Tooltron

/********

 * This file is part of Tooltron.

 *

 * Tooltron is free software: you can redistribute it and/or modify

 * it under the terms of the Lesser GNU General Public License as published by

 * the Free Software Foundation, either version 3 of the License, or

 * (at your option) any later version.

 *

 * Tooltron 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

 * Lesser GNU General Public License for more details.

 * You should have received a copy of the Lesser GNU General Public License

 * along with Tooltron.  If not, see <http://www.gnu.org/licenses/>.

 *

 * Copyright 2009 Kevin Woo <kwoo@2ndt.com>

 *

 ********/

/** @file uart.c

 *        

 *        @brief Implements UART functionality in hardware

 *

 *        @author Kevin Woo (kwoo)

 */

#include "uart.h"

#include <avr/delay.h>

#include <stdint.h>

uint8_t received_byte;     //Byte received

uint8_t byte_ready;        //New byte has been received

void init_uart(uint16_t baud) {

        // Set baud rate

        UBRRH = (uint8_t)(baud>>8);

        UBRRL = (uint8_t)baud;

        // Enable RX/TX and RX/TX Interrupt

        UCSRB = _BV(RXCIE) | _BV(RXEN) | _BV(TXCIE) | _BV(TXEN);

        // Enable the TXEN pin as output

        DDRD |= TX_EN;

    // Initialize receive variables

    byte_ready = 0;

    received_byte = 0x0;

}

int8_t uart_get_byte(uint8_t *output_byte) {

        if (byte_ready) {

                byte_ready = 0;

                *output_byte = received_byte;

                return 0;

        } else {

                return -1;

        }

}

void uart_send_byte(uint8_t data) {

        //Waits until current transmit is done

    while (!(UCSRA & _BV(UDRE)));

    // Enable writes and send

        uart_toggle_transmit(UART_TX_ON);

    UDR = data;

        return;

}

char usb_puti(int value ) {

  unsigned char usb_data[6]={'0','0','0','0','0','0' }, position=sizeof(usb_data), radix=10; 

  /* convert int to ascii  */ 

  if(value<0) { 

    uart_send_byte('-'); 

    value=-value; 

  }    

  do { 

    position--; 

    *(usb_data+position)=(value%radix)+'0'; 

    value/=radix;  

  } while(value); 

  /* start displaying the number */

  for(;position<=(sizeof(usb_data)-1);position++) {

    uart_send_byte(usb_data[position]);

  }

  return 0;

}

void uart_toggle_transmit(uint8_t state) {

        if (state == UART_TX_ON) {

                PORTD |= TX_EN;

        } else {

                PORTD &= ~TX_EN;

        }

}

ISR(USART_RX_vect) {

    received_byte = UDR;

    byte_ready = 1;    

}

ISR(USART_TX_vect) {

    // Re-enable reads

    uart_toggle_transmit(UART_TX_OFF);

}