uart pin connfiguration

[Vojislav]

Hi, 

I am using nrf52840 DK to create the uart ble app. The starting point is ble_app_uart example from SDK52 15.3. I changed pin configuration for uart so I can have RX and TX pins on one of the external headers. This is the code in the pca10052.h file (in the comment is the previous value):

#define RX_PIN_NUMBER  12//8
#define TX_PIN_NUMBER  11//6
#define CTS_PIN_NUMBER NRF_GPIO_PIN_MAP(1,8)//7
#define RTS_PIN_NUMBER 7//5
#define HWFC           false//true

One thing I notice is that the application will brake on uart_init when rx and tx pins are not connected to uart dongle. Is there a way to overcome this issue with some software or hardware configuration?

[Edvin]

It is probably the UART event handler receiving some communication error. Try to comment out the APP_ERROR_HANDLER() in the uart communication error event, and see if that changes the behavior. 

The issue is that the UART's RX line is floating, and when the pin floats between 1 and 0 the UART believe that someone has tried to send a message, but it was corrupted.

Best regards,

Edvin

[Vojislav]

Commenting out APP_ERROR_HANFLER() worked, thank you.

Is this safe for code, or should this state be handled somehow?  

[Edvin]

The APP_ERROR_HANDLER() or the APP_ERROR_CHECK is good for use during development, or if you want to reset the device when an error occurs. In some cases, you may not care about certain events/return values. In that case it is safe to remove them.

Just know that in this case, you will not get an event when you actually have some communication error, but I don't think that is a common issue when the pins are connected.