uart1.c

avr usart sample (interrupt)

#include <avr/io.h>
#include <avr/interrupt.h>
#include <avr/sleep.h>
#include <string.h>

#define UART_BAUD_RATE 19200
#define UART_BAUD_SELECT (((((F_CPU+(UART_BAUD_RATE/2))/UART_BAUD_RATE)+8)/16)-1)

#ifdef _AVR_IOTN2313_H_
#define UART_TX_vect USART_TX_vect
#define UART_RX_vect USART_RX_vect
#define UCR UCSRB
#define UBRR UBRRL
#endif //attiny2313

static volatile uint8_t *uart_data_ptr;
static volatile uint8_t uart_counter;
static volatile uint8_t led;
static volatile uint8_t flag;
static volatile uint8_t txReady;

ISR(UART_TX_vect)
{
	uart_data_ptr++;

	if(--uart_counter && txReady) {
		UDR = *uart_data_ptr;
		txReady = 0;
	}
}

ISR(UART_RX_vect)
{
	led = UDR;
	PORTB = ~led;
	flag = 1;
}

ISR(USART_UDRE_vect)
{
	txReady = 1;
}


void uart_send(uint8_t* buff, uint8_t size)
{
	if(!uart_counter) {
		uart_data_ptr = buff;
		uart_counter = size;
		UDR = *buff;
	}
}


void uart_init(void)
{
	UCR = _BV(RXCIE) | _BV(TXCIE) | _BV(RXEN) | _BV(TXEN);
#ifdef _AVR_IOTN2313_H_
	UBRRH = (uint8_t)(UART_BAUD_SELECT >> 8);
	UCSRC = _BV(USBS) | _BV(UCSZ0);
#endif //attiny2313
	UBRR = (uint8_t)UART_BAUD_SELECT;
}

char* int2str(uint8_t num, char* str_val)
{
	uint8_t i;
	uint8_t hi = num >> 4;
	str_val[0] = '0';
	str_val[1] = 'x';
	str_val[4] = 0;
	for(i=2; i<4; i++) {
		if(hi > 9) str_val[i] = hi + 55;
		else str_val[i] = hi + 48;
		hi = num & 0x0f;
	}
	return str_val;
}

		

int main(void)
{
	cli();
	char str_val[5];
	char message[21] = "Recive value:";

	uart_init();

	DDRB = 0xff;
	PORTB = 0x00;

	flag = 0;
	txReady = 1;
	uart_counter = 0;
	
	sei();

	while(1) {
		if(flag == 1) {	
			strcpy(message, "Recive value:");
			int2str(led, str_val);
			strcat(message, str_val);
			strcat(message, "###");
			uart_send(message, sizeof(message)-1);

			flag = 0;
		}
		sleep_enable();
		sleep_cpu();
		sleep_disable();
	}
    return(0);
}