AVR Freaks

This code consists of twi, usart and gpio. For AT32UC3B0512.

/**
 * \file
 *
 * \brief Empty user application template
 *
 */

/**
 * \mainpage User Application template doxygen documentation
 *
 * \par Empty user application template
 *
 * Bare minimum empty user application template
 *
 * \par Content
 *
 * -# Include the ASF header files (through asf.h)
 * -# "Insert system clock initialization code here" comment
 * -# Minimal main function that starts with a call to board_init()
 * -# "Insert application code here" comment
 *
 */

/*
 * Include header files for all drivers that have been imported from
 * Atmel Software Framework (ASF).
 */
/*
 * Support and FAQ: visit <a href="http://www.atmel.com/design-support/">Atmel Support</a>
 */
#include <avr32/io.h>
#include <asf.h>

#define USART_SERIAL                     &AVR32_USART0
#define USART_SERIAL_BAUDRATE            9600
#define USART_SERIAL_CHAR_LENGTH         8
#define USART_SERIAL_PARITY              USART_NO_PARITY
#define USART_SERIAL_STOP_BIT            USART_1_STOPBIT

void twi_init(void)
{
	twi_master_options_t opt = {
		.speed = 50000,
		.chip  = 0x68
	};
	
	static const gpio_map_t twi_gpio = {
		{9,0},
		{10,0}
	};
	
	gpio_enable_module(twi_gpio, sizeof(twi_gpio) / sizeof(twi_gpio[0]));

	twi_master_setup(&AVR32_TWI, &opt);
}

void RS232_init(void)
{
	static usart_serial_options_t usart_options = {
		.baudrate = USART_SERIAL_BAUDRATE,
		.charlength = USART_SERIAL_CHAR_LENGTH,
		.paritytype = USART_SERIAL_PARITY,
		.stopbits = USART_SERIAL_STOP_BIT
	};
	
	static const gpio_map_t rs232_gpio = {
		{18,0},
		{19,0}
	};
	
	gpio_enable_module(rs232_gpio,sizeof(rs232_gpio) / sizeof(rs232_gpio[0]));
	
	usart_serial_init(USART_SERIAL, &usart_options);
}


int main (void)
{
	/* Insert system clock initialization code here (sysclk_init()). */

	sysclk_init();
	board_init();
	twi_init();
	RS232_init();
	
	uint8_t data_received[10];

	twi_package_t packet_read = {
		.addr         = 0x75,      // TWI slave memory address data
		.addr_length  = sizeof (uint16_t),    // TWI slave memory address data size
		.chip         = 0x68,      // TWI slave bus address
		.buffer       = data_received,        // transfer data destination buffer
		.length       = 10                    // transfer data size (bytes)
	};
	
	//Enter loop
	while(1)
	{
		// Perform a multi-byte read access then check the result.
		if(twi_master_read(&AVR32_TWI, &packet_read) == TWI_SUCCESS){
		
			usart_serial_write_packet(USART_SERIAL, &data_received[0], sizeof(data_received[0]));
		}
	}
	

	/* Insert application code here, after the board has been initialized. */
}

The  I2C slave device I use is MPU6050, according to the register map, 0x75 is 'wh am i' register, so the usart should print '0x68' in PUTTY. However, when I connected the RS232 USB to my computer and open the correct COM port in PUTTY, it seemed to have no output.

Is there any problem with this code? THANKS!