File content as of revision 0:e076052bcffd:

/*
 ******************************************************************************
 * @file    ManchesterUART.h
 * @author  Zoltan Hudak
 * @version
 * @date    2017-Nov-22
 * @brief   Manchester code over UART for mbed
 ******************************************************************************
 * @attention
 *
 * <h2><center>&copy; COPYRIGHT(c) 2017 Zoltan Hudak <hudakz@outlook.com>
 *
 * All rights reserved.

 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/>.
 */
/*
 * This library implements Manchester code using UART serial connection. Each 
 * data byte is encoded into two bytes representing two nibbles of the original
 * data byte. These two bytes are then sent over UART serial link connection. 
 * The receiver reconstructs the original data byte from the two bytes received.
 * A start and stop pattern are sent to signify the begin and end of a message.
 *  
 * The library is based on the article published by Adrian Mills:
 * http://www.quickbuilder.co.uk/qb/articles/Manchester_encoding_using_RS232.pdf 
 */

#ifndef MANCHESTERUART_H
#define MANCHESTERUART_H

#include "mbed.h"
#include "ManchesterMsg.h"

#define START 0xF0          // start pattern
#define STOP  0x0F          // stop pattern

class   ManchesterUART
{
    enum Error
    {
        NO_ERROR,
        ILLEGAL_CODE,
        RX_TIMEOUT,
        BUF_OVERRUN
    };

public:
    /**
     * @brief   Creates a ManchesterUART object
     * @note
     * @param   txPin Pin name of transmitter line
     *          rxPin Pin name of receiver line
     *          speed Communication bit rate in bits per second. Defaults to 9600bps
     *          timeout Receive timeout in seconds. Defaults to 5 seconds.
     * @retval
     */
    ManchesterUART(PinName txPin, PinName rxPin, int speed = 9600, float timeout_sec = 5) :
        _serial(txPin, rxPin, speed), _timeout_sec(timeout_sec), _error(NO_ERROR) {}

    ~ManchesterUART(void) { }
    void    transmit(ManchesterMsg& msg);
    bool    receive(ManchesterMsg& msg);
    Error   lastError() { return _error; }

private:
    Serial  _serial;
    char*   _data;          // data array
    size_t  _len;           // data length in bytes
    size_t  _maxLen;        // maximum length
    Timeout _timeout;       // timeout
    float   _timeout_sec;   // timeout in seconds
    Error   _error;         // error flag

    void    rxTimeout(void);
    void    transmitByte(uint8_t data);
    uint8_t receiveByte(void);
    uint8_t getNibble(uint8_t nibble);
};
#endif // MANCHESTERUART_H