Communication protocol between CAN and CC2540 chip

• ​http://en.wikipedia.org/wiki/CAN_bus
• ​NMEA2000 principles
• ​NMEA2000 message dictionary

List of commands from CC2540 to CAN transiver:

1. Subscribe to a message
2. Subscribe to a message with a bitmask
3. Unsubscribe from messages
4. Unsubscribe from messages with a bitmask
5. List of all subscriptions
6. Reset filter state
7. Passthrough message

enum {
  CMD_SUBSCRIBE = 1,
  CMD_SUBSCRIBE_BITMASK,
  CMD_UNSUBSCRIBE,
  CMD_UNSUBSCRIBE_BITMASK,
  CMD_LIST,
  CMD_RESET,
  CMD_MSG
} cmd_type;

List of responces from CAN transiver:

enum {
  ACK_SUBSCRIBE = 1,
  ACK_SUBSCRIBE_BITMASK,
  ACK_UNSUBSCRIBE,
  ACK_UNSUBSCRIBE_BITMASK,
  ACK_LIST,
  ACK_RESET,
  ACK_MSG
} cmd_type;

Command message structure

Byte	Bitmask	Description	Values
0		Command code	1 - 7
1		Payload size	0 - 254
2 - 255		Payload

Examples

   01:08:00:76:01:55:02:44:00:01
   04:02:00:76
   05:00
   06:00 
   07:07:FF:05:01:02:03:04:05
   07:01:67:02:00:05

Command	Length	Payload
1 byte	1	n
01	08	76:01:55:02:44:00:01
Subscribe	2 CAN message IDs, 4 byte each

Temp Message
81 FD 06 00 08 01 1B 01 16 01 84 03 00
81 FD 06 00 08 01 25 01 20 01 84 03 00
81 FD 06 00 08 01 2A 01 25 01 84 03 00

Speed Message
81 F5 03 00 07 01 0A 00 0C 00 00 00
81 F5 03 00 07 01 0D 00 0F 00 00 00
81 F5 03 00 07 01 17 00 19 00 00 00

Log Message
81 F5 03 00 11 01 B0 3D 81 09 00 00 B0 04 00 00 64 00 00 00 00 00
81 F5 03 00 11 01 B0 3D 91 30 00 00 78 05 00 00 2C 01 00 00 00 00
81 F5 03 00 11 01 B0 3D 99 35 00 00 78 07 00 00 2D 02 00 00 00 00

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Standard CAN message example:  ID=76h
byte0 - 07h        (incoming CAN MESSAGE)               
byte1 - 00h    (00h=b00000000 bit.7=0 standard message)  (this is byte.1 of std.ID      excluding high 5 bits in this byte) 
    //if byte1 bit7=0 expect 1 more byte for ID

byte2 - 76h                                     	 (this is byte.0 of std.ID) 
byte3 - DLC        (message data length code. also the payload.  8 in this example)
   byte4 - 01h	(byte.0 of data)
   byte5 - 02h	(byte.1 of data)
   byte6 - 03h	(byte.2 of data)
   byte7 - 04h	(byte.3 of data)
   byte8 - 05h	(byte.4 of data)
   byte9 - 06h	(byte.5 of data)
   byte10 - 07h	(byte.6 of data)
   byte11 - 08h	(byte.7 of data)

std.ID example 1 (ID=76h)
07h, 00h,76h, 08h, 01h,02h,03h,04h,05h,06h,07h,08h

std.ID example 2 (ID=5DFh)
07h, 05h,DFh, 08h, 01h,02h,03h,04h,05h,06h,07h,08h
-------------------------------------------------

-------------------------------------------------
Extended CAN message example:  ID=76h
byte0 - 07h        (incoming CAN MESSAGE)               
byte1 - 80h    (80h=b10000000 bit.7=1 extended message )     (this is byte.3 of ext.ID excluding  high 3 bits in this byte)
    //if byte1 bit7=1 expect 3 more bytes for ID
    byte2 - 00h                                              (this is byte.2 of ext.ID) 
    byte3 - 00h                                     	     (this is byte.1 of ext.ID) 
    byte4 - 76h                                     	     (this is byte.0 of ext.ID) 
byte5 - DLC        (message data length code. also the payload.  8 in this example)
   byte6 - 01h	(byte.0 of data)
   byte7 - 02h	(byte.1 of data)
   byte8 - 03h	(byte.2 of data)
   byte9 - 04h	(byte.3 of data)
   byte10 - 05h	(byte.4 of data)
   byte11 - 06h	(byte.5 of data)
   byte12 - 07h	(byte.6 of data)
   byte13 - 08h	(byte.7 of data)

ext.ID example 1 (ID=76h  ( b00000000000000000000000001110110 ))
07h, 80h,00h,00h,76h, 08h, 01h,02h,03h,04h,05h,06h,07h,08h

ext.ID example 2 (ID=12345678h    ( b00010010001101000101011001111000 ))
07h, 92h,34h,56h,78h, 08h, 01h,02h,03h,04h,05h,06h,07h,08h

ext.ID example 3 (ID=1FFFFFFFh    ( b00011111111111111111111111111111  29 bits, max value of ext.ID))
07h, 9Fh,FFh,FFh,FFh, 08h, 01h,02h,03h,04h,05h,06h,07h,08h
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