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 theManchester.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:
ACKNOWLEDGEMENT: The code in this library was based on this article published by Robert Guastella.
Import programManchester_Transmitter
Manchester transmitter demo.
Import programManchester_Receiver
Manchester receiver demo.
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
- Committer:
- hudakz
- Date:
- 2017-05-17
- Revision:
- 0:d5c75b0e5708
- Child:
- 1:11292d238e50
File content as of revision 0:d5c75b0e5708:
/* ****************************************************************************** * @file Manchester.h * @author Zoltan Hudak * @version * @date 16-May-2017 * @brief Manchester code for ARMmbed ****************************************************************************** * @attention * * <h2><center>© 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/>. */ #ifndef MANCHESTER_H #define MANCHESTER_H #include "mbed.h" #include "ManchesterMsg.h" class Manchester { enum State { IDLE, SYNCH_START, SYNCH_NEXT, SYNCH_END, SETUP, TRANSITION, COMPLETE, LISTEN, DECODE, ERROR }; public: Manchester ( PinName txPin, /* transmitter pin name */ PinName rxPin, /* receiver pin name */ uint32_t speed = 1500 /* speed in bits per second */, uint8_t tol = 20 /* pulse width tolerance (+/-) in % */ ); ~Manchester(void) { }; void transmit(ManchesterMsg& msg); bool receive(ManchesterMsg& msg); private: DigitalOut _tx; // transmitter line InterruptIn _rx; // receiver line Ticker _txTicker; // transmitter ticker Timeout _rxTimeout; // receiver timeout uint32_t _midBitTime; // mid-bit time [us] uint32_t _minPulseWidth; // minimum pulse width uint32_t _maxPulseWidth; // maximum pulse width State _state; // state char* _data; // data array uint8_t _len; // data length in bytes uint8_t _maxLen; // maximum length void transmission(void); void reception(void); void rxTimeout(void); }; #endif // MANCHESTER_H