File content as of revision 1:bd0ee507dd4c:

 /*-O//\         __     __
   |-gfo\       |__| | |  | |\ |
   |!y°o:\      |  __| |__| | \| v1.0
   |y"s§+`\     Giovanni Blu Mitolo 2012 - 2015
  /so+:-..`\    gioscarab@gmail.com
  |+/:ngr-*.`\
  |5/:%&-a3f.:;\     PJON is a device communications bus system that connects up to 255
  \+//u/+g%{osv,,\    arduino boards over one wire up to 5.29kB/s data communication speed.
    \=+&/osw+olds.\\   Contains acknowledge, collision detection, CRC and encpryption all done
       \:/+-.-°-:+oss\  with micros() and delayMicroseconds(), with no use of interrupts or timers.
        | |       \oy\\  Pull down resistor on the bus is generally used to reduce interference.
        > <
  _____-| |-________________________________________________________________________
 | BIT_WIDTH 20 | BIT_SPACER 56 | ACCEPTANCE  20 | READ_DELAY 8                     |
 |----------------------------------------------------------------------------------|
 |Transfer speed: 5.29kB/s     | Absolute bandwidth:  3.23 kB/s                     |
 |Baud rate:      42372 baud   | Data throughput:     2.68 kB/s                     |
 |__________________________________________________________________________________|

Copyright (c) 2012-2015, Giovanni Blu Mitolo All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
- Redistributions of source code must retain the above copyright
   notice, this list of conditions and the following disclaimer.

-  Redistributions in binary form must reproduce the above copyright
   notice, this list of conditions and the following disclaimer in the
   documentation and/or other materials provided with the distribution.

-  All advertising materials mentioning features or use of this software
   must display the following acknowledgement:
   This product includes PJON software developed by Giovanni Blu Mitolo.

-  Neither the name of PJON, PJON_ASK nor the
   names of its contributors may be used to endorse or promote products
   derived from this software without specific prior written permission.

This software is provided by the copyright holders and contributors"as is"
and any express or implied warranties, including, but not limited to, the
implied warranties of merchantability and fitness for a particular purpose
are disclaimed. In no event shall the copyright holder or contributors be
liable for any direct, indirect, incidental, special, exemplary, or consequential
damages (including, but not limited to, procurement of substitute goods or services;
loss of use, data, or profits; or business interruption) however caused and on any
theory of liability, whether in contract, strict liability, or tort (including
negligence or otherwise) arising in any way out of the use of this software, even if
advised of the possibility of such damage. */

#ifndef PJON_h
  #define PJON_h

  #include "mbed.h"

  /* COMPATIBILITY_MODE set to true:
  Run the network with a cautious speed to support all architectures.
  8Mhz devices will be able to communicate with 16 or more Mhz devices.
     COMPATIBILITY_MODE set to false:
  Run the network at full speed with the best performances, but is
  indicated only for networks made by a group of devices with the
  same architecture / processor (for example 10 Arduino Uno) */

  #define  COMPATIBILITY_MODE true

//mbed (needs tweaking)
      #define BIT_WIDTH 45
      #define BIT_SPACER 115
      #define ACCEPTANCE 39
      #define READ_DELAY 25

  /* The following constants setup are quite conservative and determined only
     with a huge amount of time and blind testing (without oscilloscope)
     tweaking values and analysing results. Theese can be changed to obtain
     faster speed. Probably you need experience, time and an oscilloscope. */

  #if defined(__AVR_ATmega88__) || defined(__AVR_ATmega168__) || defined(__AVR_ATmega328__) || defined(__AVR_ATmega328P__)
    #if (F_CPU == 16000000 && !COMPATIBILITY_MODE)
      #define BIT_WIDTH 20
      #define BIT_SPACER 56
      #define ACCEPTANCE 20
      #define READ_DELAY 8
    #endif
    #if (F_CPU == 8000000 || COMPATIBILITY_MODE)
      #define BIT_WIDTH 40
      #define BIT_SPACER 112
      #define ACCEPTANCE 40
      #define READ_DELAY 16
    #endif
  #endif

  #if defined(__AVR_ATmega1280__) || defined(__AVR_ATmega2560__)
    #if (F_CPU == 16000000 && !COMPATIBILITY_MODE)
      /* Mega has shorter values than Duemianove / Uno because
      micros() produces longer delays on ATmega1280/2560 */
      #define BIT_WIDTH 18
      #define BIT_SPACER 54
      #define ACCEPTANCE 18
      #define READ_DELAY 8
    #endif
    #if (F_CPU == 8000000 || COMPATIBILITY_MODE)
      /* Mega has shorter values than Duemianove / Uno because
      micros() produces longer delays on ATmega1280/2560 */
      #define BIT_WIDTH 38
      #define BIT_SPACER 110
      #define ACCEPTANCE 38
      #define READ_DELAY 16
    #endif
  #endif

  #if defined(__AVR_ATtiny45__) || defined(__AVR_ATtiny85__)
    #if (F_CPU == 8000000 || COMPATIBILITY_MODE) // Internal clock
      /* ATtiny has shorter values than Duemianove / Uno because
      micros() produces longer delays on ATtiny45/85 */
      #define BIT_WIDTH 35
      #define BIT_SPACER 108
      #define ACCEPTANCE 35
      #define READ_DELAY 16
    #endif
  #endif

#endif

// Protocol symbols
#define ACK        6
#define NAK        21
#define FAIL       0x100
#define BUSY       666
#define BROADCAST  124
#define TO_BE_SENT 74

// Errors
#define CONNECTION_LOST 101
#define PACKETS_BUFFER_FULL 102
#define MEMORY_FULL 103

// Maximum sending attempts before throwing CONNECTON_LOST error
#define MAX_ATTEMPTS 250

// Packets buffer length, if full PACKET_BUFFER_FULL error is thrown
#define MAX_PACKETS 10

// Max packet length, higher if necessary (affects memory)
#define PACKET_MAX_LENGTH 50

struct packet {
  uint8_t attempts;
  uint8_t device_id;
  char *content;
  uint8_t length;
  unsigned long registration;
  int state;
  unsigned long timing;
};

typedef void (* receiver)(uint8_t length, uint8_t *payload);
typedef void (* pjon_error)(uint8_t code, uint8_t data);

static void dummy_error_handler(uint8_t code, uint8_t data) {};

class PJON {

  public:
    PJON(PinName input_pin);
    PJON(PinName input_pin, uint8_t id);

    void initialize();

    void set_id(uint8_t id);
    void set_receiver(receiver r);
    void set_error(pjon_error e);

    int receive_byte();
    int receive();
    int receive(unsigned long duration);

    void send_bit(uint8_t VALUE, int duration);
    void send_byte(uint8_t b);
    int  send_string(uint8_t id, char *string, uint8_t length);
    int  send(uint8_t id, char *packet, uint8_t length, unsigned long timing = 0);

    void update();
    void remove(int id);

    uint8_t read_byte();
    bool can_start();

    uint8_t syncronization_bit();

    uint8_t data[PACKET_MAX_LENGTH];
    packet  packets[MAX_PACKETS];

  private:
    DigitalInOut _input_pin;
    uint8_t   _device_id;
    //int       _input_pin;
    receiver  _receiver;
    pjon_error     _error;
    Timer _reg_timer;
};