How can I implement UART RX PPI with GPIO?

[William_dev]

Hi, I use nRF52840, with SDK 15.3.0

I would like to toggle LED every time receive 1 byte to UART.

So I wrote down the code.

static void ppi_init()
{
uint32_t err_code;

uint32_t uart_event_addr;
uint32_t gpio_task_addr;

nrf_ppi_channel_t ppi_channel_uart_gpio_toggle;

err_code = nrf_drv_ppi_init();
if((err_code != 0) && (err_code != NRF_ERROR_MODULE_ALREADY_INITIALIZED))
{
APP_ERROR_CHECK(err_code);
}

nrf_drv_gpiote_out_config_t config = GPIOTE_CONFIG_OUT_TASK_TOGGLE(false);

err_code = nrf_drv_gpiote_out_init(LED_pin, &config);
APP_ERROR_CHECK(err_code);

err_code = nrf_drv_ppi_channel_alloc(&ppi_channel_uart_gpio_toggle);
APP_ERROR_CHECK(err_code);

uart_event_addr = nrfx_uart_event_address_get(&uart1_inst, NRF_UART_TASK_STARTRX);
gpio_task_addr = nrfx_gpiote_out_task_addr_get(LED_pin);

err_code = nrfx_ppi_channel_assign(ppi_channel_uart_gpio_toggle, uart_event_addr, gpio_task_addr);
APP_ERROR_CHECK(err_code);

err_code = nrf_drv_ppi_channel_enable(ppi_channel_uart_gpio_toggle);
APP_ERROR_CHECK(err_code);

nrf_drv_gpiote_out_task_enable(LED_pin);

}

Thanks in advance!

[Vidar Berg]

Hello,

You are retrieving the task address here:

uart_event_addr = nrfx_uart_event_address_get(&uart1_inst, NRF_UART_TASK_STARTRX);

while it should have been

uart_event_addr = nrfx_uart_event_address_get(&uart1_inst, NRF_UART_EVENT_RXDRDY);

Hope this helps.

Best regards,

Vidar

.

[William_dev]

Hi, I appreciate to your reply.

Let me go back to second question.

I tried UARTE but It cause matter to system that I designed.

As, is there any answer use UART peripheral?

The matter is when I receive one byte, just LED toggle once. And receive next one byte, there's no response to LED.

Plz check the code below.

void ppi_init()
{
            uint32_t err_code;

            uint32_t uart_event_addr;
            uint32_t gpio_task_addr;
            
            nrf_ppi_channel_t ppi_channel_uart_gpio_toggle;
    
            err_code = nrf_drv_ppi_init();
            if((err_code != 0) && (err_code != NRF_ERROR_MODULE_ALREADY_INITIALIZED))
            {
                APP_ERROR_CHECK(err_code);
            }
    
            nrf_drv_gpiote_out_config_t config = GPIOTE_CONFIG_OUT_TASK_TOGGLE(0);
    
            err_code = nrf_drv_gpiote_out_init(LED_1, &config);
            APP_ERROR_CHECK(err_code);
    
            err_code = nrf_drv_ppi_channel_alloc(&ppi_channel_uart_gpio_toggle);
            APP_ERROR_CHECK(err_code);
    
            uart_event_addr = nrfx_uart_event_address_get(&uart1_inst, NRF_UART_EVENT_RXDRDY);
            gpio_task_addr = nrfx_gpiote_out_task_addr_get(LED_1);
            
            err_code = nrfx_ppi_channel_assign(ppi_channel_uart_gpio_toggle, uart_event_addr, gpio_task_addr);
            APP_ERROR_CHECK(err_code);
    
            err_code = nrf_drv_ppi_channel_enable(ppi_channel_uart_gpio_toggle);
            APP_ERROR_CHECK(err_code);
    
            nrfx_gpiote_out_task_enable(LED_1);
}

Best regards,

William.