nRF5_SDK_15.3.0 cannot enter low power

[libailiang]

Hi 

When I use the nRF5_SDK_15.3.0, the nRF52832 cannot enter low power (about 900uA). The example is file ble_app_blinky. 

The main code is as following:

int main(void)
{
    // Initialize.
    log_init();
    leds_init();
    timers_init();
    buttons_init();
    power_management_init();
    ble_stack_init();
    gap_params_init();
    gatt_init();
    services_init();
    advertising_init();
    conn_params_init();

   // Start execution.
   NRF_LOG_INFO("Blinky example started.");
   advertising_start();

   // Enter main loop.
   for (;;)
   {
       idle_state_handle();
    }
}

Could you give me some advice. Thanks.

[Einar Thorsrud]

Hi,

A typical reason for high current consumption with the SDK examples is that you have not disabled UART logging. Make sure that you have set NRF_LOG_ENABLED to 0 (alternatively only set NRF_LOG_BACKEND_UART_ENABLED to 0 if you want to use RTT logging instead (by setting NRF_LOG_BACKEND_RTT_ENABLED to 1). Does that help?

[Gurel]

Hi Einar,

I had the same problem with my custom board using NRF52840 and setting NRF_LOG_ENABLED to 0 reduced my current consumption from 2.7mA to ~60uA. Btw the minumum current consumpion I saw was ~21uA when running the code below.

int main(void)
{
  for(;;){
    __WFE();
    __SEV();
    __WFE();
  }
}

I should also state that my multimeter is not super sensitive but still not bad.

So my application is very similar to the ble_app_blinky application and I'm wondering if Is it possible to reduce the current consumption even more?

[Einar Thorsrud]

Hi,

Looking at your code snippet, there is nothing you can do in SW to reduce this further (other than system off mode). But the current consumption is too high. The nRF itself should consume about 2 μA in this case, as it is basically not doing anything other than staying in low power sleep mode. I would consider if there could there be other components on your PCB drawing the additional current? Is it possible to measure only the current consumption of the nRF? If not, try measuring with a better instrument.

(note that the current consumption of the nRF52 in sleep mode is bursty, due to the LDO refresh mode. So some instruments may not be able to average the current consumption correctly.)