STM32sleep

Helper library for using Stop & Standby modes with STM32duino on STM32F103Cx microcontrollers.

Usage

1. Install STM32duino
2. Create STM32sleep directory under Arduino IDE's library dir (~Documents/Arduino/libraries on OS X)
3. Clone all files in this repository to the created directory
4. Restart Arduino IDE if it was running
5. Include STM32Sleep.h and RTClock.h to your sketch
6. Code away!

Examples

Standby mode

The following code runs the microcontroller normally for 1 second and then sleeps 5 seconds in standby mode. When RTC alarm triggers, the device is reset and the sketch runs again from the beginning.

#include <STM32Sleep.h>
#include <RTClock.h>

RTClock rt(RTCSEL_LSE);
long int alarmDelay = 5;

void setup() {
  // We have just started or woken up from sleep! System clock is set to 72MHz HSE.
  delay(1000);
  sleepAndWakeUp(STANDBY, &rt, alarmDelay);  
}

void loop() { }  // This is never run

Stop mode

The following sketch disables ADC & GPIO's to save power before entering stop mode. Device is then continuously woken up after 5 seconds by RTC.

#include <STM32Sleep.h>
#include <RTClock.h>

RTClock rt(RTCSEL_LSE);
long int alarmDelay = 5;

void setup() {
  // Disable ADC to save power
  adc_disable_all();

  // Set all GPIO pins to Analog input to save power (this disables pretty 
  // much all I/O incl. Serial)
  setGPIOModeToAllPins(GPIO_INPUT_ANALOG);  

  sleepAndWakeUp(STOP, &rt, alarmDelay);
}

void loop() {
  // We have woken up from sleep! System clock is set to 8MHz HSI.
  
  // Optionally disable peripheral clocks to save power while in Run mode
  //disableAllPeripheralClocks();

  delay(100);  // As the main clock is only 8MHz instead of normal 72MHz this actually takes 900ms

  sleepAndWakeUp(STOP, &rt, alarmDelay);
}

#Misc

Thanks for the hard work & inspiration for all the people working on STM32duino!

For more about low power on STM32 devices, see e.g. Low power mode and wake from sleep.