how to wake up from sleep mode

[ps_anu]

hi.....

i am using nrf52832 ........

i want to wake up my device from sleep mode ... i have used the command for sleep mode sd_app_evt_wait() ...... i dono  what command to give for waking up device from sleep mode 

thanks in advance

suggest me an answer

[Einar Thorsrud]

Hi,

The sd_app_evt_wait() calls __WFE() internally (among other things), so the nRF will wake up on any event/interrupt. A typical wake up source is a RTC compare event or GPIO input interrupt, but it could be anything.

[ps_anu]

 i have called sd_app_evt_wait() in main loop 

but it doesn't go to sleep 

/**@brief Application main function.
 */
int main(void)

{
    bool erase_bonds;

    // Initialize.
    uart_init();
    log_init();
    timers_init();
    buttons_leds_init(&erase_bonds);
    power_management_init();
    ble_stack_init();
    gap_params_init();
    gatt_init();
    services_init();
    advertising_init();
    conn_params_init();
    


    // Start execution.
    printf("\r\nUART started.\r\n");
    NRF_LOG_INFO("Debug logging for UART over RTT started.");
    advertising_start();
    
    twi_init();
    LM75B_set_mode();
    
      while (true)
    {
        nrf_delay_ms(5000);

        do
        {
            __WFE();
        }while (m_xfer_done == false);
      
     
       
        // read_sensor_data();
       //  power_manage();
         threshold_value();
      sd_app_evt_wait();
        NRF_LOG_FLUSH();
    }
    }

help me 

[Einar Thorsrud]

Looking at your code snippets I see there are a number of misunderstandings here:

• You have to read data via TWI to see if the temperature has crossed the threshold. So clearly the nRF cannot wake on that event, as the only way it can know about it is to wake up regularly and read the sensor.
• You do a busy wait in your main loop, which waits by spending CPU cycles. This means that your application will spend 5 seconds consuming a lot of power while doing nothing for every iteration of your main loop.
• The sd_app_evt_wait() call should cause the CPU to sleep for a bit of time, but only until the TWI transaction has finished. All the rest of your waiting happens in the busy wait (sd_app_evt_wait()).

The proper way to do what you want is to have a main loop which does close to nothing other than calling sd_app_evt_wait(). Then you should use a low power timer (RTC), typically via the timer library to read the sensor at a regular interval.

[ps_anu]

how to wake up the nrf 

[Einar Thorsrud]

I suggest you use the app_timer (timer library).

[ps_anu]

ok ... how you know that device in sleep mode ?

by measuring current or checking data

[Einar Thorsrud]

Yes, measuring current consumption is the simplest and best way.