The correct procedure to uninit uarte then reinitialize it

[esonhon]

I'm developing a project that use BLE advertise and uart communication with other uC.

The uart part is based on libuarte example. To decrease the current consumption, I think we must uninit uarte before system sleep, then reinitialize it when wakeup.

void uc_deInit()
{
  if(uartInited){
    nrf_libuarte_async_uninit(&libuarte);
 
  //when uarte inited then uninit, current consumption keep higher about 0.8ma, workarounds below
  //@refers https://devzone.nordicsemi.com/f/nordic-q-a/26030/how-to-reach-nrf52840-uarte-current-supply-specification/102605#102605
  //If you are using UARTE1 the base address is 0x40028000
  
  *(volatile uint32_t *)0x40002FFC = 0;
  *(volatile uint32_t *)0x40002FFC;
  *(volatile uint32_t *)0x40002FFC = 1;
  }
  uartInited = false;
  
}

void uc_init()
{
    ret_code_t err_code;
    uc_deInit();
    nrf_libuarte_async_config_t nrf_libuarte_async_config = {
            .tx_pin     = UC_TX_PIN,
            .rx_pin     = UC_RX_PIN,
            .baudrate   = UARTE_BAUDRATE_BAUDRATE_Baud1M,
            .parity     = NRF_UARTE_PARITY_EXCLUDED,
            .hwfc       = NRF_UARTE_HWFC_DISABLED,
            .timeout_us = 100, //86us/byte
            .pullup_rx  = false,//true,
            .int_prio   = APP_IRQ_PRIORITY_HIGH
    };

    err_code = nrf_libuarte_async_init(&libuarte, &nrf_libuarte_async_config, uart_event_handler, (void *)&libuarte);
    uartInited = true;
    APP_ERROR_CHECK(err_code);

    nrf_libuarte_async_enable(&libuarte);
}

 

Everything works before first sleep, when uc_deInit() executed then uc_init(), the NRF stop receiving but transmit works, I can confirm the UC received the NRF tx packet and response, but uart_event_handler never triggered.

So, what is the correct procedure for my purpose?

Thanks.

[Simonr]

Hi

You will need to reinitialize the UARTE driver completely after doing writes to 0x40002FFC. This is because the workaround you're using effectively power cycle the peripheral, so you must configure it again before it can be used.

Best regards,

Simon

[esonhon]

Thanks, Simon,

Do you mean I must redefine libuarte that defined by

NRF_LIBUARTE_ASYNC_DEFINE(libuarte, 0, 1, 2, NRF_LIBUARTE_PERIPHERAL_NOT_USED, PACK_MAX_LENGTH, 3); //DO NOT USE TIMER0 WHEN softdevice enabled

If so, how can I redefine it?

[esonhon]

I delete the 3 lines workarounds, but uarte receive still not work after wakeup.

Perhaps it's not the key.

[esonhon]

I just add trace code to uart event handler just few minutes ago, 

        case NRF_LIBUARTE_ASYNC_EVT_ERROR:
            NRF_LOG_WARNING("libuarte general error %d.\n", p_evt->data.errorsrc);
            break;

After wakeup, when uC send data, I got ERRORSRC =0 from log.

It's really confusing.

[esonhon]

Ok, I fixed it finally. Share my solution here, may help someone who have the same situation.

The uart_event_handler is triggered in an INTERRUPT routine, not some kined of MESSAGE like many RTOS do.

I dealed with the last packet then uninit the libuarte without return from uart_event_handler. I think some internal state must be halted. So, it's my falt.

After dealed with the last RX packet, take a variable mark and return from the event handler soon, then unit the libuarte in the main loop. 

It solved my problem.