How to configure and use a UART in a polled fashion.

File(s):

arch/avr/tutorials/04_uart/uart.c

The UART is configured to 115200 BAUD, 8 Data Bits, No Parity and 1 Stop Bit. The string "UART\r\n" is sent upon start up. Thereafter all received characters are echoed back to the sender.

The clock rate of the AVR is defined in "px_board.h" with the macro F_CPU. It is a good programming practice to precalculate values at compile time, instead of using "magic values". For example, the value to use for the UBBR register is calculated with the following macro:

#define UART0_UBBR_VAL ((F_CPU / (UART0_BAUD * 16)) - 1)

instead of using a hard coded value:

#define UART0_UBBR_VAL 3 // Magic Value for 115200 Baud at a clock rate of 7.3728 MHz