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

Depth CAN Message 81h,F5h,0Bh,11h, 08h, 01h, 01h,08h,00h,00h, 00h,01h, 00h 81 F5 0B 00 08 01 C9 08 00 00 00 01 00 81 F5 0B 00 08 01 F0 0A 00 00 00 01 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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