Once the Software Framework drivers are selected, replace your main.c with main.c (USART)

Let’s take a close look to the code:

First of all we will include the header files from the framework that we will use, this includes the AVR32 IO definition, GPIO, USART and Power Manager.

// Include Files
#include <avr32/io.h>
// EVK1101
#include "board.h"
// Drivers
#include "power_clocks_lib.h"
#include "gpio.h"
#include "usart.h"

then we will define the frequency for the PBA, which USART we will use, and which GPIO pins we will be connected to that UART

#define TARGET_PBACLK_FREQ_HZ FOSC0  // PBA clock target frequency, in Hz
// Usart Pins compatible with EVK1101
#define MY_USART               (&AVR32_USART1)
#define MY_USART_RX_PIN        AVR32_USART1_RXD_0_0_PIN
#define MY_USART_RX_FUNCTION   AVR32_USART1_RXD_0_0_FUNCTION
#define MY_USART_TX_PIN        AVR32_USART1_TXD_0_0_PIN
#define MY_USART_TX_FUNCTION   AVR32_USART1_TXD_0_0_FUNCTION
#define MY_USART_CLOCK_MASK    AVR32_USART1_CLK_PBA
#define MY_PDCA_CLOCK_HSB      AVR32_PDCA_CLK_HSB
#define MY_PDCA_CLOCK_PB       AVR32_PDCA_CLK_PBA

in the main function we will configure the GPIO pins. this is done by creating a variable of type gpio_map_t which includes the pin and its function.

	static const gpio_map_t MY_USART_GPIO_MAP = {
			{MY_USART_RX_PIN, MY_USART_RX_FUNCTION},
			{MY_USART_TX_PIN, MY_USART_TX_FUNCTION} };

then we set up the UART parameters, this includes the baudrate, parity and stop among others.

	static const usart_options_t MY_USART_OPTIONS = { .baudrate= 57600, .charlength= 8,
			.paritytype= USART_NO_PARITY, .stopbits = USART_1_STOPBIT,
			.channelmode = USART_NORMAL_CHMODE };

next we configure the Power Clock in order to use the crystal connected to OSC0.

	pcl_switch_to_osc(PCL_OSC0, FOSC0, OSC0_STARTUP);

We need to tell the GPIO module that it must assign the GPIO pins to the USART

	gpio_enable_module(MY_USART_GPIO_MAP,sizeof(MY_USART_GPIO_MAP)/sizeof(MY_USART_GPIO_MAP[0]));

For enabling the UART the framework provides a function for initializing in RS232 mode

	usart_init_rs232(MY_USART,&MY_USART_OPTIONS,TARGET_PBACLK_FREQ_HZ);

And last, but not least, you can see in this few lines of code how to write and read from the UART

	usart_write_line(MY_USART, "This is an echo program)n");
	while(1) {
		c = usart_getchar(MY_USART);
		usart_putchar(MY_USART,c);
	}