/*************************************************************************** * Atmel AVR USART Library for GCC * Version: 1.0 *  * Works with AVR MCUs equiped with USART hardware (ATmega series).  * Does not work with older UART's or USI of ATtiny series. * Tested with ATmega8. * * Uses USART Receive Complete Interrupt. Disabling Global Interrupts * after usart initialization disables data receive. * * Jaakko Ala-Paavola 2003/06/28 * http://www.iki.fi/jap email:jap@iki.fi */// Size of receive ring buffer. Must be at least 2.#define USART_BUFFER_SIZE 10/* Baudrate settings. Refer to datasheet for baud rate error.   Note also maximun baud rate.   br = baudrate, fosc = clock frequency in megahertzs */#define USART_BAUDRATE(br, fosc) (fosc*125000/br-1)/* Initializes USART device. Use USART_BAUDRATE macro for argument or   consult datasheet for correct value. */void usart_init(unsigned char baud_divider);/* Transmit one character. No buffering, waits until previous character   transmitted. */void usart_putc(char a);/* Transmit string. Returns after whole string transmitted. */void usart_puts(char *data);/* Receive one character. Blocking operation, if no new data in buffer. */char usart_getc(void);/* Returns number of unread character in ring buffer. */unsigned char usart_unread_data(void);