ManchesterUART.h

00001 /*
00002  ******************************************************************************
00003  * @file    ManchesterUART.h
00004  * @author  Zoltan Hudak
00005  * @version
00006  * @date    2017-Nov-22
00007  * @brief   Manchester code over UART for mbed
00008  ******************************************************************************
00009  * @attention
00010  *
00011  * <h2><center>&copy; COPYRIGHT(c) 2017 Zoltan Hudak <hudakz@outlook.com>
00012  *
00013  * All rights reserved.
00014 
00015  This program is free software: you can redistribute it and/or modify
00016  it under the terms of the GNU General Public License as published by
00017  the Free Software Foundation, either version 3 of the License, or
00018  (at your option) any later version.
00019 
00020  This program is distributed in the hope that it will be useful,
00021  but WITHOUT ANY WARRANTY; without even the implied warranty of
00022  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00023  GNU General Public License for more details.
00024 
00025  You should have received a copy of the GNU General Public License
00026  along with this program.  If not, see <http://www.gnu.org/licenses/>.
00027  */
00028 /*
00029  * This library implements Manchester code using UART serial connection. Each
00030  * data byte is encoded into two bytes representing two nibbles of the original
00031  * data byte. These two bytes are then sent over UART serial link connection.
00032  * The receiver reconstructs the original data byte from the two bytes received.
00033  * A start and stop pattern are sent to signify the begin and end of a message.
00034  *
00035  * The library is based on the article published by Adrian Mills:
00036  * http://www.quickbuilder.co.uk/qb/articles/Manchester_encoding_using_RS232.pdf
00037  */
00038 #ifndef MANCHESTERUART_H
00039 #define MANCHESTERUART_H
00040 
00041 #include "mbed.h"
00042 #include "ManchesterMsg.h"
00043 
00044 #define START   0xF0    // start pattern
00045 
00046 #define STOP    0x0F    // stop pattern
00047 class   ManchesterUART
00048 {
00049     enum Error
00050     {
00051         NO_ERROR,
00052         ILLEGAL_CODE,
00053         RX_TIMEOUT,
00054         BUF_OVERRUN
00055     };
00056 public:
00057     /**
00058      * @brief   Creates a ManchesterUART object
00059      * @note
00060      * @param   txPin Pin name of transmitter line
00061      * @param   rxPin Pin name of receiver line
00062      * @param   preamble Number of start patterns at the begin of each transmission
00063      * @param   baudrate Communication bit rate in bits per second. Defaults to 115200bps
00064      * @param   timeout Receive timeout in seconds. Defaults to 5 seconds.
00065      * @retval
00066      */
00067     ManchesterUART
00068     (
00069         PinName txPin,
00070         PinName rxPin,
00071         int     baudrate = 9600,    /* bits/sec */
00072         uint8_t preamble = 8,       /* number of start patterns */
00073         float   rxTimeout = 5       /* seconds */
00074     ) :
00075     _serial(txPin, rxPin, baudrate),
00076     _rxTimeout(rxTimeout),
00077     _preamble(preamble),
00078     _error(NO_ERROR)
00079     { }
00080 
00081     ~       ManchesterUART(void)    { }
00082     void    transmit(ManchesterMsg& msg);
00083     void    attach(Callback<void ()> func, SerialBase::IrqType type = SerialBase::RxIrq)    { _serial.attach(func, type); }
00084     bool    receive(ManchesterMsg& msg);
00085     bool    readable()                      { return _serial.readable(); }
00086     void    baud(int baudrate)              { _serial.baud(baudrate); }
00087     void    setPreamble(uint8_t length)     { _preamble = length; }
00088     void    setRxTimeout(int seconds)       { _rxTimeout = seconds; }
00089     Error   lastError()                     { return _error; }
00090 private:
00091     Serial  _serial;
00092     char*   _data;      // data array
00093     size_t  _len;       // data length in bytes
00094     size_t  _maxLen;    // data maximum length
00095     Timeout _timeout;   // timeout
00096     float   _rxTimeout; // timeout time in seconds
00097     uint8_t _preamble;  // number of start patterns
00098     Error   _error;     // error flag
00099     void    rxTimeout(void);
00100     void    transmitByte(uint8_t data);
00101     uint8_t receiveByte(void);
00102     uint8_t getNibble(uint8_t nibble);
00103 };
00104 #endif // MANCHESTERUART_H