Shutting down UARTE cleanly, stuck at NRF_UARTE_EVENT_TXSTOPPED

RE: Shutting down UARTE cleanly, stuck at NRF_UARTE_EVENT_TXSTOPPED

RobMeades — Mon, 06 Apr 2020 12:14:15 GMT

Right, I have it working now. There were two problems:

1. It helps if you enable the UARTE :-). I had nrf_uarte_int_enable() but didn't also have nrf_uarte_enable(). However, that alone didn't fix it...

2. My Tx is always blocking, so I handle TX_STOP etc. in my send routine. But I'd also OR'ed the Tx events into the interrupt enable. I had to take the Tx events out of the bitmask given to nrf_uarte_int_enable() then everything behaves.

Phew, at last. Thanks for trying to help me with this.

RE: Shutting down UARTE cleanly, stuck at NRF_UARTE_EVENT_TXSTOPPED

RobMeades — Fri, 03 Apr 2020 14:42:36 GMT

Well, replacing what I have in main_test.c with what's in that example's main.c certainly works in that it doesn't get stuck on NRF_UARTE0->EVENTS_TXSTOPPED, it flows through and ends up in the while() loop at the end. So what am I doing wrong?

RE: Shutting down UARTE cleanly, stuck at NRF_UARTE_EVENT_TXSTOPPED

Simon — Thu, 02 Apr 2020 20:57:49 GMT

I am currently looking into it. I attached a logic analyzer to look at the TX pin, and I noticed that nothing was being sent at all.

I also saw that the event EVENTS_TXSTARTED did not happen either, thus the call to nrf_uarte_task_trigger(.. NRF_UARTE_STARTTX) has no effect.

I will investigate more tomorrow.

However, here is a nice bare-metal example that demonstrates, on a register level, how to configure UARTE and transmit a message. It might be nice to use it as a reference. Just copy the content of main.c into your projects main.c

Best regards,

Simon

RE: Shutting down UARTE cleanly, stuck at NRF_UARTE_EVENT_TXSTOPPED

RobMeades — Thu, 02 Apr 2020 19:58:22 GMT

Any insights?

RE: Shutting down UARTE cleanly, stuck at NRF_UARTE_EVENT_TXSTOPPED

RobMeades — Tue, 31 Mar 2020 23:05:00 GMT

Thanks: I'm sure it is something stupid that I've [not] done, appreciate your help.

Rob

RE: Shutting down UARTE cleanly, stuck at NRF_UARTE_EVENT_TXSTOPPED

Simon — Tue, 31 Mar 2020 21:45:08 GMT

Strange... I will take a look at it tomorrow.

Best regards,

Simon

RE: Shutting down UARTE cleanly, stuck at NRF_UARTE_EVENT_TXSTOPPED

RobMeades — Tue, 31 Mar 2020 11:15:12 GMT

I've update the post above to include a ZIP file that contains a standalone build, a single source file, showing what I'm doing. If you run it in the debugger you can see that I initialise UARTE0 and then attempt to transmit a few bytes through it. The code stops at the line where I'm waiting for NRF_UARTE_EVENT_TXSTOPPED.

I must be doing something really basic wrong: can you see what?

RE: Shutting down UARTE cleanly, stuck at NRF_UARTE_EVENT_TXSTOPPED

RobMeades — Mon, 30 Mar 2020 08:53:40 GMT

Interesting changes but I'm not sure they have helped in my case. As you will see from the code above, I have a buffer within my driver code which is set up to receive constantly (gUartData[uart].rxBuffer.pBufferStart) from the point that my init() function is called, so there is always reception on-going. Hence the code at your link:

    if (p_cb->handler)
    {
        interrupts_disable(p_instance);
    }
    // Make sure all transfers are finished before UARTE is disabled
    // to achieve the lowest power consumption.
    nrf_uarte_shorts_disable(p_reg, NRF_UARTE_SHORT_ENDRX_STARTRX);

    // Check if there is any ongoing reception.
    if (p_cb->rx_buffer_length)
    {
        nrf_uarte_event_clear(p_reg, NRF_UARTE_EVENT_RXTO);
        nrf_uarte_task_trigger(p_reg, NRF_UARTE_TASK_STOPRX);
    }

    nrf_uarte_event_clear(p_reg, NRF_UARTE_EVENT_TXSTOPPED);
    nrf_uarte_task_trigger(p_reg, NRF_UARTE_TASK_STOPTX);

    // Wait for TXSTOPPED event and for RXTO event, provided that there was ongoing reception.
    while (!nrf_uarte_event_check(p_reg, NRF_UARTE_EVENT_TXSTOPPED) ||
           (p_cb->rx_buffer_length && !nrf_uarte_event_check(p_reg, NRF_UARTE_EVENT_RXTO)))
    {}

    nrf_uarte_disable(p_reg);

...reduces to:

    nrf_uarte_int_disable(pReg, NRF_UARTE_INT_ENDRX_MASK |
                                NRF_UARTE_INT_ENDTX_MASK |
                                NRF_UARTE_INT_ERROR_MASK |
                                NRF_UARTE_INT_RXTO_MASK  |
                                NRF_UARTE_INT_TXSTOPPED_MASK);
    NRFX_IRQ_DISABLE(nrfx_get_irq_number((void *) (pReg)));
    
    // Make sure all transfers are finished before UARTE is
    // disabled to achieve the lowest power consumption
    nrf_uarte_shorts_disable(pReg, NRF_UARTE_SHORT_ENDRX_STARTRX);
    nrf_uarte_event_clear(pReg, NRF_UARTE_EVENT_RXTO);
    nrf_uarte_task_trigger(pReg, NRF_UARTE_TASK_STOPRX);
    nrf_uarte_event_clear(pReg, NRF_UARTE_EVENT_TXSTOPPED);
    nrf_uarte_task_trigger(pReg, NRF_UARTE_TASK_STOPTX);
    while (!nrf_uarte_event_check(pReg, NRF_UARTE_EVENT_TXSTOPPED) ||
           !nrf_uarte_event_check(pReg, NRF_UARTE_EVENT_RXTO)) {}
    
    // Disable the UARTE
    nrf_uarte_disable(pReg);

...which still gets stuck for me at that while() statement.

So that you can see the full picture, my entire driver (without these latest changes above) is visible here:

https://github.com/u-blox/cellular/blob/master/port/platform/nordic/nrf52840/src/cellular_port_uart.c

Can you see anything else that I'm doing wrong, or have I somehow misunderstood the intention of the changes?

RE: Shutting down UARTE cleanly, stuck at NRF_UARTE_EVENT_TXSTOPPED

Simon — Sun, 29 Mar 2020 21:01:32 GMT

Some changes were recently made to the NRFX drivers which I think will fix your problem: https://github.com/NordicSemiconductor/nrfx/blob/master/CHANGELOG.md

"Improved the UARTE driver to consume less current after the driver uninitialization. Now all clocks are disabled properly after uninitialization."

Check it out here

Best regards,

Simon