Posted on July 02, 2018 at 19:13Hi,
I am working with an STM32L4. I'm trying to put it into STANDBY mode, and wake it up using a WKUP pin. The issue is that the first time I go to standby after POR, the system wakes up immediately, though I'm sure none of the wakeup pins have had an edge transition. If I go back to STANDBY after that, the system stays in STANDBY. Can anyone explain this behavior? For what it's worth, I am not using a watchdog, I'm turning off the GPIO clocks before going to STANDBY, and I am clearing the standby and WUF flags on every reset. I am including my code for clearing the flags and going to STANDBY.
Thanks,
Ricardo
/* Code for clearing flags, run on every reset */
void SystemStartup(void) {
uint8_t reason = 0;
/* Check if the system was resumed from Standby mode */
if (__HAL_PWR_GET_FLAG(PWR_FLAG_SB) != RESET) {
/* Clear Standby flag */
__HAL_PWR_CLEAR_FLAG(PWR_FLAG_SB);
reason |= 0x80;
}
/* Check and Clear the Wakeup flag */
if (__HAL_PWR_GET_FLAG(PWR_FLAG_WUF1) != RESET) {
__HAL_PWR_CLEAR_FLAG(PWR_FLAG_WUF1);
reason |= 0x01;
}
if (__HAL_PWR_GET_FLAG(PWR_FLAG_WUF2) != RESET) {
__HAL_PWR_CLEAR_FLAG(PWR_FLAG_WUF2);
reason |= 0x02;
}
if (__HAL_PWR_GET_FLAG(PWR_FLAG_WUF3) != RESET) {
__HAL_PWR_CLEAR_FLAG(PWR_FLAG_WUF3);
reason |= 0x04;
}
if (__HAL_PWR_GET_FLAG(PWR_FLAG_WUF5) != RESET) {
__HAL_PWR_CLEAR_FLAG(PWR_FLAG_WUF5);
reason |= 0x80;
}
}
/* code for going to STANDBY mode */
void PowerManager::EnterSleepState(void) {
// Wakeup when Qi Charger stops charging - Note CHG♯ is active low
HAL_PWR_EnableWakeUpPin(PWR_WAKEUP_PIN1_HIGH);
// Wakeup when device is latched
HAL_PWR_EnableWakeUpPin(PWR_WAKEUP_PIN2_HIGH);
// Wakeup when a BLE packet is received
HAL_PWR_EnableWakeUpPin(PWR_WAKEUP_PIN3_HIGH);
// Wakeup when the user taps the device (accelerometer interrupt)
HAL_PWR_EnableWakeUpPin(PWR_WAKEUP_PIN5_HIGH);
sysSerial.Print('Going down\r\n');
// Disable GPIO clocks
__HAL_RCC_GPIOA_CLK_DISABLE();
__HAL_RCC_GPIOB_CLK_DISABLE();
__HAL_RCC_GPIOC_CLK_DISABLE();
__HAL_RCC_GPIOD_CLK_DISABLE();
__HAL_RCC_GPIOE_CLK_DISABLE();
__HAL_RCC_GPIOF_CLK_DISABLE();
__HAL_RCC_GPIOG_CLK_DISABLE();
__HAL_RCC_GPIOH_CLK_DISABLE();
__HAL_RCC_GPIOI_CLK_DISABLE();
// Enter STANDBY mode -
HAL_PWR_EnterSTANDBYMode();
// The rest of this function should never be executed, as the MCU will reset upon wakeup
__HAL_RCC_GPIOA_CLK_ENABLE();
__HAL_RCC_GPIOB_CLK_ENABLE();
__HAL_RCC_GPIOC_CLK_ENABLE();
__HAL_RCC_GPIOD_CLK_ENABLE();
__HAL_RCC_GPIOE_CLK_ENABLE();
__HAL_RCC_GPIOF_CLK_ENABLE();
__HAL_RCC_GPIOG_CLK_ENABLE();
__HAL_RCC_GPIOH_CLK_ENABLE();
__HAL_RCC_GPIOI_CLK_ENABLE();
sysSerial.Print('Getting up\r\n');
// reconfigure the system clock
SystemClock_Config();
// reenable I/O
HAL_PWR_DisableWakeUpPin(PWR_WAKEUP_PIN1_HIGH);
HAL_PWR_DisableWakeUpPin(PWR_WAKEUP_PIN2_HIGH);
HAL_PWR_DisableWakeUpPin(PWR_WAKEUP_PIN3_HIGH);
HAL_PWR_DisableWakeUpPin(PWR_WAKEUP_PIN5_HIGH);
}
#standby-mode
