4 NMRA packets from the computer to the PIC should consist of 8-bit bytes.
6 bits 6-0 contain the data to be sent to the track
7 bit 7 is 1 if the byte is the last in the packet and 0 otherwise
9 The first 14 data bits in the NMRA packet should be 1s.
10 (i.e. the first two complete bytes should be 01111111 01111111)
11 (packets beginning with some other sequence are reserved for non-NMRA messages)
13 Maximum NMRA message length = 15 bytes (i.e. 105 bits).
14 Messages longer than this will cause things to get confused at the moment.
17 most significant bit first
22 Reserved access bank locations
23 ==============================
29 Flash memory ID locations
30 =========================
32 (Buffer page 50 0000h reserved for NMRA)
33 (Buffer page 40 0000h reserved for i2c)
34 (Buffer page 50 0000h reserved for error codes)
39 (guaranteed to be in range 0..31 inclusive)
43 bit 7 1 for the main PIC (#0)
45 0-6 currently unused, set to 0
47 Bytes 30 0000h - 3f ffffh
48 reserved for error messages, each 8 bytes long
56 (slave addresses will be 10xxxxx where xxxxx=PIC number above)