avr-lcd-lib/USART.c

/**
 * (C) Copyright Collin J. Doering 2015
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

/**
 * File: USART.c
 * Author: Collin J. Doering <collin.doering@rekahsoft.ca>
 * Date: Oct  6, 2015
 */

#include <avr/io.h>
#include "USART.h"
#include <util/setbaud.h>

#ifndef BAUD                          /* if not defined in Makefile... */
#define BAUD  9600                     /* set a safe default baud rate */
#endif

void initUSART(void) {                                /* requires BAUD */
  UBRR0H = UBRRH_VALUE;                        /* defined in setbaud.h */
  UBRR0L = UBRRL_VALUE;
#if USE_2X
  UCSR0A |= (1 << U2X0);
#else
  UCSR0A &= ~(1 << U2X0);
#endif
                                  /* Enable USART transmitter/receiver */
  UCSR0B = (1 << TXEN0) | (1 << RXEN0);
  UCSR0C = (1 << UCSZ01) | (1 << UCSZ00);   /* 8 data bits, 1 stop bit */
}


void transmitByte(uint8_t data) {
                                     /* Wait for empty transmit buffer */
  loop_until_bit_is_set(UCSR0A, UDRE0);
  UDR0 = data;                                            /* send data */
}

void transmitString(const char* data) {
  while (*data != '\0') {
    transmitByte(*data);
    data++;
  }
}

uint8_t receiveByte(void) {
  loop_until_bit_is_set(UCSR0A, RXC0);       /* Wait for incoming data */
  return UDR0;                                /* return register value */
}