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interfaces.md

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Hardware Interfaces

Referring to the Comportable guideline for peripheral device functionality, the module usbdev has the following hardware interfaces defined

  • Primary Clock: clk_i
  • Other Clocks: clk_aon_i
  • Bus Device Interfaces (TL-UL): tl
  • Bus Host Interfaces (TL-UL): none

Peripheral Pins for Chip IO

Pin name Direction Description
sense input USB host VBUS sense
usb_dp inout USB data D+
usb_dn inout USB data D-

Inter-Module Signals

Port Name Package::Struct Type Act Width Description
usb_rx_d logic uni rcv 1 USB RX data from an external differential receiver, if available
usb_tx_d logic uni req 1 USB transmit data value (not used if usb_tx_se0 is set)
usb_tx_se0 logic uni req 1 Force transmission of a USB single-ended zero (i.e. both D+ and D- are low) regardless of usb_tx_d
usb_tx_use_d_se0 logic uni req 1 Use the usb_tx_d and usb_tx_se0 TX interface, instead of usb_dp_o and usb_dn_o
usb_dp_pullup logic uni req 1 USB D+ pullup control
usb_dn_pullup logic uni req 1 USB D- pullup control
usb_rx_enable logic uni req 1 USB differential receiver enable
usb_ref_val logic uni req 1
usb_ref_pulse logic uni req 1
usb_aon_suspend_req logic uni req 1
usb_aon_wake_ack logic uni req 1
usb_aon_bus_reset logic uni rcv 1
usb_aon_sense_lost logic uni rcv 1
usb_aon_wake_detect_active logic uni rcv 1
ram_cfg prim_ram_2p_pkg::ram_2p_cfg uni rcv 1
tl tlul_pkg::tl req_rsp rsp 1

Interrupts

Interrupt Name Type Description
pkt_received Event Raised if a packet was received using an OUT or SETUP transaction. This interrupt is directly tied to whether the RX FIFO is empty, so it should be cleared only after handling the FIFO entry.
pkt_sent Event Raised if a packet was sent as part of an IN transaction. This interrupt is directly tied to whether a sent packet has not been acknowledged in the in_sent register. It should be cleared only after clearing all bits in the in_sent register.
disconnected Event Raised if VBUS is lost thus the link is disconnected.
host_lost Event Raised if link is active but SOF was not received from host for 4.096 ms. The SOF should be every 1 ms.
link_reset Event Raised if the link is at SE0 longer than 3 us indicating a link reset (host asserts for min 10 ms, device can react after 2.5 us).
link_suspend Event Raised if the line has signaled J for longer than 3ms and is therefore in suspend state.
link_resume Event Raised when the link becomes active again after being suspended.
av_empty Event Raised when the AV FIFO is empty and the device interface is enabled. This interrupt is directly tied to the FIFO status, so the AV FIFO must be provided a free buffer before the interrupt is cleared. If the condition is not cleared, the interrupt can re-assert.
rx_full Event Raised when the RX FIFO is full and the device interface is enabled. This interrupt is directly tied to the FIFO status, so the RX FIFO must have an entry removed before the interrupt is cleared. If the condition is not cleared, the interrupt can re-assert.
av_overflow Event Raised if a write was done to the Available Buffer FIFO when the FIFO was full.
link_in_err Event Raised if a packet to an IN endpoint started to be received but was then dropped due to an error. After transmitting the IN payload, the USB device expects a valid ACK handshake packet. This error is raised if either the packet or CRC is invalid or a different token was received.
rx_crc_err Event Raised if a CRC error occured.
rx_pid_err Event Raised if an invalid packed identifier (PID) was received.
rx_bitstuff_err Event Raised if an invalid bitstuffing was received.
frame Event Raised when the USB frame number is updated with a valid SOF.
powered Event Raised if VBUS is applied.
link_out_err Event Raised if a packet to an OUT endpoint started to be received but was then dropped due to an error. This error is raised if the data toggle, token, packet and/or CRC are invalid, if the Available Buffer FIFO is empty or if the Received Buffer FIFO is full.

Security Alerts

Alert Name Description
fatal_fault This fatal alert is triggered when a fatal TL-UL bus integrity fault is detected.

Security Countermeasures

Countermeasure ID Description
USBDEV.BUS.INTEGRITY End-to-end bus integrity scheme.