UART HW FLOW Control testing

[Justin_Yeh]

Hi Sir 

I enabled the "APP_UART_FLOW_CONTROL_ENABLED", but I measured the CTS / RTS pin always is low during data transmission. 

Is it normal ? How to check UART FLOW control is working or not ?

---------------------------------------------------------------------------

rmx_error uart_init(void)
{
uint32_t err_code;

const app_uart_comm_params_t comm_params =
{
UART_RX_PIN,
UART_TX_PIN,
UART_RTS_PIN,
UART_CTS_PIN,
APP_UART_FLOW_CONTROL_ENABLED, 
false,
#if defined (UART_PRESENT)
NRF_UART_BAUDRATE_115200
#else
NRF_UARTE_BAUDRATE_115200
#endif
};

APP_UART_FIFO_INIT(&comm_params,
UART_RX_BUF_SIZE,
UART_TX_BUF_SIZE,
uart_error_handle,
APP_IRQ_PRIORITY_LOWEST,
err_code
);

APP_ERROR_CHECK(err_code);

}

[Simonr]

Hi

The UART flow control by default is active low on both these pins, which is why they are low during data transmission, so this is totally normal.

You should be able to control these lines fully in software. For example, you can based on the logic levels on the pins, start and stop the UART to receive or transmit serial data. 

Best regards,

Simon

[Justin_Yeh]

But, even uart data transmission complete, the CTS/RTS still keep low, Is it normal ? 

Nordic uart library doesn't control these pins ? because CTS/RTS always keep low.