Backend UART (log) crashs when system shutdowns

Question

Hi,

I have a crash in the LOG backend UART when the system shutdowns:

<info> app: poweroff...
<debug> app: Disconnected connection handle 0
<info> app: Disconnected 1 links.
<info> pwr_mgmt: Shutdown request 0
<info> pwr_mgmt: Shutdown started. Type 0
<info> app: NRF_PWR_MGMT_EVT_PREPARE_WAKEUP
<info> pwr_mgmt: SysOff handler 0x00030775 => ready
<info> pwr_mgmt: Maximum CPU usage: 74%
<info> p<info> pwr_mgmt: Shutdown complete.
<debug> nrf_sdh_ble: BLE event: 0x11.
<error> app: ERROR 17 [NRF_ERROR_BUSY] at sdk-nrf52/components/libraries/log/src/nrf_log_backend_uart.c:83                                                                                                        
PC at: 0x0002649B
<error> app: End of error report

My power manager handler is as follows:

static bool app_shutdown_handler(nrf_pwr_mgmt_evt_t event)
{
    uint32_t err_code;

    switch (event)
    {
        case NRF_PWR_MGMT_EVT_PREPARE_WAKEUP:
                NRF_LOG_INFO("NRF_PWR_MGMT_EVT_PREPARE_WAKEUP");

                //Configure the sense to be woken up on push.
                nrf_gpio_cfg_sense_input(INT_BTN_USB,
                                         NRF_GPIO_PIN_NOPULL,
                                         NRF_GPIO_PIN_SENSE_LOW);

                NRF_LOG_FINAL_FLUSH();
                return true;
                break;

        default:
            return true;
    }

    return true;
}

The crash occurs when the backend calls nrf_drv_uart_tx() that returns BUSY. I've tried to call NRF_LOG_FINAL_FLUSH() but the problem is still present. Is there a way to avoid this crash ? I did not see any way to disable the backend.

I use a NRF52832 and the SDK V15.2. Logs are deferred and the main calls NRF_LOG_PROCESS() in a while loop to empty the queue.

Best regards,

Mathieu

Simonr · Accepted Answer

Hi Mathieu, 
 I regret to inform you that you must expect delays in response during the holiday season due to reduced support capacity, but I will get back to you during the first week of January 2019. 
 I wish you a merry Christmas and a happy new year! 
 Simon

Backend UART (log) crashs when system shutdowns

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