nRF52832 UART problem

Question

Hello,

I've been trying to write my own library that uses UART.

I went through the "uart" example and wrote this piece of code.

uart.c

void uart_set_baudrate(uint32_t val)
{
    NRF_UART0->BAUDRATE = val;
}

void uart_configure(uint32_t parity, uint32_t hwfc)
{
    NRF_UART0->CONFIG = (parity << UART_CONFIG_PARITY_Pos) | (hwfc << UART_CONFIG_HWFC_Pos);
}

void uart_set_pins(uint32_t txpin, uint32_t rxpin)
{
    NRF_UART0->PSELRXD = rxpin;
    NRF_UART0->PSELTXD = txpin;
}

void uart_enable(void)
{
    NRF_UART0->ENABLE = UART_ENABLE_ENABLE_Enabled;
}

void uart_init(void)
{
    uart_set_baudrate(UART_BAUDRATE_BAUDRATE_Baud115200);
    uart_configure(UART_CONFIG_PARITY_Excluded, UART_CONFIG_HWFC_Disabled);
    uart_set_pins(6, 8);

    uart_enable();
}

void uart_write(uint8_t data)
{
    NRF_UART0->TXD = data;
}

gpio.c

void gpio_out_set(uint32_t pin_num)
{
    NRF_GPIO_Type * reg = NRF_P0;
    reg->OUTSET = (1 << pin_num);
}

void gpio_config_input(uint32_t pin_num, uint32_t pull)
{
    NRF_GPIO_Type * reg = NRF_P0;
    reg->PIN_CNF[pin_num] = ((uint32_t)GPIO_PIN_CNF_DIR_Input << GPIO_PIN_CNF_DIR_Pos)
                               | ((uint32_t)GPIO_PIN_CNF_INPUT_Connect << GPIO_PIN_CNF_INPUT_Pos)
                               | ((uint32_t)pull << GPIO_PIN_CNF_PULL_Pos)
                               | ((uint32_t)GPIO_PIN_CNF_DRIVE_S0S1 << GPIO_PIN_CNF_DRIVE_Pos)
                               | ((uint32_t)GPIO_PIN_CNF_SENSE_Disabled << GPIO_PIN_CNF_SENSE_Pos);     // input sense options
}

void gpio_config_output(uint32_t pin_num)
{
    NRF_GPIO_Type * reg = NRF_P0;
    reg->PIN_CNF[pin_num] = ((uint32_t)GPIO_PIN_CNF_DIR_Output << GPIO_PIN_CNF_DIR_Pos)
                                | ((uint32_t)GPIO_PIN_CNF_INPUT_Disconnect << GPIO_PIN_CNF_INPUT_Pos)
                                | ((uint32_t)GPIO_PIN_CNF_PULL_Disabled << GPIO_PIN_CNF_PULL_Pos)
                                | ((uint32_t)GPIO_PIN_CNF_DRIVE_S0S1 << GPIO_PIN_CNF_DRIVE_Pos)
                                | ((uint32_t)GPIO_PIN_CNF_SENSE_Disabled << GPIO_PIN_CNF_SENSE_Pos);
}

main.c

    gpio_out_set(6);
    gpio_config_output(6);

    gpio_config_input(8, GPIO_PIN_CNF_PULL_Disabled);
    
    uart_init();

    while(true)
    {
        //send_packet_blocking();
        nrf_delay_ms(100);
        uart_write('A');
    }

I modified the example to work without DMA and I get the same values in the registers of the UART (except for the interrupts) and the GPIO.

I exported the registers after the initialization and my code setups the registers exactly the same as the example "uart"

But I don't get anything in the serial port.

Any advice?

George555 · Answer

I found the mistake. 
 I should have start the transceiver with 
 NRF_UART0->TASKS_STARTTX = 1; 
 
 Also, why do I have to access the events with pointer dereference? 
 while(*(uint32_t*)NRF_UART0->EVENTS_TXDRDY == 0);