Communication protocol between CAN and CC2540 chip. [[BR]]

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  

Command message structure
 1. Command code (1 byte)
 2. Payload size (1 byte)
 3. Payload (0 - 255 bytes)


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

}}}


Examples
 0x01:0x08:0x00:0x00:0x07:0x06:0x00:0x01:0x05:0x05
 1. byte - subsribe command
 2. byte - payload size 8 byte = 2 CAN message IDs * 4 byte each 
 3. - 10. bytes 0076h & 0155h