nRF9160 dk UARTE Baremetal Rx Driver - Unknown Byte Size

[PawanNordic]

Hello,

I am trying to have a minimal bare metal based driver for nrf9160 UARTE with an unknown frame size. 

I assume that ENDRX interrupt is triggered when RXD.MAXCNT bytes are received and RXRDY interrupt is triggered when every byte is received. 

Is there an idle line detect mechanism in nrf9160? I plan to have at least two UARTs in my project with Rx capability.

It would be great if I get a minimal driver / steps or register configuration involved.

Thanks,

Pawan 

[Håkon Alseth]

Hi,

 

Is there an idle line detect mechanism in nrf9160? I plan to have at least two UARTs in my project with Rx capability.

Are you thinking about flow control, using CTS/RTS in addition to RXD/TXD? If so, yes, the hardware supports this.

 

Kind regards,

Håkon

[PawanNordic]

Hello Hakon,

No, I'm just using the TXD RXD lines. I would like to have an interrupt when the RXD line goes idle after recieving an unknown number of bytes. Is this possible?

Thanks

Pawan

[Håkon Alseth]

Hi Pawan,

 

PawanNordic said:

No, I'm just using the TXD RXD lines. I would like to have an interrupt when the RXD line goes idle after recieving an unknown number of bytes. Is this possible?

This isn't a feature that the UARTE peripheral has. This must be added by you, if this is a requirement.

 

I would recommend that you look into the uart asynchronous API from zephyr, where you can set a timeout on the RX operation.

 

Kind regards,

Håkon

[PawanNordic]

Thanks Hakon, I will check it out..

Pawan

[PawanNordic]

Hello Hakon,

I am trying to establish UARTE EVENTS_RXDRDY Interrupt handling on a minimal bare metal firmware and I observe that the ISR is hit only once. Maybe the mcu goes to some fault condition thereafter.

My simple code:

void my_Usart2_init(void)
{
    /* GPIO init */
    nrf_gpio_cfg_default(1);
    nrf_gpio_pin_set(1);
    nrf_gpio_cfg_default(0);
    nrf_gpio_pin_set(0);

    NRF_UARTE2->PSEL.TXD = 1;
    NRF_UARTE2->PSEL.RXD = 0;
    NRF_UARTE2->TASKS_STOPTX = 1;
    NRF_UARTE2->TASKS_STOPRX = 1;    

    NRF_UARTE2->BAUDRATE = (uint32_t)UARTE_BAUDRATE_BAUDRATE_Baud115200;

    /*Initialize DMA*/
    NRF_UARTE2->INTENCLR = 0xffffffffUL;
    NRF_UARTE2->INTENSET =
        (UARTE_INTEN_ENDTX_Enabled << UARTE_INTEN_ENDTX_Pos) |
        (UARTE_INTEN_RXDRDY_Enabled << UARTE_INTEN_RXDRDY_Pos) |
        (UARTE_INTEN_ERROR_Enabled << UARTE_INTEN_ERROR_Pos);

    /* APP IRQ */
    Sys_clearFastAppIrq(UARTE2_SPIM1_SPIS1_TWIM1_TWIS1_IRQn);
    Sys_enableFastAppIrq(UARTE2_SPIM1_SPIS1_TWIM1_TWIS1_IRQn,
                         APP_LIB_SYSTEM_IRQ_PRIO_HI,
                         UARTE2_IRQHandler);
    NRF_UARTE2->ENABLE = UARTE_ENABLE_ENABLE_Enabled;

}

volatile uint8_t datahere;
void __attribute__((__interrupt__)) UARTE2_IRQHandler(void)
{
    if(NRF_UARTE2.instance->EVENTS_RXDRDY != 0)
    {   
        NRF_UARTE2.instance->EVENTS_RXDRDY = 0;
        (NRF_UARTE2.instance->RXD.PTR) = (uint32_t)&datahere;
        NRF_UARTE2.instance->TASKS_STARTRX = 1;
    }
}

I need some expert help or a register level simple example on UARTE Rx please.

Thanks,

Pawan