Enter in SYSTEM ON doest not work

[Louis Hatte]

Hello everyone,

I'm using the nrf52840 Dev Kit (PCA10056 1.1.0 2019.19 683465548)

SDK version: 15.3

OS: Fedora

I work on a custom board and try to put it in SYSTEM ON mode like so:

int main(void)
{
    log_init();
    NRF_LOG_INFO("App start\n");
    NRF_LOG_FLUSH();

    power_management_init();
    for (;;) {
        nrf_pwr_mgmt_run();
    }
}

When I measure my consommation with OTII I get 4 mA instead of 1.5 uA according to this link (Debugging: Section 4).

Any ideas?

Regards,

Louis

[Louis Hatte]

Hey Simonr,

Thanks for your help

We have switched back to the NRF52 DK to reproduce your test and we had 4µA with RTT logging only. It's still not the 2.3µA you have, but it's good enough for us. 
From this solid base, we have tried to gradually re-implement our project in this template to see what draws current. 

When using the UART Driver (APP_UART_FIFO_INIT) followed by app_uart_close to the peripheral, we have about 890µA when we expect to have the 4µA measured just before. 

We have found many post on this subject, but none answered....

How to correctly use the UART Driver for low power consumption ?

Thanks