#include <stddef.h> #include <avr/interrupt.h> #include <avr/io.h> #include "uart.h" #define UBRR_VAL ((F_CPU+BAUD*8)/(BAUD*16)-1) #define BAUD_REAL (F_CPU/(16*(UBRR_VAL+1))) #define BAUD_ERROR ((BAUD_REAL*1000)/BAUD) #if ((BAUD_ERROR<990) || (BAUD_ERROR>1010)) #error Choose another crystal. Baud error too high. #endif static void (*recv_handler)(unsigned char c) = NULL; ISR(USART_RX_vect) { cli(); if(recv_handler) recv_handler(UDR); sei(); } void uart_init() { // Enable receive and transmit UCSRB = (1<<RXEN)|(1<<TXEN)|(1<<RXCIE); // Asynchronous mode, 8N1 UCSRC = (1<<UCSZ1)|(1<<UCSZ0); UBRRH = UBRR_VAL >> 8; UBRRL = UBRR_VAL & 0xFF; } void uart_set_recv_handler(void (*handler)(unsigned char c)) { recv_handler = handler; } void uart_putc(const char c) { while ( !(UCSRA & (1<<UDRE)) ); UDR = (const unsigned char)c; } void uart_puts(const char* str) { do { uart_putc(*str); } while(*++str); }