I assume you are using the app UART library. You can reset (flush) the UART FIFO RX buffer by calling app_uart_flush(). However, this will flush both the RX and the TX buffer. I couldn't find any functions that did this on the highest abstraction layer (app_uart.h). If you want only to clear the RX buffer you have to modify the files app_uart_fifo.c and app_uart.h (create a function that only runs app_fifo_flush(&m_rx_fifo);)
I assume you are using the app UART library. You can reset (flush) the UART FIFO RX buffer by calling app_uart_flush(). However, this will flush both the RX and the TX buffer. I couldn't find any functions that did this on the highest abstraction layer (app_uart.h). If you want only to clear the RX buffer you have to modify the files app_uart_fifo.c and app_uart.h (create a function that only runs app_fifo_flush(&m_rx_fifo);)
