SPIS not working with nrf_pwr_mgmt_run

[M. David.]

Hey all

In my current project I could set up an SPI communication, where the SPI-slave is on the nordic side. This works fine when I have __WFE() in my main loop, however when I replace __WFE() by nrf_pwr_mgmt_run() no SPI data is received anymore.

    while (true) // endless main loop
    {
        if(NRF_LOG_PROCESS() == false)
        {
//            __WFE();
            nrf_pwr_mgmt_run();
        }
    }

Can anyone give me a hint, why this does not work? And whats the

[Simonr]

Hi

In our SPIS example project, we enable constant latency mode on startup in order to mitigate this (see snippet below). It should also be okay to add a delay of ~10us between CS low and the first clock cycle for instance.

    // Enable the constant latency sub power mode to minimize the time it takes
    // for the SPIS peripheral to become active after the CSN line is asserted
    // (when the CPU is in sleep mode).
    NRF_POWER->TASKS_CONSTLAT = 1;

Best regards,

Simon