards
Load: dtoverlay=audioinjector-addons,<param>=<val>
Params: non-stop-clocks Keeps the clocks running even when the stream is paused or stopped (default off)
Name: audioinjector-isolated-soundcard
Info: Configures the audioinjector.net isolated soundcard
Load: dtoverlay=audioinjector-isolated-soundcard
Params: <None>
Name: audioinjector-ultra
Info: Configures the audioinjector.net ultra soundcard
Load: dtoverlay=audioinjector-ultra
Params: <None>
Name: audioinjector-wm8731-audio
Info: Configures the audioinjector.net audio add on soundcard
Load: dtoverlay=audioinjector-wm8731-audio
Params: <None>
Name: audiosense-pi
Info: Configures the audiosense-pi add on soundcard
For more information refer to https://gitlab.com/kakar0t/audiosense-pi
Load: dtoverlay=audiosense-pi
Params: <None>
Name: audremap
Info: Switches PWM sound output to GPIOs on the 40-pin header
Load: dtoverlay=audremap,<param>=<val>
Params: swap_lr Reverse the channel allocation, which will also
swap the audio jack outputs (default off)
enable_jack Don't switch off the audio jack output
(default off)
pins_12_13 Select GPIOs 12 & 13 (default)
pins_18_19 Select GPIOs 18 & 19
Name: balena-fin
Info: Overlay that enables WiFi, Bluetooth and the GPIO expander on the balenaFin carrier board for the Raspberry Pi Compute Module 3/3+ Lite.
Load: dtoverlay=balena-fin
Params: <None>
Name: bmp085_i2c-sensor
Info: This overlay is now deprecated - see i2c-sensor
Load: <Deprecated>
Name: cma
Info: Set custom CMA sizes, only use if you know what you are doing, might
clash with other overlays like vc4-fkms-v3d and vc4-kms-v3d.
Load: dtoverlay=cma,<param>=<val>
Params: cma-512 CMA is 512MB (needs 1GB)
cma-448 CMA is 448MB (needs 1GB)
cma-384 CMA is 384MB (needs 1GB)
cma-320 CMA is 320MB (needs 1GB)
cma-256 CMA is 256MB (needs 1GB)
cma-192 CMA is 192MB (needs 1GB)
cma-128 CMA is 128MB
cma-96 CMA is 96MB
cma-64 CMA is 64MB
cma-size CMA size in bytes, 4MB aligned
cma-default Use upstream's default value
Name: dht11
Info: Overlay for the DHT11/DHT21/DHT22 humidity/temperature sensors, Also sometimes found with the part number(s) AM230x.
Load: dtoverlay=dht11,<param>=<val>
Params: gpiopin GPIO connected to the sensor's DATA output.
(default 4)
Name: dionaudio-loco
Info: Configures the Dion Audio LOCO DAC-AMP
Load: dtoverlay=dionaudio-loco
Params: <None>
Name: dionaudio-loco-v2
Info: Configures the Dion Audio LOCO-V2 DAC-AMP
Load: dtoverlay=dionaudio-loco-v2,<param>=<val>
Params: 24db_digital_gain Allow gain to be applied via the PCM512x codec
Digital volume control. Enable with
"dtoverlay=hifiberry-dacplus,24db_digital_gain"
(The default behaviour is that the Digital
volume control is limited to a maximum of
0dB. ie. it can attenuate but not provide
gain. For most users, this will be desired
as it will prevent clipping. By appending
the 24dB_digital_gain parameter, the Digital
volume control will allow up to 24dB of
gain. If this parameter is enabled, it is the
responsibility of the user to ensure that
the Digital volume control is set to a value
that does not result in clipping/distortion!)
Name: disable-bt
Info: Disable onboard Bluetooth on Pi 3B, 3B+, 3A+, 4B and Zero W, restoring
UART0/ttyAMA0 over GPIOs 14 & 15.
N.B. To disable the systemd service that initialises the modem so it
doesn't use the UART, use 'sudo systemctl disable hciuart'.
Load: dtoverlay=disable-bt
Params: <None>
Name: disable-wifi
Info: Disable onboard WiFi on Pi 3B, 3B+, 3A+, 4B and Zero W.
Load: dtoverlay=disable-wifi
Params: <None>
Name: dpi18
Info: Overlay for a generic 18-bit DPI display
This uses GPIOs 0-21 (so no I2C, uart etc.), and activates the output
2-3 seconds after the kernel has started.
Load: dtoverlay=dpi18
Params: <None>
Name: dpi24
Info: Overlay for a generic 24-bit DPI display
This uses GPIOs 0-27 (so no I2C, uart etc.), and activates the output
2-3 seconds after the kernel has started.
Load: dtoverlay=dpi24
Params: <None>
Name: draws
Info: Configures the NW Digital Radio DRAWS Hat
The board includes an ADC to measure various board values and also
provides two analog user inputs on the expansion header. The ADC
can be configured for various sample rates and gain values to adjust
the input range. Tables describing the two parameters follow.
ADC Gain Values:
0 = +/- 6.144V
1 = +/- 4.096V
2 = +/- 2.048V
3 = +/- 1.024V
4 = +/- 0.512V
5 = +/- 0.256V
6 = +/- 0.256V
7 = +/- 0.256V
ADC Datarate Values:
0 = 128sps
1 = 250sps
2 = 490sps
3 = 920sps
4 = 1600sps (default)
5 = 2400sps
6 = 3300sps
7 = 3300sps
Load: dtoverlay=draws,<param>=<val>
Params: draws_adc_ch4_gain Sets the full scale resolution of the ADCs
input voltage sensor (default 1)
draws_adc_ch4_datarate Sets the datarate of the ADCs input voltage
sensor
draws_adc_ch5_gain Sets the full scale resolution of the ADCs
5V rail voltage sensor (default 1)
draws_adc_ch5_datarate Sets the datarate of the ADCs 4V rail voltage
sensor
draws_adc_ch6_gain Sets the full scale resolution of the ADCs
AIN2 input (default 2)
draws_adc_ch6_datarate Sets the datarate of the ADCs AIN2 input
draws_adc_ch7_gain Sets the full scale resolution of the ADCs
AIN3 input (default 2)
draws_adc_ch7_datarate Sets the datarate of the ADCs AIN3 input
alsaname Name of the ALSA audio device (default "draws")
Name: dwc-otg
Info: Selects the dwc_otg USB controller driver which has fiq support. This
is the default on all except the Pi Zero which defaults to dwc2.
Load: dtoverlay=dwc-otg
Params: <None>
Name: dwc2
Info: Selects the dwc2 USB controller driver
Load: dtoverlay=dwc2,<param>=<val>
Params: dr_mode Dual role mode: "host", "peripheral" or "otg"
g-rx-fifo-size Size of rx fifo size in gadget mode
g-np-tx-fifo-size Size of non-periodic tx fifo size in gadget
mode
[ The ds1307-rtc overlay has been deleted. See i2c-rtc. ]
Name: edt-ft5406
Info: Overlay for the EDT FT5406 touchscreen on the CSI/DSI I2C interface.
This works with the Raspberry Pi 7" touchscreen when not being polled
by the firmware.
You MUST use either "disable_touchscreen=1" or "ignore_lcd=1" in
config.txt to stop the firmware polling the touchscreen.
Load: dtoverlay=edt-ft5406,<param>=<val>
Params: sizex Touchscreen size x (default 800)
sizey Touchscreen size y (default 480)
invx Touchscreen inverted x axis
invy Touchscreen inverted y axis
swapxy Touchscreen swapped x y axis
Name: enc28j60
Info: Overlay for the Microchip ENC28J60 Ethernet Controller on SPI0
Load: dtoverlay=enc28j60,<param>=<val>
Params: int_pin GPIO used for INT (default 25)
speed SPI bus speed (default 12000000)
Name: enc28j60-spi2
Info: Overlay for the Microchip ENC28J60 Ethernet Controller on SPI2
Load: dtoverlay=enc28j60-spi2,<param>=<val>
Params: int_pin GPIO used for INT (default 39)
speed SPI bus speed (default 12000000)
Name: exc3000
Info: Enables I2C connected EETI EXC3000 multiple touch controller using
GPIO 4 (pin 7 on GPIO header) for interrupt.
Load: dtoverlay=exc3000,<param>=<val>
Params: interrupt GPIO used for interrupt (default 4)
sizex Touchscreen size x (default 4096)
sizey Touchscreen size y (default 4096)
invx Touchscreen inverted x axis
invy Touchscreen inverted y axis
swapxy Touchscreen swapped x y axis
Name: fe-pi-audio
Info: Configures the Fe-Pi Audio Sound Card
Load: dtoverlay=fe-pi-audio
Params: <None>
Name: fsm-demo
Info: A demonstration of the gpio-fsm driver. The GPIOs are chosen to work
nicely with a "traffic-light" display of red, amber and green LEDs on
GPIOs 7, 8 and 25 respectively.
Load: dtoverlay=fsm-demo,<param>=<val>
Params: fsm_debug Enable debug logging (default off)
Name: ghost-amp
Info: An overlay for the Ghost amplifier.
Load: dtoverlay=ghost-amp,<param>=<val>
Params: fsm_debug Enable debug logging of the GPIO FSM (default off)
Name: goodix
Info: Enables I2C connected Goodix gt9271 multiple touch controller using
GPIOs 4 and 17 (pins 7 and 11 on GPIO header) for interrupt and reset.
Load: dtoverlay=goodix,<param>=<val>
Params: interrupt GPIO used for interrupt (default 4)
reset GPIO used for reset (default 17)
Name: googlevoicehat-soundcard
Info: Configures the Google voiceHAT soundcard
Load: dtoverlay=googlevoicehat-soundcard
Params: <None>
Name: gpio-fan
Info: Configure a GPIO pin to control a cooling fan.
Load: dtoverlay=gpio-fan,<param>=<val>
Params: gpiopin GPIO used to control the fan (default 12)
temp Temperature at which the fan switches on, in millicelcius (default 55000)
Name: gpio-ir
Info: Use GPIO pin as rc-core style infrared receiver input. The rc-core- based gpio_ir_recv driver maps received keys directly to a /dev/input/event* device, all decoding is done by the kernel - LIRC is not required! The key mapping and other decoding parameters can be configured by "ir-keytable" tool.
# 使用GPIO引脚作为rc核心样式的红外接收器输入。基于rc-core的gpio_ir_recv驱动程序将接收到的密钥直接映射到/dev/input/event*设备，所有解码均由内核完成-不需要LIRC！密钥映射和其他解码参数可以通过“ir-keytable”工具进行配置。
Load: dtoverlay=gpio-ir,<param>=<val>
Params: gpio_pin Input pin number. Default is 18. # 输入引脚号。默认值为18。
gpio_pull Desired pull-up/down state (off, down, up) Default is "up". # 所需的上拉/下拉状态（off,down,up）默认为“up”。
invert "1" = invert the input (active-low signalling). # 取反输入（低电平有效信号）。
"0" = non-inverted input (active-high signalling). # 同相输入（高电平有效信号）。
Default is "1". # 默认值为“ 1”。
rc-map-name Default rc keymap (can also be changed by ir-keytable), defaults to "rc-rc6-mce" # 默认的rc键映射(也可以通过ir-keytable更改)，默认为“ rc-rc6-mce”Name: gpio-ir-tx
Info: Use GPIO pin as bit-banged infrared transmitter output.
# 使用GPIO引脚作为位撞击式红外发射器输出。
This is an alternative to "pwm-ir-tx". gpio-ir-tx doesn't require a PWM so it can be used together with onboard analog audio.
# 这是“pwm-ir-tx”的替代方法.gpio-ir-tx不需要PWM,因此可以与板载模拟音频一起使用。
Load: dtoverlay=gpio-ir-tx,<param>=<val>
Params: gpio_pin Output GPIO (default 18) # 输出GPIO(默认18)
invert "1" = invert the output (make it active-low).Default is "0" (active-high).
# 取反输出（使其为低电平有效）。默认值为“ 0”（有效为高电平）。Name: gpio-key
Info: This is a generic overlay for activating GPIO keypresses using
the gpio-keys library and this dtoverlay. Multiple keys can be
set up using multiple calls to the overlay for configuring
additional buttons or joysticks. You can see available keycodes
at https://github.com/torvalds/linux/blob/v4.12/include/uapi/
linux/input-event-codes.h#L64
Load: dtoverlay=gpio-key,<param>=<val>
Params: gpio GPIO pin to trigger on (default 3)
active_low When this is 1 (active low), a falling
edge generates a key down event and a
rising edge generates a key up event.
When this is 0 (active high), this is
reversed. The default is 1 (active low)
gpio_pull Desired pull-up/down state (off, down, up)
Default is "up". Note that the default pin
(GPIO3) has an external pullup
label Set a label for the key
keycode Set the key code for the button
Name: gpio-no-bank0-irq
Info: Use this overlay to disable GPIO interrupts for GPIOs in bank 0 (0-27),
which can be useful for UIO drivers.
N.B. Using this overlay will trigger a kernel WARN during booting, but
this can safely be ignored - the system should work as expected.
Load: dtoverlay=gpio-no-bank0-irq
Params: <None>
Name: gpio-no-irq
Info: Use this overlay to disable all GPIO interrupts, which can be useful
for user-space GPIO edge detection systems.
Load: dtoverlay=gpio-no-irq
Params: <None>
Name: gpio-poweroff
Info: Drives a GPIO high or low on poweroff (including halt). Enabling this
overlay will prevent the ability to boot by driving GPIO3 low.
Load: dtoverlay=gpio-poweroff,<param>=<val>
Params: gpiopin GPIO for signalling (default 26)
active_low Set if the power control device requires a
high->low transition to trigger a power-down.
Note that this will require the support of a
custom dt-blob.bin to prevent a power-down
during the boot process, and that a reboot
will also cause the pin to go low.
input Set if the gpio pin should be configured as
an input.
export Set to export the configured pin to sysfs
timeout_ms Specify (in ms) how long the kernel waits for
power-down before issuing a WARN (default 3000).
Name: gpio-shutdown
Info: Initiates a shutdown when GPIO pin changes. The given GPIO pin
is configured as an input key that generates KEY_POWER events.
This event is handled by systemd-logind by initiating a
shutdown. Systemd versions older than 225 need an udev rule
enable listening to the input device:
ACTION!="REMOVE", SUBSYSTEM=="input", KERNEL=="event*", \
SUBSYSTEMS=="platform", DRIVERS=="gpio-keys", \
ATTRS{keys}=="116", TAG+="power-switch"
Alternatively this event can be handled also on systems without
systemd, just by traditional SysV init daemon. KEY_POWER event
(keycode 116) needs to be mapped to KeyboardSignal on console
and then kb::kbrequest inittab action which is triggered by
KeyboardSignal from console can be configured to issue system
shutdown. Steps for this configuration are:
Add following lines to the /etc/console-setup/remap.inc file:
# Key Power as special keypress
keycode 116 = KeyboardSignal
Then add following lines to /etc/inittab file:
# Action on special keypress (Key Power)
kb::kbrequest:/sbin/shutdown -t1 -a -h -P now
And finally reload configuration by calling following commands:
# dpkg-reconfigure console-setup
# service console-setup reload
# init q
This overlay only handles shutdown. After shutdown, the system
can be powered up again by driving GPIO3 low. The default
configuration uses GPIO3 with a pullup, so if you connect a
button between GPIO3 and GND (pin 5 and 6 on the 40-pin header),
you get a shutdown and power-up button. Please note that
Raspberry Pi 1 Model B rev 1 uses GPIO1 instead of GPIO3.
Load: dtoverlay=gpio-shutdown,<param>=<val>
Params: gpio_pin GPIO pin to trigger on (default 3)
For Raspberry Pi 1 Model B rev 1 set this
explicitly to value 1, e.g.:
dtoverlay=gpio-shutdown,gpio_pin=1
active_low When this is 1 (active low), a falling
edge generates a key down event and a
rising edge generates a key up event.
When this is 0 (active high), this is
reversed. The default is 1 (active low).
gpio_pull Desired pull-up/down state (off, down, up)
Default is "up".
Note that the default pin (GPIO3) has an
external pullup. Same applies for GPIO1
on Raspberry Pi 1 Model B rev 1.
debounce Specify the debounce interval in milliseconds
(default 100)
Name: hd44780-lcd
Info: Configures an HD44780 compatible LCD display. Uses 4 gpio pins for
data, 2 gpio pins for enable and register select and 1 optional pin
for enabling/disabling the backlight display.
Load: dtoverlay=hd44780-lcd,<param>=<val>
Params: pin_d4 GPIO pin for data pin D4 (default 6)
pin_d5 GPIO pin for data pin D5 (default 13)
pin_d6 GPIO pin for data pin D6 (default 19)
pin_d7 GPIO pin for data pin D7 (default 26)
pin_en GPIO pin for "Enable" (default 21)
pin_rs GPIO pin for "Register Select" (default 20)
pin_bl Optional pin for enabling/disabling the
display backlight. (default disabled)
display_height Height of the display in characters
display_width Width of the display in characters
Name: hdmi-backlight-hwhack-gpio
Info: Devicetree overlay for GPIO based backlight on/off capability.
Use this if you have one of those HDMI displays whose backlight cannot
be controlled via DPMS over HDMI and plan to do a little soldering to
use an RPi gpio pin for on/off switching. See:
https://www.waveshare.com/wiki/7inch_HDMI_LCD_(C)#Backlight_Control
Load: dtoverlay=hdmi-backlight-hwhack-gpio,<param>=<val>
Params: gpio_pin GPIO pin used (default 17)
active_low Set this to 1 if the display backlight is
switched on when the wire goes low.
Leave the default (value 0) if the backlight
expects a high to switch it on.
Name: hifiberry-amp
Info: Configures the HifiBerry Amp and Amp+ audio cards
Load: dtoverlay=hifiberry-amp
Params: <None>
Name: hifiberry-dac
Info: Configures the HifiBerry DAC audio card
Load: dtoverlay=hifiberry-dac
Params: <None>
Name: hifiberry-dacplus
Info: Configures the HifiBerry DAC+ audio card
Load: dtoverlay=hifiberry-dacplus,<param>=<val>
Params: 24db_digital_gain Allow gain to be applied via the PCM512x codec
Digital volume control. Enable with
"dtoverlay=hifiberry-dacplus,24db_digital_gain"
(The default behaviour is that the Digital
volume control is limited to a maximum of
0dB. ie. it can attenuate but not provide
gain. For most users, this will be desired
as it will prevent clipping. By appending
the 24dB_digital_gain parameter, the Digital
volume control will allow up to 24dB of
gain. If this parameter is enabled, it is the
responsibility of the user to ensure that
the Digital volume control is set to a value
that does not result in clipping/distortion!)
slave Force DAC+ Pro into slave mode, using Pi as
master for bit clock and frame clock.
leds_off If set to 'true' the onboard indicator LEDs
are switched off at all times.
Name: hifiberry-dacplusadc
Info: Configures the HifiBerry DAC+ADC audio card
Load: dtoverlay=hifiberry-dacplusadc,<param>=<val>
Params: 24db_digital_gain Allow gain to be applied via the PCM512x codec
Digital volume control. Enable with
"dtoverlay=hifiberry-dacplus,24db_digital_gain"
(The default behaviour is that the Digital
volume control is limited to a maximum of
0dB. ie. it can attenuate but not provide
gain. For most users, this will be desired
as it will prevent clipping. By appending
the 24dB_digital_gain parameter, the Digital
volume control will allow up to 24dB of
gain. If this parameter is enabled, it is the
responsibility of the user to ensure that
the Digital volume control is set to a value
that does not result in clipping/distortion!)
slave Force DAC+ Pro into slave mode, using Pi as
master for bit clock and frame clock.
leds_off If set to 'true' the onboard indicator LEDs
are switched off at all times.
Name: hifiberry-dacplusadcpro
Info: Configures the HifiBerry DAC+ADC PRO audio card
Load: dtoverlay=hifiberry-dacplusadcpro,<param>=<val>
Params: 24db_digital_gain Allow gain to be applied via the PCM512x codec
Digital volume control. Enable with
"dtoverlay=hifiberry-dacplusadcpro,24db_digital_gain"
(The default behaviour is that the Digital
volume control is limited to a maximum of
0dB. ie. it can attenuate but not provide
gain. For most users, this will be desired
as it will prevent clipping. By appending
the 24dB_digital_gain parameter, the Digital
volume control will allow up to 24dB of
gain. If this parameter is enabled, it is the
responsibility of the user to ensure that
the Digital volume control is set to a value
that does not result in clipping/distortion!)
slave Force DAC+ADC Pro into slave mode, using Pi as
master for bit clock and frame clock.
leds_off If set to 'true' the onboard indicator LEDs
are switched off at all times.
Name: hifiberry-dacplusdsp
Info: Configures the HifiBerry DAC+DSP audio card
Load: dtoverlay=hifiberry-dacplusdsp
Params: <None>
Name: hifiberry-dacplushd
Info: Configures the HifiBerry DAC+ HD audio card
Load: dtoverlay=hifiberry-dacplushd
Params: <None>
Name: hifiberry-digi
Info: Configures the HifiBerry Digi and Digi+ audio card
Load: dtoverlay=hifiberry-digi
Params: <None>
Name: hifiberry-digi-pro
Info: Configures the HifiBerry Digi+ Pro audio card
Load: dtoverlay=hifiberry-digi-pro
Params: <None>
Name: highperi
Info: Enables "High Peripheral" mode
Load: dtoverlay=highperi
Params: <None>
Name: hy28a
Info: HY28A - 2.8" TFT LCD Display Module by HAOYU Electronics
Default values match Texy's display shield
Load: dtoverlay=hy28a,<param>=<val>
Params: speed Display SPI bus speed
rotate Display rotation {0,90,180,270}
fps Delay between frame updates
debug Debug output level {0-7}
xohms Touchpanel sensitivity (X-plate resistance)
resetgpio GPIO used to reset controller
ledgpio GPIO used to control backlight
Name: hy28b
Info: HY28B - 2.8" TFT LCD Display Module by HAOYU Electronics
Default values match Texy's display shield
Load: dtoverlay=hy28b,<param>=<val>
Params: speed Display SPI bus speed
rotate Display rotation {0,90,180,270}
fps Delay between frame updates
debug Debug output level {0-7}
xohms Touchpanel sensitivity (X-plate resistance)
resetgpio GPIO used to reset controller
ledgpio GPIO used to control backlight
Name: hy28b-2017
Info: HY28B 2017 version - 2.8" TFT LCD Display Module by HAOYU Electronics
Default values match Texy's display shield
Load: dtoverlay=hy28b-2017,<param>=<val>
Params: speed Display SPI bus speed
rotate Display rotation {0,90,180,270}
fps Delay between frame updates
debug Debug output level {0-7}
xohms Touchpanel sensitivity (X-plate resistance)
resetgpio GPIO used to reset controller
ledgpio GPIO used to control backlight
Name: i-sabre-q2m
Info: Configures the Audiophonics I-SABRE Q2M DAC
Load: dtoverlay=i-sabre-q2m
Params: <None>
Name: i2c-bcm2708
Info: Fall back to the i2c_bcm2708 driver for the i2c_arm bus.
Load: dtoverlay=i2c-bcm2708
Params: <None>
Name: i2c-gpio
Info: Adds support for software i2c controller on gpio pins
Load: dtoverlay=i2c-gpio,<param>=<val>
Params: i2c_gpio_sda GPIO used for I2C data (default "23")
i2c_gpio_scl GPIO used for I2C clock (default "24")
i2c_gpio_delay_us Clock delay in microseconds
(default "2" = ~100kHz)
bus Set to a unique, non-zero value if wanting
multiple i2c-gpio busses. If set, will be used
as the preferred bus number (/dev/i2c-<n>). If
not set, the default value is 0, but the bus
number will be dynamically assigned - probably
3.
Name: i2c-mux
Info: Adds support for a number of I2C bus multiplexers on i2c_arm
Load: dtoverlay=i2c-mux,<param>=<val>
Params: pca9542 Select the NXP PCA9542 device
pca9545 Select the NXP PCA9545 device
pca9548 Select the NXP PCA9548 device
addr Change I2C address of the device (default 0x70)
[ The i2c-mux-pca9548a overlay has been deleted. See i2c-mux. ]
Name: i2c-pwm-pca9685a
Info: Adds support for an NXP PCA9685A I2C PWM controller on i2c_arm
Load: dtoverlay=i2c-pwm-pca9685a,<param>=<val>
Params: addr I2C address of PCA9685A (default 0x40)
Name: i2c-rtc
Info: Adds support for a number of I2C Real Time Clock devices
Load: dtoverlay=i2c-rtc,<param>=<val>
Params: abx80x Select one of the ABx80x family:
AB0801, AB0803, AB0804, AB0805,
AB1801, AB1803, AB1804, AB1805
ds1307 Select the DS1307 device
ds1339 Select the DS1339 device
ds3231 Select the DS3231 device
m41t62 Select the M41T62 device
mcp7940x Select the MCP7940x device
mcp7941x Select the MCP7941x device
pcf2127 Select the PCF2127 device
pcf2129 Select the PCF2129 device
pcf85063 Select the PCF85063 device
pcf85063a Select the PCF85063A device
pcf8523 Select the PCF8523 device
pcf85363 Select the PCF85363 device
pcf8563 Select the PCF8563 device
rv1805 Select the Micro Crystal RV1805 device
rv3028 Select the Micro Crystal RV3028 device
sd3078 Select the ZXW Shenzhen whwave SD3078 device
i2c0 Choose the I2C0 bus on GPIOs 0&1
i2c_csi_dsi Choose the I2C0 bus on GPIOs 44&45
addr Sets the address for the RTC. Note that the
device must be configured to use the specified
address.
trickle-diode-type Diode type for trickle charge - "standard" or
"schottky" (ABx80x and RV1805 only)
trickle-resistor-ohms Resistor value for trickle charge (DS1339,
ABx80x, RV1805, RV3028)
wakeup-source Specify that the RTC can be used as a wakeup
source
backup-switchover-mode Backup power supply switch mode. Must be 0 for
off or 1 for Vdd < VBackup (RV3028 only)
Name: i2c-rtc-gpio
Info: Adds support for a number of I2C Real Time Clock devices
using the software i2c controller
Load: dtoverlay=i2c-rtc-gpio,<param>=<val>
Params: abx80x Select one of the ABx80x family:
AB0801, AB0803, AB0804, AB0805,
AB1801, AB1803, AB1804, AB1805
ds1307 Select the DS1307 device
ds1339 Select the DS1339 device
ds3231 Select the DS3231 device
m41t62 Select the M41T62 device
mcp7940x Select the MCP7940x device
mcp7941x Select the MCP7941x device
pcf2127 Select the PCF2127 device
pcf2129 Select the PCF2129 device
pcf8523 Select the PCF8523 device
pcf8563 Select the PCF8563 device
rv1805 Select the Micro Crystal RV1805 device
rv3028 Select the Micro Crystal RV3028 device
addr Sets the address for the RTC. Note that the
device must be configured to use the specified
address.
trickle-diode-type Diode type for trickle charge - "standard" or
"schottky" (ABx80x and RV1805 only)
trickle-resistor-ohms Resistor value for trickle charge (DS1339,
ABx80x, RV1805, RV3028)
wakeup-source Specify that the RTC can be used as a wakeup
source
backup-switchover-mode Backup power supply switch mode. Must be 0 for
off or 1 for Vdd < VBackup (RV3028 only)
i2c_gpio_sda GPIO used for I2C data (default "23")
i2c_gpio_scl GPIO used for I2C clock (default "24")
i2c_gpio_delay_us Clock delay in microseconds
(default "2" = ~100kHz)
Name: i2c-sensor
Info: Adds support for a number of I2C barometric pressure and temperature
sensors on i2c_arm
Load: dtoverlay=i2c-sensor,<param>=<val>
Params: addr Set the address for the BME280, BME680, BMP280,
DS1621, HDC100X, LM75, SHT3x or TMP102
bme280 Select the Bosch Sensortronic BME280
Valid addresses 0x76-0x77, default 0x76
bme680 Select the Bosch Sensortronic BME680
Valid addresses 0x76-0x77, default 0x76
bmp085 Select the Bosch Sensortronic BMP085
bmp180 Select the Bosch Sensortronic BMP180
bmp280 Select the Bosch Sensortronic BMP280
Valid addresses 0x76-0x77, default 0x76
ds1621 Select the Dallas Semiconductors DS1621 temp
sensor. Valid addresses 0x48-0x4f, default 0x48
hdc100x Select the Texas Instruments HDC100x temp sensor
Valid addresses 0x40-0x43, default 0x40
htu21 Select the HTU21 temperature and humidity sensor
lm75 Select the Maxim LM75 temperature sensor
Valid addresses 0x48-0x4f, default 0x4f
lm75addr Deprecated - use addr parameter instead
max17040 Select the Maxim Integrated MAX17040 battery
monitor
sht3x Select the Sensiron SHT3x temperature and
humidity sensor. Valid addresses 0x44-0x45,
default 0x44
si7020 Select the Silicon Labs Si7013/20/21 humidity/
temperature sensor
sps30 Select the Sensirion SPS30 particulate matter
sensor. Fixed address 0x69.
tmp102 Select the Texas Instruments TMP102 temp sensor
Valid addresses 0x48-0x4b, default 0x48
tsl4531 Select the AMS TSL4531 digital ambient light
sensor
veml6070 Select the Vishay VEML6070 ultraviolet light
sensor
Name: i2c0
Info: Change i2c0 pin usage. Not all pin combinations are usable on all
platforms - platforms other then Compute Modules can only use this
to disable transaction combining.
Do NOT use in conjunction with dtparam=i2c_vc=on. From the 5.4 kernel
onwards the base DT includes the use of i2c_mux_pinctrl to expose two
muxings of BSC0 - GPIOs 0&1, and whichever combination is used for the
camera and display connectors. This overlay disables that mux and
configures /dev/i2c0 to point at whichever set of pins is requested.
dtparam=i2c_vc=on will try and enable the mux, so combining the two
will cause conflicts.
Load: dtoverlay=i2c0,<param>=<val>
Params: pins_0_1 Use pins 0 and 1 (default)
pins_28_29 Use pins 28 and 29
pins_44_45 Use pins 44 and 45
pins_46_47 Use pins 46 and 47
combine Allow transactions to be combined (default
"yes")
Name: i2c0-bcm2708
Info: Deprecated, legacy version of i2c0.
Load: <Deprecated>
Name: i2c1
Info: Change i2c1 pin usage. Not all pin combinations are usable on all
platforms - platforms other then Compute Modules can only use this
to disable transaction combining.
Load: dtoverlay=i2c1,<param>=<val>
Params: pins_2_3 Use pins 2 and 3 (default)
pins_44_45 Use pins 44 and 45
combine Allow transactions to be combined (default
"yes")
Name: i2c1-bcm2708
Info: Deprecated, legacy version of i2c1.
Load: <Deprecated>
Name: i2c3
Info: Enable the i2c3 bus. BCM2711 only.
Load: dtoverlay=i2c3,<param>
Params: pins_2_3 Use GPIOs 2 and 3
pins_4_5 Use GPIOs 4 and 5 (default)
baudrate Set the baudrate for the interface (default
"100000")
Name: i2c4
Info: Enable the i2c4 bus. BCM2711 only.
Load: dtoverlay=i2c4,<param>
Params: pins_6_7 Use GPIOs 6 and 7
pins_8_9 Use GPIOs 8 and 9 (default)
baudrate Set the baudrate for the interface (default
"100000")
Name: i2c5
Info: Enable the i2c5 bus. BCM2711 only.
Load: dtoverlay=i2c5,<param>
Params: pins_10_11 Use GPIOs 10 and 11
pins_12_13 Use GPIOs 12 and 13 (default)
baudrate Set the baudrate for the interface (default
"100000")
Name: i2c6
Info: Enable the i2c6 bus. BCM2711 only.
Load: dtoverlay=i2c6,<param>
Params: pins_0_1 Use GPIOs 0 and 1
pins_22_23 Use GPIOs 22 and 23 (default)
baudrate Set the baudrate for the interface (default
"100000")
Name: i2s-gpio28-31
Info: move I2S function block to GPIO 28 to 31
Load: dtoverlay=i2s-gpio28-31
Params: <None>
Name: ilitek251x
Info: Enables I2C connected Ilitek 251x multiple touch controller using
GPIO 4 (pin 7 on GPIO header) for interrupt.
Load: dtoverlay=ilitek251x,<param>=<val>
Params: interrupt GPIO used for interrupt (default 4)
sizex Touchscreen size x, horizontal resolution of
touchscreen (in pixels)
sizey Touchscreen size y, vertical resolution of
touchscreen (in pixels)
Name: imx219
Info: Sony IMX219 camera module.
Uses Unicam 1, which is the standard camera connector on most Pi
variants.
Load: dtoverlay=imx219,<param>=<val>
Params: rotation Mounting rotation of the camera sensor (0 or
180, default 180)
Name: imx290
Info: Sony IMX290 camera module.
Uses Unicam 1, which is the standard camera connector on most Pi
variants. NB This currently uses 4 CSI2 data lanes and therefore will
only work on a CM.
Load: dtoverlay=imx290,<param>
Params: 4lane Enable 4 CSI2 lanes. This requires a Compute
Module (1, 3, or 4).
clock-frequency Sets the clock frequency to match that used on
the board.
Modules from Vision Components use 37.125MHz
(the default), whilst those from Innomaker use
74.25MHz.
mono Denote that the module is a mono sensor.
Name: imx477
Info: Sony IMX477 camera module.
Uses Unicam 1, which is the standard camera connector on most Pi
variants.
Load: dtoverlay=imx477,<param>=<val>
Params: rotation Mounting rotation of the camera sensor (0 or
180, default 180)
Name: iqaudio-codec
Info: Configures the IQaudio Codec audio card
Load: dtoverlay=iqaudio-codec
Params: <None>
Name: iqaudio-dac
Info: Configures the IQaudio DAC audio card
Load: dtoverlay=iqaudio-dac,<param>
Params: 24db_digital_gain Allow gain to be applied via the PCM512x codec
Digital volume control. Enable with
"dtoverlay=iqaudio-dac,24db_digital_gain"
(The default behaviour is that the Digital
volume control is limited to a maximum of
0dB. ie. it can attenuate but not provide
gain. For most users, this will be desired
as it will prevent clipping. By appending
the 24db_digital_gain parameter, the Digital
volume control will allow up to 24dB of
gain. If this parameter is enabled, it is the
responsibility of the user to ensure that
the Digital volume control is set to a value
that does not result in clipping/distortion!)
Name: iqaudio-dacplus
Info: Configures the IQaudio DAC+ audio card
Load: dtoverlay=iqaudio-dacplus,<param>=<val>
Params: 24db_digital_gain Allow gain to be applied via the PCM512x codec
Digital volume control. Enable with
"dtoverlay=iqaudio-dacplus,24db_digital_gain"
(The default behaviour is that the Digital
volume control is limited to a maximum of
0dB. ie. it can attenuate but not provide
gain. For most users, this will be desired
as it will prevent clipping. By appending
the 24db_digital_gain parameter, the Digital
volume control will allow up to 24dB of
gain. If this parameter is enabled, it is the
responsibility of the user to ensure that
the Digital volume control is set to a value
that does not result in clipping/distortion!)
auto_mute_amp If specified, unmute/mute the IQaudIO amp when
starting/stopping audio playback.
unmute_amp If specified, unmute the IQaudIO amp once when
the DAC driver module loads.
Name: iqaudio-digi-wm8804-audio
Info: Configures the IQAudIO Digi WM8804 audio card
Load: dtoverlay=iqaudio-digi-wm8804-audio,<param>=<val>
Params: card_name Override the default, "IQAudIODigi", card name.
dai_name Override the default, "IQAudIO Digi", dai name.
dai_stream_name Override the default, "IQAudIO Digi HiFi",
dai stream name.
Name: irs1125
Info: Infineon irs1125 TOF camera module.
Uses Unicam 1, which is the standard camera connector on most Pi
variants.
Load: dtoverlay=irs1125
Params: <None>
Name: jedec-spi-nor
Info: Adds support for JEDEC-compliant SPI NOR flash devices. (Note: The
"jedec,spi-nor" kernel driver was formerly known as "m25p80".)
Load: dtoverlay=jedec-spi-nor,<param>=<val>
Params: flash-spi<n>-<m> Enables flash device on SPI<n>, CS#<m>.
flash-fastr-spi<n>-<m> Enables flash device with fast read capability
on SPI<n>, CS#<m>.
Name: justboom-both
Info: Simultaneous usage of an justboom-dac and justboom-digi based
card
Load: dtoverlay=justboom-both,<param>=<val>
Params: 24db_digital_gain Allow gain to be applied via the PCM512x codec
Digital volume control. Enable with
"dtoverlay=justboom-dac,24db_digital_gain"
(The default behaviour is that the Digital
volume control is limited to a maximum of
0dB. ie. it can attenuate but not provide
gain. For most users, this will be desired
as it will prevent clipping. By appending
the 24dB_digital_gain parameter, the Digital
volume control will allow up to 24dB of
gain. If this parameter is enabled, it is the
responsibility of the user to ensure that
the Digital volume control is set to a value
that does not result in clipping/distortion!)
Name: justboom-dac
Info: Configures the JustBoom DAC HAT, Amp HAT, DAC Zero and Amp Zero audio
cards
Load: dtoverlay=justboom-dac,<param>=<val>
Params: 24db_digital_gain Allow gain to be applied via the PCM512x codec
Digital volume control. Enable with
"dtoverlay=justboom-dac,24db_digital_gain"
(The default behaviour is that the Digital
volume control is limited to a maximum of
0dB. ie. it can attenuate but not provide
gain. For most users, this will be desired
as it will prevent clipping. By appending
the 24dB_digital_gain parameter, the Digital
volume control will allow up to 24dB of
gain. If this parameter is enabled, it is the
responsibility of the user to ensure that
the Digital volume control is set to a value
that does not result in clipping/distortion!)
Name: justboom-digi
Info: Configures the JustBoom Digi HAT and Digi Zero audio cards
Load: dtoverlay=justboom-digi
Params: <None>
Name: lirc-rpi
Info: This overlay has been deprecated and removed - see gpio-ir # 已弃用并删除-参见gpio-ir
Load: <Deprecated>
Name: ltc294x
Info: Adds support for the ltc294x family of battery gauges
Load: dtoverlay=ltc294x,<param>=<val>
Params: ltc2941 Select the ltc2941 device
ltc2942 Select the ltc2942 device
ltc2943 Select the ltc2943 device
ltc2944 Select the ltc2944 device
resistor-sense The sense resistor value in milli-ohms.
Can be a 32-bit negative value when the battery
has been connected to the wrong end of the
resistor.
prescaler-exponent Range and accuracy of the gauge. The value is
programmed into the chip only if it differs
from the current setting.
For LTC2941 only:
- Default value is 128
- the exponent is in the range 0-7 (default 7)
See the datasheet for more information.
Name: max98357a
Info: Configures the Maxim MAX98357A I2S DAC
Load: dtoverlay=max98357a,<param>=<val>
Params: no-sdmode Driver does not manage the state of the DAC's
SD_MODE pin (i.e. chip is always on).
sdmode-pin integer, GPIO pin connected to the SD_MODE input
of the DAC (default GPIO4 if parameter omitted).
Name: maxtherm
Info: Configure a MAX6675, MAX31855 or MAX31856 thermocouple as an IIO device.
For devices on spi1 or spi2, the interfaces should be enabled
with one of the spi1-1/2/3cs and/or spi2-1/2/3cs overlays.
The overlay expects to disable the relevant spidev node, so also using
e.g. cs0_spidev=off is unnecessary.
Example:
MAX31855 on /dev/spidev0.0
dtoverlay=maxtherm,spi0-0,max31855
MAX31856 using a type J thermocouple on /dev/spidev2.1
dtoverlay=spi2-2cs
dtoverlay=maxtherm,spi2-1,max31856,type_j
Load: dtoverlay=maxtherm,<param>=<val>
Params: spi<n>-<m> Configure device at spi<n>, cs<m>
(boolean, required)
max6675 Enable support for the MAX6675 (default)
max31855 Enable support for the MAX31855
max31855e Enable support for the MAX31855E
max31855j Enable support for the MAX31855J
max31855k Enable support for the MAX31855K
max31855n Enable support for the MAX31855N
max31855r Enable support for the MAX31855R
max31855s Enable support for the MAX31855S
max31855t Enable support for the MAX31855T
max31856 Enable support for the MAX31856 (with type K)
type_b Select a type B sensor for max31856
type_e Select a type E sensor for max31856
type_j Select a type J sensor for max31856
type_k Select a type K sensor for max31856
type_n Select a type N sensor for max31856
type_r Select a type R sensor for max31856
type_s Select a type S sensor for max31856
type_t Select a type T sensor for max31856
Name: mbed-dac
Info: Configures the mbed AudioCODEC (TLV320AIC23B)
Load: dtoverlay=mbed-dac
Params: <None>
Name: mcp23017
Info: Configures the MCP23017 I2C GPIO expander
Load: dtoverlay=mcp23017,<param>=<val>
Params: gpiopin Gpio pin connected to the INTA output of the
MCP23017 (default: 4)
addr I2C address of the MCP23017 (default: 0x20)
mcp23008 Configure an MCP23008 instead.
noints Disable the interrupt GPIO line.
Name: mcp23s17
Info: Configures the MCP23S08/17 SPI GPIO expanders.
If devices are present on SPI1 or SPI2, those interfaces must be enabled
with one of the spi1-1/2/3cs and/or spi2-1/2/3cs overlays.
If interrupts are enabled for a device on a given CS# on a SPI bus, that
device must be the only one present on that SPI bus/CS#.
Load: dtoverlay=mcp23s17,<param>=<val>
Params: s08-spi<n>-<m>-present 4-bit integer, bitmap indicating MCP23S08
devices present on SPI<n>, CS#<m>
s17-spi<n>-<m>-present 8-bit integer, bitmap indicating MCP23S17
devices present on SPI<n>, CS#<m>
s08-spi<n>-<m>-int-gpio integer, enables interrupts on a single
MCP23S08 device on SPI<n>, CS#<m>, specifies
the GPIO pin to which INT output of MCP23S08
is connected.
s17-spi<n>-<m>-int-gpio integer, enables mirrored interrupts on a
single MCP23S17 device on SPI<n>, CS#<m>,
specifies the GPIO pin to which either INTA
or INTB output of MCP23S17 is connected.
Name: mcp2515-can0
Info: Configures the MCP2515 CAN controller on spi0.0
Load: dtoverlay=mcp2515-can0,<param>=<val>
Params: oscillator Clock frequency for the CAN controller (Hz)
spimaxfrequency Maximum SPI frequence (Hz)
interrupt GPIO for interrupt signal
Name: mcp2515-can1
Info: Configures the MCP2515 CAN controller on spi0.1
Load: dtoverlay=mcp2515-can1,<param>=<val>
Params: oscillator Clock frequency for the CAN controller (Hz)
spimaxfrequency Maximum SPI frequence (Hz)
interrupt GPIO for interrupt signal
Name: mcp251xfd
Info: Configures the MCP251XFD CAN controller family
For devices on spi1 or spi2, the interfaces should be enabled
with one of the spi1-1/2/3cs and/or spi2-1/2/3cs overlays.
Load: dtoverlay=mcp251xfd,<param>=<val>
Params: spi<n>-<m> Configure device at spi<n>, cs<m>
(boolean, required)
oscillator Clock frequency for the CAN controller (Hz)
speed Maximum SPI frequence (Hz)
interrupt GPIO for interrupt signal
rx_interrupt GPIO for RX interrupt signal (nINT1) (optional)
xceiver_enable GPIO for CAN transceiver enable (optional)
xceiver_active_high specifiy if CAN transceiver enable pin is
active high (optional, default: active low)
Name: mcp3008
Info: Configures MCP3008 A/D converters
For devices on spi1 or spi2, the interfaces should be enabled
with one of the spi1-1/2/3cs and/or spi2-1/2/3cs overlays.
Load: dtoverlay=mcp3008,<param>[=<val>]
Params: spi<n>-<m>-present boolean, configure device at spi<n>, cs<m>
spi<n>-<m>-speed integer, set the spi bus speed for this device
Name: mcp3202
Info: Configures MCP3202 A/D converters
For devices on spi1 or spi2, the interfaces should be enabled
with one of the spi1-1/2/3cs and/or spi2-1/2/3cs overlays.
Load: dtoverlay=mcp3202,<param>[=<val>]
Params: spi<n>-<m>-present boolean, configure device at spi<n>, cs<m>
spi<n>-<m>-speed integer, set the spi bus speed for this device
Name: mcp342x
Info: Overlay for activation of Microchip MCP3421-3428 ADCs over I2C
Load: dtoverlay=mcp342x,<param>=<val>
Params: addr I2C bus address of device, for devices with
addresses that are configurable, e.g. by
hardware links (default=0x68)
mcp3421 The device is an MCP3421
mcp3422 The device is an MCP3422
mcp3423 The device is an MCP3423
mcp3424 The device is an MCP3424
mcp3425 The device is an MCP3425
mcp3426 The device is an MCP3426
mcp3427 The device is an MCP3427
mcp3428 The device is an MCP3428
Name: media-center
Info: Media Center HAT - 2.83" Touch Display + extras by Pi Supply
Load: dtoverlay=media-center,<param>=<val>
Params: speed Display SPI bus speed
rotate Display rotation {0,90,180,270}
fps Delay between frame updates
xohms Touchpanel sensitivity (X-plate resistance)
swapxy Swap x and y axis
backlight Change backlight GPIO pin {e.g. 12, 18}
gpio_out_pin GPIO for output (default "17")
gpio_in_pin GPIO for input (default "18")
gpio_in_pull Pull up/down/off on the input pin
(default "down")
sense Override the IR receive auto-detection logic:
"0" = force active-high
"1" = force active-low
"-1" = use auto-detection
(default "-1")
softcarrier Turn the software carrier "on" or "off"
(default "on")
invert "on" = invert the output pin (default "off")
debug "on" = enable additional debug messages
(default "off")
Name: merus-amp
Info: Configures the merus-amp audio card
Load: dtoverlay=merus-amp,<param>=<val>
Params: spioff Turn SPI bus off
Name: midi-uart0
Info: Configures UART0 (ttyAMA0) so that a requested 38.4kbaud actually gets
31.25kbaud, the frequency required for MIDI
Load: dtoverlay=midi-uart0
Params: <None>
Name: midi-uart1
Info: Configures UART1 (ttyS0) so that a requested 38.4kbaud actually gets
31.25kbaud, the frequency required for MIDI
Load: dtoverlay=midi-uart1
Params: <None>
Name: miniuart-bt
Info: Switch the onboard Bluetooth function on Pi 3B, 3B+, 3A+, 4B and Zero W
to use the mini-UART (ttyS0) and restore UART0/ttyAMA0 over GPIOs 14 &
15. Note that this may reduce the maximum usable baudrate.
N.B. It is also necessary to edit /lib/systemd/system/hciuart.service
and replace ttyAMA0 with ttyS0, unless using Raspbian or another
distribution with udev rules that create /dev/serial0 and /dev/serial1,
in which case use /dev/serial1 instead because it will always be
correct. Furthermore, you must also set core_freq and core_freq_min to
the same value in config.txt or the miniuart will not work.
Load: dtoverlay=miniuart-bt,<param>=<val>
Params: krnbt Set to "on" to enable autoprobing of Bluetooth
driver without need of hciattach/btattach
Name: mmc
Info: Selects the bcm2835-mmc SD/MMC driver, optionally with overclock
Load: dtoverlay=mmc,<param>=<val>
Params: overclock_50 Clock (in MHz) to use when the MMC framework
requests 50MHz
Name: mpu6050
Info: Overlay for i2c connected mpu6050 imu
Load: dtoverlay=mpu6050,<param>=<val>
Params: interrupt GPIO pin for interrupt (default 4)
addr I2C address of the device (default 0x68)
Name: mz61581
Info: MZ61581 display by Tontec
Load: dtoverlay=mz61581,<param>=<val>
Params: speed Display SPI bus speed
rotate Display rotation {0,90,180,270}
fps Delay between frame updates
txbuflen Transmit buffer length (default 32768)
debug Debug output level {0-7}
xohms Touchpanel sensitivity (X-plate resistance)
Name: ov5647
Info: Omnivision OV5647 camera module.
Uses Unicam 1, which is the standard camera connector on most Pi
variants.
Load: dtoverlay=ov5647,<param>=<val>
Params: rotation Mounting rotation of the camera sensor (0 or
180, default 0)
Name: ov7251
Info: Omnivision OV7251 camera module.
Uses Unicam 1, which is the standard camera connector on most Pi
variants.
Load: dtoverlay=ov7251
Params: <None>
Name: ov9281
Info: Omnivision OV9281 camera module.
Uses Unicam 1, which is the standard camera connector on most Pi
variants.
Load: dtoverlay=ov9281
Params: <None>
Name: papirus
Info: PaPiRus ePaper Screen by Pi Supply (both HAT and pHAT)
Load: dtoverlay=papirus,<param>=<val>
Params: panel Display panel (required):
1.44": e1144cs021
2.0": e2200cs021
2.7": e2271cs021
speed Display SPI bus speed
Name: pca953x
Info: TI PCA953x family of I2C GPIO expanders. Default is for NXP PCA9534.
Load: dtoverlay=pca953x,<param>=<val>
Params: addr I2C address of expander. Default 0x20.
pca6416 Select the NXP PCA6416 (16 bit)
pca9505 Select the NXP PCA9505 (40 bit)
pca9535 Select the NXP PCA9535 (16 bit)
pca9536 Select the NXP PCA9536 or TI PCA9536 (4 bit)
pca9537 Select the NXP PCA9537 (4 bit)
pca9538 Select the NXP PCA9538 (8 bit)
pca9539 Select the NXP PCA9539 (16 bit)
pca9554 Select the NXP PCA9554 (8 bit)
pca9555 Select the NXP PCA9555 (16 bit)
pca9556 Select the NXP PCA9556 (8 bit)
pca9557 Select the NXP PCA9557 (8 bit)
pca9574 Select the NXP PCA9574 (8 bit)
pca9575 Select the NXP PCA9575 (16 bit)
pca9698 Select the NXP PCA9698 (40 bit)
pca16416 Select the NXP PCA16416 (16 bit)
pca16524 Select the NXP PCA16524 (24 bit)
pca19555a Select the NXP PCA19555A (16 bit)
max7310 Select the Maxim MAX7310 (8 bit)
max7312 Select the Maxim MAX7312 (16 bit)
max7313 Select the Maxim MAX7313 (16 bit)
max7315 Select the Maxim MAX7315 (8 bit)
pca6107 Select the TI PCA6107 (8 bit)
tca6408 Select the TI TCA6408 (8 bit)
tca6416 Select the TI TCA6416 (16 bit)
tca6424 Select the TI TCA6424 (24 bit)
tca9539 Select the TI TCA9539 (16 bit)
tca9554 Select the TI TCA9554 (8 bit)
cat9554 Select the Onnn CAT9554 (8 bit)
pca9654 Select the Onnn PCA9654 (8 bit)
xra1202 Select the Exar XRA1202 (8 bit)
[ The pcf2127-rtc overlay has been deleted. See i2c-rtc. ]
[ The pcf8523-rtc overlay has been deleted. See i2c-rtc. ]
[ The pcf8563-rtc overlay has been deleted. See i2c-rtc. ]
Name: pi3-act-led
Info: This overlay has been renamed act-led, keeping pi3-act-led as an alias
for backwards compatibility.
Load: <Deprecated>
Name: pi3-disable-bt
Info: This overlay has been renamed disable-bt, keeping pi3-disable-bt as an
alias for backwards compatibility.
Load: <Deprecated>
Name: pi3-disable-wifi
Info: This overlay has been renamed disable-wifi, keeping pi3-disable-wifi as
an alias for backwards compatibility.
Load: <Deprecated>
Name: pi3-miniuart-bt
Info: This overlay has been renamed miniuart-bt, keeping pi3-miniuart-bt as
an alias for backwards compatibility.
Load: <Deprecated>
Name: pibell
Info: Configures the pibell audio card.
Load: dtoverlay=pibell,<param>=<val>
Params: alsaname Set the name as it appears in ALSA (default
"PiBell")
Name: pifacedigital
Info: Configures the PiFace Digital mcp23s17 GPIO port expander.
Load: dtoverlay=pifacedigital,<param>=<val>
Params: spi-present-mask 8-bit integer, bitmap indicating MCP23S17 SPI0
CS0 address. PiFace Digital supports addresses
0-3, which can be configured with JP1 and JP2.
Name: pifi-40
Info: Configures the PiFi 40W stereo amplifier
Load: dtoverlay=pifi-40
Params: <None>
Name: piglow
Info: Configures the PiGlow by pimoroni.com
Load: dtoverlay=piglow
Params: <None>
Name: piscreen
Info: PiScreen display by OzzMaker.com
Load: dtoverlay=piscreen,<param>=<val>
Params: speed Display SPI bus speed
rotate Display rotation {0,90,180,270}
fps Delay between frame updates
debug Debug output level {0-7}
xohms Touchpanel sensitivity (X-plate resistance)
Name: piscreen2r
Info: PiScreen 2 with resistive TP display by OzzMaker.com
Load: dtoverlay=piscreen2r,<param>=<val>
Params: speed Display SPI bus speed
rotate Display rotation {0,90,180,270}
fps Delay between frame updates
debug Debug output level {0-7}
xohms Touchpanel sensitivity (X-plate resistance)
Name: pisound
Info: Configures the Blokas Labs pisound card
Load: dtoverlay=pisound
Params: <None>
Name: pitft22
Info: Adafruit PiTFT 2.2" screen
Load: dtoverlay=pitft22,<param>=<val>
Params: speed Display SPI bus speed
rotate Display rotation {0,90,180,270}
fps Delay between frame updates
debug Debug output level {0-7}
Name: pitft28-capacitive
Info: Adafruit PiTFT 2.8" capacitive touch screen
Load: dtoverlay=pitft28-capacitive,<param>=<val>
Params: speed Display SPI bus speed
rotate Display rotation {0,90,180,270}
fps Delay between frame updates
debug Debug output level {0-7}
touch-sizex Touchscreen size x (default 240)
touch-sizey Touchscreen size y (default 320)
touch-invx Touchscreen inverted x axis
touch-invy Touchscreen inverted y axis
touch-swapxy Touchscreen swapped x y axis
Name: pitft28-resistive
Info: Adafruit PiTFT 2.8" resistive touch screen
Load: dtoverlay=pitft28-resistive,<param>=<val>
Params: speed Display SPI bus speed
rotate Display rotation {0,90,180,270}
fps Delay between frame updates
debug Debug output level {0-7}
Name: pitft35-resistive
Info: Adafruit PiTFT 3.5" resistive touch screen
Load: dtoverlay=pitft35-resistive,<param>=<val>
Params: speed Display SPI bus speed
rotate Display rotation {0,90,180,270}
fps Delay between frame updates
debug Debug output level {0-7}
Name: pps-gpio
Info: Configures the pps-gpio (pulse-per-second time signal via GPIO).
Load: dtoverlay=pps-gpio,<param>=<val>
Params: gpiopin Input GPIO (default "18")
assert_falling_edge When present, assert is indicated by a falling
edge, rather than by a rising edge (default
off)
capture_clear Generate clear events on the trailing edge
(default off)
Name: pwm
Info: Configures a single PWM channel
Legal pin,function combinations for each channel:
PWM0: 12,4(Alt0) 18,2(Alt5) 40,4(Alt0) 52,5(Alt1)
PWM1: 13,4(Alt0) 19,2(Alt5) 41,4(Alt0) 45,4(Alt0) 53,5(Alt1)
N.B.:
1) Pin 18 is the only one available on all platforms, and
it is the one used by the I2S audio interface.
Pins 12 and 13 might be better choices on an A+, B+ or Pi2.
2) The onboard analogue audio output uses both PWM channels.
3) So be careful mixing audio and PWM.
4) Currently the clock must have been enabled and configured
by other means.
Load: dtoverlay=pwm,<param>=<val>
Params: pin Output pin (default 18) - see table
func Pin function (default 2 = Alt5) - see above
clock PWM clock frequency (informational)
Name: pwm-2chan
Info: Configures both PWM channels
Legal pin,function combinations for each channel:
PWM0: 12,4(Alt0) 18,2(Alt5) 40,4(Alt0) 52,5(Alt1)
PWM1: 13,4(Alt0) 19,2(Alt5) 41,4(Alt0) 45,4(Alt0) 53,5(Alt1)
N.B.:
1) Pin 18 is the only one available on all platforms, and
it is the one used by the I2S audio interface.
Pins 12 and 13 might be better choices on an A+, B+ or Pi2.
2) The onboard analogue audio output uses both PWM channels.
3) So be careful mixing audio and PWM.
4) Currently the clock must have been enabled and configured
by other means.
Load: dtoverlay=pwm-2chan,<param>=<val>
Params: pin Output pin (default 18) - see table
pin2 Output pin for other channel (default 19)
func Pin function (default 2 = Alt5) - see above
func2 Function for pin2 (default 2 = Alt5)
clock PWM clock frequency (informational)
Name: pwm-ir-tx
Info: Use GPIO pin as pwm-assisted infrared transmitter output.
This is an alternative to "gpio-ir-tx". pwm-ir-tx makes use
of PWM0 to reduce the CPU load during transmission compared to
gpio-ir-tx which uses bit-banging.
Legal pin,function combinations are:
12,4(Alt0) 18,2(Alt5) 40,4(Alt0) 52,5(Alt1)
Load: dtoverlay=pwm-ir-tx,<param>=<val>
Params: gpio_pin Output GPIO (default 18)
func Pin function (default 2 = Alt5)
Name: qca7000
Info: I2SE's Evaluation Board for PLC Stamp micro
Load: dtoverlay=qca7000,<param>=<val>
Params: int_pin GPIO pin for interrupt signal (default 23)
speed SPI bus speed (default 12 MHz)
Name: rotary-encoder
Info: Overlay for GPIO connected rotary encoder.
Load: dtoverlay=rotary-encoder,<param>=<val>
Params: pin_a GPIO connected to rotary encoder channel A
(default 4).
pin_b GPIO connected to rotary encoder channel B
(default 17).
relative_axis register a relative axis rather than an
absolute one. Relative axis will only
generate +1/-1 events on the input device,
hence no steps need to be passed.
linux_axis the input subsystem axis to map to this
rotary encoder. Defaults to 0 (ABS_X / REL_X)
rollover Automatic rollover when the rotary value
becomes greater than the specified steps or
smaller than 0. For absolute axis only.
steps-per-period Number of steps (stable states) per period.
The values have the following meaning:
1: Full-period mode (default)
2: Half-period mode
4: Quarter-period mode
steps Number of steps in a full turnaround of the
encoder. Only relevant for absolute axis.
Defaults to 24 which is a typical value for
such devices.
wakeup Boolean, rotary encoder can wake up the
system.
encoding String, the method used to encode steps.
Supported are "gray" (the default and more
common) and "binary".
Name: rpi-backlight
Info: Raspberry Pi official display backlight driver
Load: dtoverlay=rpi-backlight
Params: <None>
Name: rpi-cirrus-wm5102
Info: Configures the Cirrus Logic Audio Card
Load: dtoverlay=rpi-cirrus-wm5102
Params: <None>
Name: rpi-dac
Info: Configures the RPi DAC audio card
Load: dtoverlay=rpi-dac
Params: <None>
Name: rpi-display
Info: RPi-Display - 2.8" Touch Display by Watterott
Load: dtoverlay=rpi-display,<param>=<val>
Params: speed Display SPI bus speed
rotate Display rotation {0,90,180,270}
fps Delay between frame updates
debug Debug output level {0-7}
xohms Touchpanel sensitivity (X-plate resistance)
swapxy Swap x and y axis
backlight Change backlight GPIO pin {e.g. 12, 18}
Name: rpi-ft5406
Info: Official Raspberry Pi display touchscreen
Load: dtoverlay=rpi-ft5406,<param>=<val>
Params: touchscreen-size-x Touchscreen X resolution (default 800)
touchscreen-size-y Touchscreen Y resolution (default 600);
touchscreen-inverted-x Invert touchscreen X coordinates (default 0);
touchscreen-inverted-y Invert touchscreen Y coordinates (default 0);
touchscreen-swapped-x-y Swap X and Y cordinates (default 0);
Name: rpi-poe
Info: Raspberry Pi PoE HAT fan
Load: dtoverlay=rpi-poe,<param>[=<val>]
Params: poe_fan_temp0 Temperature (in millicelcius) at which the fan
turns on (default 40000)
poe_fan_temp0_hyst Temperature delta (in millicelcius) at which
the fan turns off (default 2000)
poe_fan_temp1 Temperature (in millicelcius) at which the fan
speeds up (default 45000)
poe_fan_temp1_hyst Temperature delta (in millicelcius) at which
the fan slows down (default 2000)
poe_fan_temp2 Temperature (in millicelcius) at which the fan
speeds up (default 50000)
poe_fan_temp2_hyst Temperature delta (in millicelcius) at which
the fan slows down (default 2000)
poe_fan_temp3 Temperature (in millicelcius) at which the fan
speeds up (default 55000)
poe_fan_temp3_hyst Temperature delta (in millicelcius) at which
the fan slows down (default 5000)
Name: rpi-proto
Info: Configures the RPi Proto audio card
Load: dtoverlay=rpi-proto
Params: <None>
Name: rpi-sense
Info: Raspberry Pi Sense HAT
Load: dtoverlay=rpi-sense
Params: <None>
Name: rpi-tv
Info: Raspberry Pi TV HAT
Load: dtoverlay=rpi-tv
Params: <None>
Name: rpivid-v4l2
Info: Load the V4L2 stateless video decoder driver for the HEVC block,
disabling the memory mapped devices in the process.
Load: dtoverlay=rpivid-v4l2
Params: <None>
Name: rra-digidac1-wm8741-audio
Info: Configures the Red Rocks Audio DigiDAC1 soundcard
Load: dtoverlay=rra-digidac1-wm8741-audio
Params: <None>
Name: sainsmart18
Info: Overlay for the SPI-connected Sainsmart 1.8" display (based on the
ST7735R chip).
Load: dtoverlay=sainsmart18,<param>=<val>
Params: rotate Display rotation {0,90,180,270}
speed SPI bus speed in Hz (default 4000000)
fps Display frame rate in Hz
bgr Enable BGR mode (default off)
debug Debug output level {0-7}
dc_pin GPIO pin for D/C (default 24)
reset_pin GPIO pin for RESET (default 25)
Name: sc16is750-i2c
Info: Overlay for the NXP SC16IS750 UART with I2C Interface
Enables the chip on I2C1 at 0x48 (or the "addr" parameter value). To
select another address, please refer to table 10 in reference manual.
Load: dtoverlay=sc16is750-i2c,<param>=<val>
Params: int_pin GPIO used for IRQ (default 24)
addr Address (default 0x48)
xtal On-board crystal frequency (default 14745600)
Name: sc16is752-i2c
Info: Overlay for the NXP SC16IS752 dual UART with I2C Interface
Enables the chip on I2C1 at 0x48 (or the "addr" parameter value). To
select another address, please refer to table 10 in reference manual.
Load: dtoverlay=sc16is752-i2c,<param>=<val>
Params: int_pin GPIO used for IRQ (default 24)
addr Address (default 0x48)
xtal On-board crystal frequency (default 14745600)
Name: sc16is752-spi0
Info: Overlay for the NXP SC16IS752 Dual UART with SPI Interface
Enables the chip on SPI0.
Load: dtoverlay=sc16is752-spi0,<param>=<val>
Params: int_pin GPIO used for IRQ (default 24)
xtal On-board crystal frequency (default 14745600)
Name: sc16is752-spi1
Info: Overlay for the NXP SC16IS752 Dual UART with SPI Interface
Enables the chip on SPI1.
N.B.: spi1 is only accessible on devices with a 40pin header, eg:
A+, B+, Zero and PI2 B; as well as the Compute Module.
Load: dtoverlay=sc16is752-spi1,<param>=<val>
Params: int_pin GPIO used for IRQ (default 24)
xtal On-board crystal frequency (default 14745600)
Name: sdhost
Info: Selects the bcm2835-sdhost SD/MMC driver, optionally with overclock.
N.B. This overlay is designed for situations where the mmc driver is
the default, so it disables the other (mmc) interface - this will kill
WiFi on a Pi3. If this isn't what you want, either use the sdtweak
overlay or the new sd_* dtparams of the base DTBs.
Load: dtoverlay=sdhost,<param>=<val>
Params: overclock_50 Clock (in MHz) to use when the MMC framework
requests 50MHz
force_pio Disable DMA support (default off)
pio_limit Number of blocks above which to use DMA
(default 1)
debug Enable debug output (default off)
Name: sdio
Info: Selects the bcm2835-sdhost SD/MMC driver, optionally with overclock,
and enables SDIO via GPIOs 22-27. An example of use in 1-bit mode is
"dtoverlay=sdio,bus_width=1,gpios_22_25"
Load: dtoverlay=sdio,<param>=<val>
Params: sdio_overclock SDIO Clock (in MHz) to use when the MMC
framework requests 50MHz
poll_once Disable SDIO-device polling every second
(default on: polling once at boot-time)
bus_width Set the SDIO host bus width (default 4 bits)
gpios_22_25 Select GPIOs 22-25 for 1-bit mode. Must be used
with bus_width=1. This replaces the sdio-1bit
overlay, which is now deprecated.
gpios_34_37 Select GPIOs 34-37 for 1-bit mode. Must be used
with bus_width=1.
gpios_34_39 Select GPIOs 34-39 for 4-bit mode. Must be used
with bus_width=4 (the default).
Name: sdio-1bit
Info: This overlay is now deprecated. Use
"dtoverlay=sdio,bus_width=1,gpios_22_25" instead.
Load: <Deprecated>
Name: sdtweak
Info: This overlay is now deprecated. Use the sd_* dtparams in the
base DTB, e.g. "dtoverlay=sdtweak,poll_once" becomes
"dtparam=sd_poll_once".
Load: <Deprecated>
Name: seeed-can-fd-hat-v1
Info: Overlay for Seeed Studio CAN BUS FD HAT with two CAN FD channels
(based on the mcp2517fd).
https://www.seeedstudio.com/2-Channel-CAN-BUS-FD-Shield-for-Raspberry-Pi-p-4072.html
Load: dtoverlay=seeed-can-fd-hat-v1
Params: <None>
Name: seeed-can-fd-hat-v2
Info: Overlay for Seeed Studio CAN BUS FD HAT with two CAN FD channels
(based on the mcp2518fd) and an RTC.
https://www.seeedstudio.com/CAN-BUS-FD-HAT-for-Raspberry-Pi-p-4742.html
Load: dtoverlay=seeed-can-fd-hat-v2
Params: <None>
Name: sh1106-spi
Info: Overlay for SH1106 OLED via SPI using fbtft staging driver.
Load: dtoverlay=sh1106-spi,<param>=<val>
Params: speed SPI bus speed (default 4000000)
rotate Display rotation (0, 90, 180 or 270; default 0)
fps Delay between frame updates (default 25)
debug Debug output level (0-7; default 0)
dc_pin GPIO pin for D/C (default 24)
reset_pin GPIO pin for RESET (default 25)
height Display height (32 or 64; default 64)
Name: smi
Info: Enables the Secondary Memory Interface peripheral. Uses GPIOs 2-25!
Load: dtoverlay=smi
Params: <None>
Name: smi-dev
Info: Enables the userspace interface for the SMI driver
Load: dtoverlay=smi-dev
Params: <None>
Name: smi-nand
Info: Enables access to NAND flash via the SMI interface
Load: dtoverlay=smi-nand
Params: <None>
Name: spi-gpio35-39
Info: Move SPI function block to GPIO 35 to 39
Load: dtoverlay=spi-gpio35-39
Params: <None>
Name: spi-gpio40-45
Info: Move SPI function block to GPIOs 40 to 45
Load: dtoverlay=spi-gpio40-45
Params: <None>
Name: spi-rtc
Info: Adds support for a number of SPI Real Time Clock devices
Load: dtoverlay=spi-rtc,<param>=<val>
Params: pcf2123 Select the PCF2123 device
Name: spi0-1cs
Info: Only use one CS pin for SPI0
Load: dtoverlay=spi0-1cs,<param>=<val>
Params: cs0_pin GPIO pin for CS0 (default 8)
no_miso Don't claim and use the MISO pin (9), freeing
it for other uses.
Name: spi0-2cs
Info: Change the CS pins for SPI0
Load: dtoverlay=spi0-2cs,<param>=<val>
Params: cs0_pin GPIO pin for CS0 (default 8)
cs1_pin GPIO pin for CS1 (default 7)
no_miso Don't claim and use the MISO pin (9), freeing
it for other uses.
Name: spi0-cs
Info: This overlay has been renamed spi0-2cs, keeping spi0-cs as an
alias for backwards compatibility.
Load: <Deprecated>
Name: spi0-hw-cs
Info: This overlay has been deprecated and removed because it is no longer
necessary and has been seen to prevent spi0 from working.
Load: <Deprecated>
Name: spi1-1cs
Info: Enables spi1 with a single chip select (CS) line and associated spidev
dev node. The gpio pin number for the CS line and spidev device node
creation are configurable.
N.B.: spi1 is only accessible on devices with a 40pin header, eg:
A+, B+, Zero and PI2 B; as well as the Compute Module.
Load: dtoverlay=spi1-1cs,<param>=<val>
Params: cs0_pin GPIO pin for CS0 (default 18 - BCM SPI1_CE0).
cs0_spidev Set to 'disabled' to stop the creation of a
userspace device node /dev/spidev1.0 (default
is 'okay' or enabled).
Name: spi1-2cs
Info: Enables spi1 with two chip select (CS) lines and associated spidev
dev nodes. The gpio pin numbers for the CS lines and spidev device node
creation are configurable.
N.B.: spi1 is only accessible on devices with a 40pin header, eg:
A+, B+, Zero and PI2 B; as well as the Compute Module.
Load: dtoverlay=spi1-2cs,<param>=<val>
Params: cs0_pin GPIO pin for CS0 (default 18 - BCM SPI1_CE0).
cs1_pin GPIO pin for CS1 (default 17 - BCM SPI1_CE1).
cs0_spidev Set to 'disabled' to stop the creation of a
userspace device node /dev/spidev1.0 (default
is 'okay' or enabled).
cs1_spidev Set to 'disabled' to stop the creation of a
userspace device node /dev/spidev1.1 (default
is 'okay' or enabled).
Name: spi1-3cs
Info: Enables spi1 with three chip select (CS) lines and associated spidev
dev nodes. The gpio pin numbers for the CS lines and spidev device node
creation are configurable.
N.B.: spi1 is only accessible on devices with a 40pin header, eg:
A+, B+, Zero and PI2 B; as well as the Compute Module.
Load: dtoverlay=spi1-3cs,<param>=<val>
Params: cs0_pin GPIO pin for CS0 (default 18 - BCM SPI1_CE0).
cs1_pin GPIO pin for CS1 (default 17 - BCM SPI1_CE1).
cs2_pin GPIO pin for CS2 (default 16 - BCM SPI1_CE2).
cs0_spidev Set to 'disabled' to stop the creation of a
userspace device node /dev/spidev1.0 (default
is 'okay' or enabled).
cs1_spidev Set to 'disabled' to stop the creation of a
userspace device node /dev/spidev1.1 (default
is 'okay' or enabled).
cs2_spidev Set to 'disabled' to stop the creation of a
userspace device node /dev/spidev1.2 (default
is 'okay' or enabled).
Name: spi2-1cs
Info: Enables spi2 with a single chip select (CS) line and associated spidev
dev node. The gpio pin number for the CS line and spidev device node
creation are configurable.
N.B.: spi2 is only accessible with the Compute Module.
Load: dtoverlay=spi2-1cs,<param>=<val>
Params: cs0_pin GPIO pin for CS0 (default 43 - BCM SPI2_CE0).
cs0_spidev Set to 'disabled' to stop the creation of a
userspace device node /dev/spidev2.0 (default
is 'okay' or enabled).
Name: spi2-2cs
Info: Enables spi2 with two chip select (CS) lines and associated spidev
dev nodes. The gpio pin numbers for the CS lines and spidev device node
creation are configurable.
N.B.: spi2 is only accessible with the Compute Module.
Load: dtoverlay=spi2-2cs,<param>=<val>
Params: cs0_pin GPIO pin for CS0 (default 43 - BCM SPI2_CE0).
cs1_pin GPIO pin for CS1 (default 44 - BCM SPI2_CE1).
cs0_spidev Set to 'disabled' to stop the creation of a
userspace device node /dev/spidev2.0 (default
is 'okay' or enabled).
cs1_spidev Set to 'disabled' to stop the creation of a
userspace device node /dev/spidev2.1 (default
is 'okay' or enabled).
Name: spi2-3cs
Info: Enables spi2 with three chip select (CS) lines and associated spidev
dev nodes. The gpio pin numbers for the CS lines and spidev device node
creation are configurable.
N.B.: spi2 is only accessible with the Compute Module.
Load: dtoverlay=spi2-3cs,<param>=<val>
Params: cs0_pin GPIO pin for CS0 (default 43 - BCM SPI2_CE0).
cs1_pin GPIO pin for CS1 (default 44 - BCM SPI2_CE1).
cs2_pin GPIO pin for CS2 (default 45 - BCM SPI2_CE2).
cs0_spidev Set to 'disabled' to stop the creation of a
userspace device node /dev/spidev2.0 (default
is 'okay' or enabled).
cs1_spidev Set to 'disabled' to stop the creation of a
userspace device node /dev/spidev2.1 (default
is 'okay' or enabled).
cs2_spidev Set to 'disabled' to stop the creation of a
userspace device node /dev/spidev2.2 (default
is 'okay' or enabled).
Name: spi3-1cs
Info: Enables spi3 with a single chip select (CS) line and associated spidev
dev node. The gpio pin number for the CS line and spidev device node
creation are configurable. BCM2711 only.
Load: dtoverlay=spi3-1cs,<param>=<val>
Params: cs0_pin GPIO pin for CS0 (default 0 - BCM SPI3_CE0).
cs0_spidev Set to 'off' to prevent the creation of a
userspace device node /dev/spidev3.0 (default
is 'on' or enabled).
Name: spi3-2cs
Info: Enables spi3 with two chip select (CS) lines and associated spidev
dev nodes. The gpio pin numbers for the CS lines and spidev device node
creation are configurable. BCM2711 only.
Load: dtoverlay=spi3-2cs,<param>=<val>
Params: cs0_pin GPIO pin for CS0 (default 0 - BCM SPI3_CE0).
cs1_pin GPIO pin for CS1 (default 24 - BCM SPI3_CE1).
cs0_spidev Set to 'off' to prevent the creation of a
userspace device node /dev/spidev3.0 (default
is 'on' or enabled).
cs1_spidev Set to 'off' to prevent the creation of a
userspace device node /dev/spidev3.1 (default
is 'on' or enabled).
Name: spi4-1cs
Info: Enables spi4 with a single chip select (CS) line and associated spidev
dev node. The gpio pin number for the CS line and spidev device node
creation are configurable. BCM2711 only.
Load: dtoverlay=spi4-1cs,<param>=<val>
Params: cs0_pin GPIO pin for CS0 (default 4 - BCM SPI4_CE0).
cs0_spidev Set to 'off' to prevent the creation of a
userspace device node /dev/spidev4.0 (default
is 'on' or enabled).
Name: spi4-2cs
Info: Enables spi4 with two chip select (CS) lines and associated spidev
dev nodes. The gpio pin numbers for the CS lines and spidev device node
creation are configurable. BCM2711 only.
Load: dtoverlay=spi4-2cs,<param>=<val>
Params: cs0_pin GPIO pin for CS0 (default 4 - BCM SPI4_CE0).
cs1_pin GPIO pin for CS1 (default 25 - BCM SPI4_CE1).
cs0_spidev Set to 'off' to prevent the creation of a
userspace device node /dev/spidev4.0 (default
is 'on' or enabled).
cs1_spidev Set to 'off' to prevent the creation of a
userspace device node /dev/spidev4.1 (default
is 'on' or enabled).
Name: spi5-1cs
Info: Enables spi5 with a single chip select (CS) line and associated spidev
dev node. The gpio pin numbers for the CS lines and spidev device node
creation are configurable. BCM2711 only.
Load: dtoverlay=spi5-1cs,<param>=<val>
Params: cs0_pin GPIO pin for CS0 (default 12 - BCM SPI5_CE0).
cs0_spidev Set to 'off' to prevent the creation of a
userspace device node /dev/spidev5.0 (default
is 'on' or enabled).
Name: spi5-2cs
Info: Enables spi5 with two chip select (CS) lines and associated spidev
dev nodes. The gpio pin numbers for the CS lines and spidev device node
creation are configurable. BCM2711 only.
Load: dtoverlay=spi5-2cs,<param>=<val>
Params: cs0_pin GPIO pin for CS0 (default 12 - BCM SPI5_CE0).
cs1_pin GPIO pin for CS1 (default 26 - BCM SPI5_CE1).
cs0_spidev Set to 'off' to prevent the creation of a
userspace device node /dev/spidev5.0 (default
is 'on' or enabled).
cs1_spidev Set to 'off' to prevent the creation of a
userspace device node /dev/spidev5.1 (default
is 'on' or enabled).
Name: spi6-1cs
Info: Enables spi6 with a single chip select (CS) line and associated spidev
dev node. The gpio pin number for the CS line and spidev device node
creation are configurable. BCM2711 only.
Load: dtoverlay=spi6-1cs,<param>=<val>
Params: cs0_pin GPIO pin for CS0 (default 18 - BCM SPI6_CE0).
cs0_spidev Set to 'off' to prevent the creation of a
userspace device node /dev/spidev6.0 (default
is 'on' or enabled).
Name: spi6-2cs
Info: Enables spi6 with two chip select (CS) lines and associated spidev
dev nodes. The gpio pin numbers for the CS lines and spidev device node
creation are configurable. BCM2711 only.
Load: dtoverlay=spi6-2cs,<param>=<val>
Params: cs0_pin GPIO pin for CS0 (default 18 - BCM SPI6_CE0).
cs1_pin GPIO pin for CS1 (default 27 - BCM SPI6_CE1).
cs0_spidev Set to 'off' to prevent the creation of a
userspace device node /dev/spidev6.0 (default
is 'on' or enabled).
cs1_spidev Set to 'off' to prevent the creation of a
userspace device node /dev/spidev6.1 (default
is 'on' or enabled).
Name: ssd1306
Info: Overlay for activation of SSD1306 over I2C OLED display framebuffer.
Load: dtoverlay=ssd1306,<param>=<val>
Params: address Location in display memory of first character.
(default=0)
width Width of display. (default=128)
height Height of display. (default=64)
offset virtual channel a. (default=0)
normal Has no effect on displays tested. (default=not
set)
sequential Set this if every other scan line is missing.
(default=not set)
remapped Set this if display is garbled. (default=not
set)
inverted Set this if display is inverted and mirrored.
(default=not set)
Examples:
Typical usage for 128x64 display: dtoverlay=ssd1306,inverted
Typical usage for 128x32 display: dtoverlay=ssd1306,inverted,sequential
i2c_baudrate=400000 will speed up the display.
i2c_baudrate=1000000 seems to work even though it's not officially
supported by the hardware, and is faster still.
For more information refer to the device datasheet at:
https://cdn-shop.adafruit.com/datasheets/SSD1306.pdf
Name: ssd1306-spi
Info: Overlay for SSD1306 OLED via SPI using fbtft staging driver.
Load: dtoverlay=ssd1306-spi,<param>=<val>
Params: speed SPI bus speed (default 10000000)
rotate Display rotation (0, 90, 180 or 270; default 0)
fps Delay between frame updates (default 25)
debug Debug output level (0-7; default 0)
dc_pin GPIO pin for D/C (default 24)
reset_pin GPIO pin for RESET (default 25)
height Display height (32 or 64; default 64)
Name: ssd1351-spi
Info: Overlay for SSD1351 OLED via SPI using fbtft staging driver.
Load: dtoverlay=ssd1351-spi,<param>=<val>
Params: speed SPI bus speed (default 4500000)
rotate Display rotation (0, 90, 180 or 270; default 0)
fps Delay between frame updates (default 25)
debug Debug output level (0-7; default 0)
dc_pin GPIO pin for D/C (default 24)
reset_pin GPIO pin for RESET (default 25)
Name: superaudioboard
Info: Configures the SuperAudioBoard sound card
Load: dtoverlay=superaudioboard,<param>=<val>
Params: gpiopin GPIO pin for codec reset
Name: sx150x
Info: Configures the Semtech SX150X I2C GPIO expanders.
Load: dtoverlay=sx150x,<param>=<val>
Params: sx150<x>-<n>-<m> Enables SX150X device on I2C#<n> with slave
address <m>. <x> may be 1-9. <n> may be 0 or 1.
Permissible values of <m> (which is denoted in
hex) depend on the device variant. For SX1501,
SX1502, SX1504 and SX1505, <m> may be 20 or 21.
For SX1503 and SX1506, <m> may be 20. For
SX1507 and SX1509, <m> may be 3E, 3F, 70 or 71.
For SX1508, <m> may be 20, 21, 22 or 23.
sx150<x>-<n>-<m>-int-gpio
Integer, enables interrupts on SX150X device on
I2C#<n> with slave address <m>, specifies
the GPIO pin to which NINT output of SX150X is
connected.
Name: tc358743
Info: Toshiba TC358743 HDMI to CSI-2 bridge chip.
Uses Unicam 1, which is the standard camera connector on most Pi
variants.
Load: dtoverlay=tc358743,<param>=<val>
Params: 4lane Use 4 lanes (only applicable to Compute Modules
CAM1 connector).
link-frequency Set the link frequency. Only values of 297000000
(574Mbit/s) and 486000000 (972Mbit/s - default)
are supported by the driver.
Name: tc358743-audio
Info: Used in combination with the tc358743-fast overlay to route the audio
from the TC358743 over I2S to the Pi.
Wiring is LRCK/WFS to GPIO 19, BCK/SCK to GPIO 18, and DATA/SD to GPIO
20.
Load: dtoverlay=tc358743-audio,<param>=<val>
Params: card-name Override the default, "tc358743", card name.
Name: tinylcd35
Info: 3.5" Color TFT Display by www.tinylcd.com
Options: Touch, RTC, keypad
Load: dtoverlay=tinylcd35,<param>=<val>
Params: speed Display SPI bus speed
rotate Display rotation {0,90,180,270}
fps Delay between frame updates
debug Debug output level {0-7}
touch Enable touch panel
touchgpio Touch controller IRQ GPIO
xohms Touchpanel: Resistance of X-plate in ohms
rtc-pcf PCF8563 Real Time Clock
rtc-ds DS1307 Real Time Clock
keypad Enable keypad
Examples:
Display with touchpanel, PCF8563 RTC and keypad:
dtoverlay=tinylcd35,touch,rtc-pcf,keypad
Old touch display:
dtoverlay=tinylcd35,touch,touchgpio=3
Name: tpm-slb9670
Info: Enables support for Infineon SLB9670 Trusted Platform Module add-on
boards, which can be used as a secure key storage and hwrng,
available as "Iridium SLB9670" by Infineon and "LetsTrust TPM" by pi3g.
Load: dtoverlay=tpm-slb9670
Params: <None>
Name: uart0
Info: Change the pin usage of uart0
Load: dtoverlay=uart0,<param>=<val>
Params: txd0_pin GPIO pin for TXD0 (14, 32 or 36 - default 14)
rxd0_pin GPIO pin for RXD0 (15, 33 or 37 - default 15)
pin_func Alternative pin function - 4(Alt0) for 14&15,
7(Alt3) for 32&33, 6(Alt2) for 36&37
Name: uart1
Info: Change the pin usage of uart1
Load: dtoverlay=uart1,<param>=<val>
Params: txd1_pin GPIO pin for TXD1 (14, 32 or 40 - default 14)
rxd1_pin GPIO pin for RXD1 (15, 33 or 41 - default 15)
Name: uart2
Info: Enable uart 2 on GPIOs 0-3. BCM2711 only.
Load: dtoverlay=uart2,<param>
Params: ctsrts Enable CTS/RTS on GPIOs 2-3 (default off)
Name: uart3
Info: Enable uart 3 on GPIOs 4-7. BCM2711 only.
Load: dtoverlay=uart3,<param>
Params: ctsrts Enable CTS/RTS on GPIOs 6-7 (default off)
Name: uart4
Info: Enable uart 4 on GPIOs 8-11. BCM2711 only.
Load: dtoverlay=uart4,<param>
Params: ctsrts Enable CTS/RTS on GPIOs 10-11 (default off)
Name: uart5
Info: Enable uart 5 on GPIOs 12-15. BCM2711 only.
Load: dtoverlay=uart5,<param>
Params: ctsrts Enable CTS/RTS on GPIOs 14-15 (default off)
Name: udrc
Info: Configures the NW Digital Radio UDRC Hat
Load: dtoverlay=udrc,<param>=<val>
Params: alsaname Name of the ALSA audio device (default "udrc")
Name: upstream
Info: Allow usage of downstream .dtb with upstream kernel. Comprises the
vc4-kms-v3d and dwc2 overlays.
Load: dtoverlay=upstream
Params: <None>
Name: upstream-aux-interrupt
Info: This overlay has been deprecated and removed because it is no longer
necessary.
Load: <Deprecated>
Name: upstream-pi4
Info: Allow usage of downstream .dtb with upstream kernel on Pi 4. Comprises
the vc4-kms-v3d-pi4 and dwc2 overlays.
Load: dtoverlay=upstream-pi4
Params: <None>
Name: vc4-fkms-v3d
Info: Enable Eric Anholt's DRM VC4 V3D driver on top of the dispmanx
display stack.
Load: dtoverlay=vc4-fkms-v3d,<param>
Params: cma-512 CMA is 512MB (needs 1GB)
cma-448 CMA is 448MB (needs 1GB)
cma-384 CMA is 384MB (needs 1GB)
cma-320 CMA is 320MB (needs 1GB)
cma-256 CMA is 256MB (needs 1GB)
cma-192 CMA is 192MB (needs 1GB)
cma-128 CMA is 128MB
cma-96 CMA is 96MB
cma-64 CMA is 64MB
cma-size CMA size in bytes, 4MB aligned
cma-default Use upstream's default value
Name: vc4-kms-dsi-7inch
Info: Enable the Raspberry Pi DSI 7" screen.
Use edt-ft5406 for the touchscreen element.
Requires vc4-kms-v3d to be loaded.
Load: dtoverlay=vc4-kms-dsi-7inch
Params: <None>
Name: vc4-kms-kippah-7inch
Info: Enable the Adafruit DPI Kippah with the 7" Ontat panel attached.
Requires vc4-kms-v3d to be loaded.
Load: dtoverlay=vc4-kms-kippah-7inch
Params: <None>
Name: vc4-kms-v3d
Info: Enable Eric Anholt's DRM VC4 HDMI/HVS/V3D driver.
Load: dtoverlay=vc4-kms-v3d,<param>
Params: cma-512 CMA is 512MB (needs 1GB)
cma-448 CMA is 448MB (needs 1GB)
cma-384 CMA is 384MB (needs 1GB)
cma-320 CMA is 320MB (needs 1GB)
cma-256 CMA is 256MB (needs 1GB)
cma-192 CMA is 192MB (needs 1GB)
cma-128 CMA is 128MB
cma-96 CMA is 96MB
cma-64 CMA is 64MB
cma-size CMA size in bytes, 4MB aligned
cma-default Use upstream's default value
audio Enable or disable audio over HDMI (default "on")
noaudio Disable all HDMI audio (default "off")
nocomposite Disable the composite video output (default
"off")
Name: vc4-kms-v3d-pi4
Info: Enable Eric Anholt's DRM VC4 HDMI/HVS/V3D driver for Pi4.
Load: dtoverlay=vc4-kms-v3d-pi4,<param>
Params: cma-512 CMA is 512MB
cma-448 CMA is 448MB
cma-384 CMA is 384MB
cma-320 CMA is 320MB
cma-256 CMA is 256MB
cma-192 CMA is 192MB
cma-128 CMA is 128MB
cma-96 CMA is 96MB
cma-64 CMA is 64MB
cma-size CMA size in bytes, 4MB aligned
cma-default Use upstream's default value
audio Enable or disable audio over HDMI0 (default
"on")
audio1 Enable or disable audio over HDMI1 (default
"on")
noaudio Disable all HDMI audio (default "off")
composite Enable the composite output (disables all other
outputs)
Name: vga666
Info: Overlay for the Fen Logic VGA666 board
This uses GPIOs 2-21 (so no I2C), and activates the output 2-3 seconds
after the kernel has started.
Load: dtoverlay=vga666
Params: <None>
Name: w1-gpio
Info: Configures the w1-gpio Onewire interface module.
Use this overlay if you *don't* need a GPIO to drive an external pullup.
Load: dtoverlay=w1-gpio,<param>=<val>
Params: gpiopin GPIO for I/O (default "4")
pullup Now enabled by default (ignored)
Name: w1-gpio-pullup
Info: Configures the w1-gpio Onewire interface module.
Use this overlay if you *do* need a GPIO to drive an external pullup.
Load: dtoverlay=w1-gpio-pullup,<param>=<val>
Params: gpiopin GPIO for I/O (default "4")
extpullup GPIO for external pullup (default "5")
pullup Now enabled by default (ignored)
Name: w5500
Info: Overlay for the Wiznet W5500 Ethernet Controller on SPI0
Load: dtoverlay=w5500,<param>=<val>
Params: int_pin GPIO used for INT (default 25)
speed SPI bus speed (default 30000000)
cs SPI bus Chip Select (default 0)
Name: wittypi
Info: Configures the wittypi RTC module.
Load: dtoverlay=wittypi,<param>=<val>
Params: led_gpio GPIO for LED (default "17")
led_trigger Choose which activity the LED tracks (default
"default-on")
Name: wm8960-soundcard
Info: Overlay for the Waveshare wm8960 soundcard
Load: dtoverlay=wm8960-soundcard,<param>=<val>
Params: alsaname Changes the card name in ALSA
compatible Changes the codec compatibility
If you are experiencing problems that you think are DT-related, enable DT diagnostic output by adding this to /boot/config.txt:
dtdebug=on
and rebooting. Then run:
sudo vcdbg log msg
and look for relevant messages.
This is only meant to be a quick introduction to the subject of Device Tree on Raspberry Pi. There is a more complete explanation here:
http://www.raspberrypi.org/documentation/configuration/device-tree.md