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STM32LowPower

Arduino library to support STM32 Low Power.

Requirement

API

  • void begin(): configure the Low Power

  • void idle(uint32_t ms): enter in idle mode param ms (optional): number of milliseconds before to exit the mode. The RTC is used in alarm mode to wakeup the chip in ms milliseconds.

  • void sleep(uint32_t ms): enter in sleep mode param ms (optional): number of milliseconds before to exit the mode. The RTC is used in alarm mode to wakeup the chip in ms milliseconds.

  • void deepSleep(uint32_t ms): enter in deepSleep mode param ms (optional): number of milliseconds before to exit the mode. The RTC is used in alarm mode to wakeup the chip in ms milliseconds.

  • void shutdown(uint32_t ms): enter in shutdown mode param ms (optional): number of milliseconds before to exit the mode. The RTC is used in alarm mode to wakeup the board in ms milliseconds.

Note

With STM32RTC version lower than 1.1.0, the minimum number of milliseconds is 1000 ms.**

  • void attachInterruptWakeup(uint32_t pin, voidFuncPtrVoid callback, uint32_t mode, LP_Mode LowPowerMode): Enable GPIO pin in interrupt mode. If the pin is a wakeup pin, it is configured as wakeup source (see board documentation). param pin: pin number
    param callback: pointer to callback
    param mode: interrupt mode (HIGH, LOW, RISING, FALLING or CHANGE) param LowPowerMode: Low power mode which will be used (IDLE_MODE, SLEEP_MODE, DEEP_SLEEP_MODE or SHUTDOWN_MODE). In case of SHUTDOWN_MODE only, Wakeup pin capability is activated.

  • void enableWakeupFrom(HardwareSerial *serial, voidFuncPtrVoid callback): enable a UART peripheral in low power mode. See board documentation for low power mode compatibility.
    param serial: pointer to a UART
    param callback: pointer to a callback to call when the board is waked up.

  • void enableWakeupFrom(STM32RTC *rtc, voidFuncPtr callback, void * data) attach a callback to the RTC peripheral.
    param rtc: pointer to RTC. Could be NULL as RTC is a Singleton.
    param callback: pointer to a callback to call when the board is waked up.
    param callback: data: optional pointer to callback data parameters (default NULL).

  • void enableWakeupFrom(TwoWire *wire, voidFuncPtrVoid callback): enable an I2C peripheral in low power mode. See board documentation for low power mode compatibility. Currently not available.
    param wire: pointer to I2C
    param callback: pointer to a callback to call when the board is waked up.

Begin() function must be called at least once before idle(), sleep(), deepSleep() or shutdown() functions.

attachInterruptWakeup() or enableWakeupFrom() functions should be called before idle(), sleep(), deepSleep() or shutdown() functions.

Important

  • HardwareSerial used as Wakeup source will configure it to use HSI clock source even if another peripheral clock is configured.

  • RTC used as Wakeup source requires to have LSE or LSI as clock source. If one of them is used nothing is changed else it will configure it to use LSI clock source. One exception exists when SHUTDOWN_MODE is requested and PWR_CR1_LPMS is defined, in that case LSE is required. So, if the board does not have LSE, it will fail.

  • The board will restart when exit shutdown mode.

Hardware state

  • Idle mode: low wake-up latency (µs range) (e.g. ARM WFI). Memories and voltage supplies are retained. Minimal power saving mainly on the core itself.

  • sleep mode: low wake-up latency (µs range) (e.g. ARM WFI), Memories and voltage supplies are retained. Minimal power saving mainly on the core itself but higher than idle mode.

  • deep sleep mode: medium latency (ms range), clocks are gated to reduced. Memories and voltage supplies are retained. If supported, Peripherals wake-up is possible (UART, I2C ...).

  • shutdown mode: high wake-up latency (possible hundereds of ms or second timeframe), voltage supplies are cut except always-on domain, memory content are lost and system basically reboots.

Source

You can find the source files at
https://github.com/stm32duino/STM32LowPower