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.

Diff: Manchester.h

Revision:
2:de778df5892c
Parent:
1:11292d238e50
Child:
5:3b2c7e9fda3f
--- a/Manchester.h	Wed May 17 08:17:13 2017 +0000
+++ b/Manchester.h	Wed May 17 21:02:49 2017 +0000
@@ -2,7 +2,7 @@
  ******************************************************************************
  * @file    Manchester.h
  * @author  Zoltan Hudak
- * @version 
+ * @version
  * @date    16-May-2017
  * @brief   Manchester code for mbed
  ******************************************************************************
@@ -25,7 +25,7 @@
  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
 
@@ -47,35 +47,37 @@
         DECODE,
         ERROR
     };
-    
+
 public:
     Manchester
     (
         PinName     txPin,          /* transmitter pin name */
         PinName     rxPin,          /* receiver pin name */
-        uint32_t    speed = 1200    /* speed in bits per second */, 
-        uint8_t     tol = 20        /* pulse width tolerance (+/-) in % */ 
+        uint32_t    speed = 1200    /* speed in bits per second */,
+        uint8_t     tol = 20        /* pulse width tolerance (+/-) in % */
     );
-    ~Manchester(void) { };
+    ~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
+    Timeout     _timeout;       // timeout (watchdog)
     uint32_t    _midBitTime;    // mid-bit time [us]
     uint32_t    _minPulseWidth; // minimum pulse width [us]
     uint32_t    _maxPulseWidth; // maximum pulse width [us]
     State       _state;         // state
     char*       _data;          // data array
-    uint8_t     _len;           // data length in bytes
-    uint8_t     _maxLen;        // maximum length
-    
+    size_t      _len;           // data length in bytes
+    size_t      _maxLen;        // maximum length
+
     void        transmission(void);
     void        reception(void);
+    void        txTimeout(void);
     void        rxTimeout(void);
 };
 #endif // MANCHESTER_H
 
+