Zoltan Hudak / Manchester Featured

Manchester code (phase encoding) library.

Dependents:   Manchester_Transmitter Manchester_Receiver

Manchester code (phase encoding) library

It implements Manchester code according to both IEEE 802.3 and G.E. Thomas' conventions.

  • A '0' is expressed by a high-to-low transition, a '1' by low-to-high transition in the IEEE 802.3 convention. The reverse is true in the G.E. Thomas' convention.
  • The transitions which signify '0' or '1' occur at the midpoint of a period.
  • Transitions at the start of a period are overhead and don't signify data.
  • Least significant bit is sent first
  • There are synchronization pulses (the number can be set) at the begin of transmission

    Select a convention to be used by commenting or uncommenting the line below in the Manchester.h header file.

Manchester.h

#define G_E_THOMAS 1

The IEEE 802.3 convention is used by default.

A Manchester encoded message (using G.E. Thomas' convention), with one sync pulse in the preamble, carrying four bytes:

/media/uploads/hudakz/manchester01.png

ACKNOWLEDGEMENT: The code in this library was based on this article published by Robert Guastella.

Import programManchester_Transmitter

Manchester transmitter demo.

Last commit 14 Oct 2018 by Zoltan Hudak


Import programManchester_Receiver

Manchester receiver demo.

Last commit 14 Oct 2018 by Zoltan Hudak

NOTE: To perform a simple test (without radio modules) connect the txPin on transmitter board to the rxPin on the receiver board and make sure that grounds are also connected one another.

Manchester.h@8:c1b5893191fe, 2018-10-14 (annotated)

Committer:
hudakz
Date:
Sun Oct 14 09:38:33 2018 +0000
Revision:
8:c1b5893191fe
Parent:
6:7454ad91f714 
Number of sync pulses in preamble can be set.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
hudakz 0:d5c75b0e5708 1 /*
hudakz 0:d5c75b0e5708 2 ******************************************************************************
hudakz 0:d5c75b0e5708 3 * @file Manchester.h
hudakz 0:d5c75b0e5708 4 * @author Zoltan Hudak
hudakz 2:de778df5892c 5 * @version
hudakz 6:7454ad91f714 6 * @date 2017-May-16
hudakz 1:11292d238e50 7 * @brief Manchester code for mbed
hudakz 0:d5c75b0e5708 8 ******************************************************************************
hudakz 0:d5c75b0e5708 9 * @attention
hudakz 0:d5c75b0e5708 10 *
hudakz 0:d5c75b0e5708 11 * <h2><center>&copy; COPYRIGHT(c) 2017 Zoltan Hudak <hudakz@outlook.com>
hudakz 0:d5c75b0e5708 12 *
hudakz 0:d5c75b0e5708 13 * All rights reserved.
hudakz 0:d5c75b0e5708 14
hudakz 0:d5c75b0e5708 15 This program is free software: you can redistribute it and/or modify
hudakz 0:d5c75b0e5708 16 it under the terms of the GNU General Public License as published by
hudakz 0:d5c75b0e5708 17 the Free Software Foundation, either version 3 of the License, or
hudakz 0:d5c75b0e5708 18 (at your option) any later version.
hudakz 0:d5c75b0e5708 19
hudakz 0:d5c75b0e5708 20 This program is distributed in the hope that it will be useful,
hudakz 0:d5c75b0e5708 21 but WITHOUT ANY WARRANTY; without even the implied warranty of
hudakz 0:d5c75b0e5708 22 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
hudakz 0:d5c75b0e5708 23 GNU General Public License for more details.
hudakz 0:d5c75b0e5708 24
hudakz 0:d5c75b0e5708 25 You should have received a copy of the GNU General Public License
hudakz 0:d5c75b0e5708 26 along with this program. If not, see <http://www.gnu.org/licenses/>.
hudakz 0:d5c75b0e5708 27 */
hudakz 5:3b2c7e9fda3f 28 /*
hudakz 5:3b2c7e9fda3f 29 This library implements Manchester code according to both IEEE 802.3
hudakz 6:7454ad91f714 30 and G.E. Thomas' conventions.
hudakz 5:3b2c7e9fda3f 31 • A '0' is expressed by a high-to-low transition, a '1' by low-to-high transition
hudakz 5:3b2c7e9fda3f 32 in the IEEE 802.3 convention. The reverse is true in the G.E. Thomas' convention.
hudakz 6:7454ad91f714 33 • The transitions which signify '0' or '1' occur at the midpoint of a period.
hudakz 5:3b2c7e9fda3f 34 • Transitions at the start of a period are overhead and don't signify data.
hudakz 5:3b2c7e9fda3f 35 • Least significant bit is sent first
hudakz 5:3b2c7e9fda3f 36 • There is one synchronization pulse at the begin of transmission
hudakz 5:3b2c7e9fda3f 37
hudakz 5:3b2c7e9fda3f 38 The IEEE 802.3 convention is used by default.
hudakz 5:3b2c7e9fda3f 39 Select a convention to be used by commenting or uncommenting
hudakz 5:3b2c7e9fda3f 40 the line "#define G_E_THOMAS 1" below.
hudakz 5:3b2c7e9fda3f 41 */
hudakz 0:d5c75b0e5708 42 #ifndef MANCHESTER_H
hudakz 0:d5c75b0e5708 43 #define MANCHESTER_H
hudakz 0:d5c75b0e5708 44
hudakz 0:d5c75b0e5708 45 #include "mbed.h"
hudakz 0:d5c75b0e5708 46 #include "ManchesterMsg.h"
hudakz 0:d5c75b0e5708 47
hudakz 8:c1b5893191fe 48 //Uncomment the following line to use G.E.Thomas' convention
hudakz 5:3b2c7e9fda3f 49
hudakz 5:3b2c7e9fda3f 50 //#define G_E_THOMAS 1
hudakz 5:3b2c7e9fda3f 51
hudakz 0:d5c75b0e5708 52 class Manchester
hudakz 0:d5c75b0e5708 53 {
hudakz 0:d5c75b0e5708 54 enum State
hudakz 0:d5c75b0e5708 55 {
hudakz 0:d5c75b0e5708 56 IDLE,
hudakz 0:d5c75b0e5708 57 SYNCH_START,
hudakz 0:d5c75b0e5708 58 SYNCH_NEXT,
hudakz 0:d5c75b0e5708 59 SYNCH_END,
hudakz 0:d5c75b0e5708 60 SETUP,
hudakz 0:d5c75b0e5708 61 TRANSITION,
hudakz 0:d5c75b0e5708 62 COMPLETE,
hudakz 0:d5c75b0e5708 63 LISTEN,
hudakz 8:c1b5893191fe 64 DECODE_START,
hudakz 0:d5c75b0e5708 65 DECODE,
hudakz 8:c1b5893191fe 66 STOP,
hudakz 0:d5c75b0e5708 67 ERROR
hudakz 0:d5c75b0e5708 68 };
hudakz 0:d5c75b0e5708 69 public:
hudakz 0:d5c75b0e5708 70 Manchester
hudakz 0:d5c75b0e5708 71 (
hudakz 1:11292d238e50 72 PinName txPin, /* transmitter pin name */
hudakz 1:11292d238e50 73 PinName rxPin, /* receiver pin name */
hudakz 5:3b2c7e9fda3f 74 uint32_t speed = 1200, /* speed in bits per second */
hudakz 8:c1b5893191fe 75 uint8_t tol = 25, /* pulse width tolerance (+/-) in % */
hudakz 8:c1b5893191fe 76 float rxTimeout = 5 /* receive timeout */
hudakz 0:d5c75b0e5708 77 );
hudakz 8:c1b5893191fe 78 ~ Manchester(void) { }
hudakz 0:d5c75b0e5708 79 void transmit(ManchesterMsg& msg);
hudakz 0:d5c75b0e5708 80 bool receive(ManchesterMsg& msg);
hudakz 8:c1b5893191fe 81 void setPreamble(uint8_t preamble) { _preamble = preamble; }
hudakz 8:c1b5893191fe 82 void setRxTimeout(float seconds) { _rxTimeout = seconds; }
hudakz 8:c1b5893191fe 83 char* lastError() { return _error; }
hudakz 0:d5c75b0e5708 84 private:
hudakz 8:c1b5893191fe 85 DigitalOut _tx; // transmitter line
hudakz 8:c1b5893191fe 86 InterruptIn _rx; // receiver line
hudakz 8:c1b5893191fe 87 Ticker _txTicker; // transmitter ticker
hudakz 8:c1b5893191fe 88 Timeout _timeout; // timeout (watchdog)
hudakz 8:c1b5893191fe 89 Timer _timer;
hudakz 8:c1b5893191fe 90 uint32_t _midBitTime; // mid-bit time [us]
hudakz 8:c1b5893191fe 91 uint32_t _minPulseWidth; // minimum pulse width [us]
hudakz 8:c1b5893191fe 92 uint32_t _maxPulseWidth; // maximum pulse width [us]
hudakz 8:c1b5893191fe 93 uint32_t _tol;
hudakz 8:c1b5893191fe 94 float _rxTimeout; // reception timeout [s]
hudakz 8:c1b5893191fe 95 State _state; // state
hudakz 8:c1b5893191fe 96 char* _data; // data array
hudakz 8:c1b5893191fe 97 size_t _len; // data length in bytes
hudakz 8:c1b5893191fe 98 size_t _maxLen; // maximum length
hudakz 8:c1b5893191fe 99 size_t _preamble; // number of start patterns
hudakz 8:c1b5893191fe 100 char* _error;
hudakz 0:d5c75b0e5708 101 void transmission(void);
hudakz 0:d5c75b0e5708 102 void reception(void);
hudakz 8:c1b5893191fe 103 void onTxTimeout(void);
hudakz 8:c1b5893191fe 104 void onRxTimeout(void);
hudakz 0:d5c75b0e5708 105 };
hudakz 0:d5c75b0e5708 106 #endif // MANCHESTER_H