Reconfig UART RX PIN as GPIO and use it to wake-up 52840. And how to do it using Zephyr UART?

RE: Reconfig UART RX PIN as GPIO and use it to wake-up 52840. And how to do it using Zephyr UART?

Simonr — Mon, 13 Sep 2021 06:01:01 GMT

Hi Anthony

Indeed, the development will be somewhat different on NCS than in the nRF5 SDK. The equivalent of app_uart_close() in NCS would be the nrfx_uart_uninit function which uninitializes and closes the UART driver.

Best regards,

Simon

RE: Reconfig UART RX PIN as GPIO and use it to wake-up 52840. And how to do it using Zephyr UART?

Anthony Yuan — Fri, 10 Sep 2021 04:09:45 GMT

Thanks for the update Simon.

I read lpuart sample code and it looks like a sample shows how to use 4-wire lpuart but I can not find how it handles rdy-pin.

I came across this repo NordicPlayground/nrf51-UART-examples and it use below code to set UART off when CTS pin toggled.

uint32_t app_uart_close(uint16_t app_uart_uid)
{
    uint16_t gpiote_uid;

    if (app_uart_uid < UART_INSTANCE_GPIOTE_BASE)
    {
        on_uart_event(ON_UART_CLOSE);
        return NRF_SUCCESS;
    }

    gpiote_uid = (app_uart_uid >> 8) & UART_INSTANCE_GPIOTE_BASE;

    if (gpiote_uid != m_gpiote_uid)
    {
        return NRF_ERROR_INVALID_PARAM;
    }

    on_uart_event(ON_UART_CLOSE);

    return app_gpiote_user_disable(m_gpiote_uid);
}

/**@brief Function for disabling the UART when entering the UART_OFF state.
 */
static void action_uart_deactivate(void)
{
    m_current_state         = UART_OFF;
    NRF_UART0->TASKS_STOPTX = 1;
    NRF_UART0->TASKS_STOPRX = 1;
    NRF_UART0->ENABLE       = (UART_ENABLE_ENABLE_Disabled << UART_ENABLE_ENABLE_Pos);
}

But I can not find code handle NRF_UART0 register in NCS1.6.1, seems deprecated?

Could you let me know which function is the counterpart of app_uart_close() in NCS?

Regards,

Anthony

RE: Reconfig UART RX PIN as GPIO and use it to wake-up 52840. And how to do it using Zephyr UART?

Simonr — Thu, 09 Sep 2021 10:27:19 GMT

Hi The lpuart source code can be found in \NCS_FOLDER\v1.x.0\nrf\samples\peripheral\lpuart.

Best regards,

Simon

RE: Reconfig UART RX PIN as GPIO and use it to wake-up 52840. And how to do it using Zephyr UART?

Anthony Yuan — Wed, 08 Sep 2021 03:22:05 GMT

Hi Simon,

I came across this thread during my search: can-the-lpuart-be-used-without-the-2-additional-control-lines

I think I can not take the advantage of lpuart directly, as config the rdy-pin to use the same GPIO as the rx-pin will not work.

Can I find the source code of how rdy-pin/IRQ is handled by nrf-sw-lpuart? Maybe I can use it as an example to modified my own 2-wire UART application which using IRQ of rx-pin to enable UART receiver.

Regards,

Anthony

RE: Reconfig UART RX PIN as GPIO and use it to wake-up 52840. And how to do it using Zephyr UART?

Simonr — Tue, 07 Sep 2021 13:24:52 GMT

Hi Anthony

Have you checked out the low power UART driver in NCS? It does exactly what you're describing here in terms of enabling the RX channel before setting up the receiver and go to sleep (low power state).

Best regards,

Simon