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 rs485_poll.h

 * @brief Implements rs485 using the uart hardware module.

 *

 * This is compiled for the bootloader so this is just a header file

 *

 * @author Kevin Woo (kwoo)

 */

#ifndef _RS485_SW_H

#define _RS485_SW_H

#include <avr/io.h>

#include <avr/interrupt.h>

#include <stdint.h>

#define RS485_TX_OFF 0

#define RS485_TX_ON 1

/** 

 * @brief This is the value to pass into UBRR to set the baudrate.

 *  @note this assumes an 8MHz system clock

 */

#define BAUD9600    51

/** @brief RX Pin for the RS485 */

#define RX                _BV(PORTD0)

/** @brief TX Pin for the RS485 */

#define TX                _BV(PORTD1)

/** @brief TX Enable Pin for the RS485 */

#define TX_EN        _BV(PORTD5)

/**

 * @brief Initializes the uart

 * @param baud The baudrate. Use the definitions in rs485_sw.h

 */

void rs485_init(uint16_t baud);

/**

 * @brief Non-blocking receive

 * 

 * Receives a byte from the UART if one exists. If none exist the function

 * will return an error code immediately. If there is a byte to receive,

 * it will be placed in a passed in pointer and return.

 *

 * @pre The RS485 TXEN line is not enabled

 * @param output_byte Byte to store the received message

 * @return 0 on success, negative if there is nothing to receive

 */

int8_t rs485_get_byte(uint8_t *output_byte);

/**

 * @brief Blocking send

 *

 * Sends the byte in data onto the network. The function will block until

 * the transmit is complete so that the transmit enable line can be toggled

 * safely. It will wait until any current transmission completes before sending

 * and will wait until it completes before returning. The RS485 TX enable line

 * is automatically toggled by the function and should not be done so

 * outside the function.

 *

 * @param data The byte to send

 */

void rs485_send_byte(uint8_t data);

#endif