Packet structure

+---------------------------+
|         Signature         |
|         (5 Octets)        |
+---------------------------+
|          Version          |
|         (1 Octet)         |
+---------------------------+
|           Type            |
|         (1 Octet)         |
+---------------------------+
|          Options          |
|    (1 Octet, bitfield)    |
+---------------------------+
|          Payload          |
|     (Variable length)     |
+---------------------------+

Description

All multi-byte numerical fields are little-endian.

The signature field contains ASCII string "ZBNCP".

The version field is set to 0 (only this value is defined now).

The type field is set to 6.

Options bitfield

     7   6   5   4   3   2   1   0
   .   .   .   .   .   .   .   .   .
 0 +---+---+---+---+---+---+---+---+
   |     reserved      |b02|b01|b00|
+1 +---+---+---+---+---+---+---+---+

• b00 is set to 1 if transmitting from device to host, else 0
• b01 is set to 1 if host interrupt occurs
• b02 is set to 1 if both sides are transmitting at the same time
• b03–b07 are reserved for future use