Sleep and Wake up by GPIO

[JIYEON]

Hello,

My board is connected to Gyro, Magneto sensor.

And board is sleep and wake-up by GPIO.

It usually works well. But time to time after wake-up from sleep mode, sensor data read wired.

In below picture, from -800 to -400, same value is read although sensor is shaken.

After power reset at -400, sensor data is read well again.

I checked sensor configuration with sensor company. They confirmed that it looks fine and suggest me to check difference between wake-up from sleep and power reset.

In 18.8 Reset behavior, It specified that GPIO and SWJ-DP, WDT, Retained register, RESETREAS isn't reset.

"sleep_mode_enter" function is called when sleep interrupt is triggered from Gyro sensor.

void sleep_mode_enter(void)
{
   uint32_t err_code;

   NRF_LOG_INFO("Entering sleep mode \r\n");
   nrf_delay_ms(15);

   // Enable wake on low power accelerometer.
   nrf_gpio_cfg_sense_input(PIN_LSM_INT2, NRF_GPIO_PIN_PULLDOWN, NRF_GPIO_PIN_SENSE_HIGH);

   //Enter System-off
   nrf_pwr_mgmt_shutdown(NRF_PWR_MGMT_SHUTDOWN_STAY_IN_SYSOFF);
   nrf_delay_ms(15);

   NRF_LOG_INFO("sd_power_system_off() returned. -Probably due to debugger being used. Instructions will still run. \r\n");

}

Could I configure wake-up work like power reset?

[Jared]

Hi,

They confirmed that it looks fine and suggest me to check difference between wake-up from sleep and power reset.

The difference between a wakeup from System Off sleep versus a Power-On-Reset is that the GPIO peripheral is reset only in the latter case. The GPIO peripheral is not reset after a wakeup from System Off sleep, it will instead retain its configuration. Which means that it will retain the configuration you set right before you go to sleep when it wakes up.

Hope it helps.

regards

Jared