Oh nice. Here’s a list of the PGNs the starfire transmits (and are required by autotrac) that I know about:
65267 - industry standard GPS position pgn
65256 - industry standard vehicle attitude pgn
65535 - proprietary, two different messages, first byte is type of message:
0x53 - GPS acccuracy level
0xe1 - TCM information

I’ll describe the layout of the messages in more detail later today. I’m hoping that if you generate these messages, autotrac will function even if the monitor does not show a starfire attached.

I neglected to mention Starfire receivers always broadcast from the source address of 28.

Okay for pgn 65267, it’s divided up into the following fields:
bytes 0-3 - unsigned integer for latitude. divide by 128 subtract 200 to get degrees
bytes 4-7 - unsigned integer for longitude. divide by 128 subtract 200 to get degrees

pgn 65256 - vehicle direction and speed
bytes 0-1 - compass bearing divide by 128 to get degrees
bytes 2-3 - vehicle speed divide by 256 to get km/h
bytes 4-5 - vehicle pitch divide by 128, subtract 200 to get degrees
bytes 6-7 - altitude divide by 125, subtract 2500 to get metres

pgn 65535
if byte 0 is 0x53, it’s information about GPS type
byte 3 is the current GPS type and accuracy level. For example, SF1 at 30% accuracy would be 0x43. SF1 at full accuracy would be 0x49.
byte 4 is the “licensed” GPS type. Should be “0x40” for SF1

if byte 0 is 0xe1, it’s TCM information:
bytes 2-3 roll angle, divide by 128 subtract 200 to get degrees

Everything else I’m not sure of. There are several other 65535 messages that come from the GPS receiver. I have not yet analyzed them.

Here’s a short data dump from the GPS receiver (28) to the broadcast address (255) of the proprietary 65535 messages, only some of which I understand. First number is a timestamp in milliseconds. So every 200 ms you get a clump of messages.

timestamp, pgn, priority, src, dest, 8 byte payload
5816, 65535, 5, 28, 255, e0 01 04
5829, 65535, 3, 28, 255, 51 03 02 09 15 0b 12 02
5830, 65535, 3, 28, 255, 52 05 a1 60 42 b1 ba 9a
5830, 65535, 6, 28, 255, 53 01 8f 44 40 10 41 54 ← this line has the GPS type information
5831, 65535, 6, 28, 255, 54 00 00 16 89 2a ba 14
5831, 65535, 2, 28, 255, e1 e0 f5 63 6f 64 00 fa ← this is TCM, roll angle bytes 2-3
6026, 65535, 3, 28, 255, 51 03 02 09 15 0b 12 02
6027, 65535, 3, 28, 255, 52 05 a1 60 42 cb 8e 9d
6027, 65535, 6, 28, 255, 53 01 8f 44 40 10 41 54
6028, 65535, 6, 28, 255, 54 00 00 16 89 2a ba 14
6028, 65535, 2, 28, 255, e1 e0 f5 63 6b 64 00 fa
6226, 65535, 3, 28, 255, 51 03 02 09 15 0b 12 02
6227, 65535, 3, 28, 255, 52 05 a1 60 42 b6 79 9f
6227, 65535, 6, 28, 255, 53 01 8f 44 40 10 41 54
6228, 65535, 6, 28, 255, 54 00 00 16 89 2a ba 14
6228, 65535, 2, 28, 255, e1 e0 f5 63 4c 64 00 fa
6426, 65535, 3, 28, 255, 51 03 02 09 15 0b 12 02
6427, 65535, 3, 28, 255, 52 05 a1 60 42 b6 79 a4
6427, 65535, 6, 28, 255, 53 01 8f 44 40 10 41 54
6428, 65535, 6, 28, 255, 54 00 00 16 89 2a ba 14
6428, 65535, 2, 28, 255, e1 e0 f5 63 76 64 00 fa
6626, 65535, 3, 28, 255, 51 03 02 09 15 0b 12 02
6627, 65535, 3, 28, 255, 52 05 a1 60 42 a0 4d a1
6627, 65535, 6, 28, 255, 53 01 8f 44 40 10 41 54
6628, 65535, 6, 28, 255, 54 00 00 16 89 2a ba 14
6628, 65535, 2, 28, 255, e1 e0 f5 63 6b 64 00 fa
6816, 65535, 5, 28, 255, e0 01 04
6829, 65535, 3, 28, 255, 51 03 02 09 15 0b 12 02
6830, 65535, 3, 28, 255, 52 05 a1 60 42 0c 63 a8
6830, 65535, 6, 28, 255, 53 01 8f 44 40 10 41 54
6831, 65535, 6, 28, 255, 54 00 00 16 89 2a ba 14
6831, 65535, 2, 28, 255, e1 e0 f5 63 5b 64 00 fa
7026, 65535, 3, 28, 255, 51 03 02 09 15 0b 12 01
7027, 65535, 3, 28, 255, 52 05 a1 60 42 4e 79 bd
7027, 65535, 6, 28, 255, 53 01 8f 44 40 10 41 54
7028, 65535, 6, 28, 255, 54 00 00 16 89 2a ba 14
7028, 65535, 2, 28, 255, e1 e0 f5 63 55 64 00 fa
7226, 65535, 3, 28, 255, 51 03 02 09 15 0b 12 01
7227, 65535, 3, 28, 255, 52 05 a1 60 42 63 79 c4
7227, 65535, 6, 28, 255, 53 01 8f 44 40 10 41 54
7228, 65535, 6, 28, 255, 54 00 00 16 89 2a ba 14
7228, 65535, 2, 28, 255, e1 e0 ef 63 76 64 00 fa
7426, 65535, 3, 28, 255, 51 03 02 09 15 0b 12 01
7427, 65535, 3, 28, 255, 52 05 a1 60 42 0c 63 c2
7427, 65535, 6, 28, 255, 53 01 8f 44 40 10 41 54
7428, 65535, 6, 28, 255, 54 00 00 16 89 2a ba 14
7428, 65535, 2, 28, 255, e1 e0 ef 63 53 64 00 fa
7626, 65535, 3, 28, 255, 51 03 02 09 15 0b 12 01
7627, 65535, 3, 28, 255, 52 05 a1 60 42 f7 8e bf
7627, 65535, 6, 28, 255, 53 01 8f 44 40 10 41 54
7628, 65535, 6, 28, 255, 54 00 00 16 89 2a ba 14
7628, 65535, 2, 28, 255, e1 e0 ef 63 4c 64 00 fa
7816, 65535, 5, 28, 255, e0 01 04
7829, 65535, 3, 28, 255, 51 03 02 09 15 0b 12 01
7830, 65535, 3, 28, 255, 52 05 a1 60 42 38 63 c2
7830, 65535, 6, 28, 255, 53 01 8f 44 40 10 41 54
7831, 65535, 6, 28, 255, 54 00 00 16 89 2a ba 14
7832, 65535, 2, 28, 255, e1 e0 ef 63 62 64 00 fa
8026, 65535, 3, 28, 255, 51 03 02 09 15 0b 12 01
8027, 65535, 3, 28, 255, 52 05 a1 60 42 e5 22 cf
8027, 65535, 6, 28, 255, 53 01 8f 44 40 10 41 54
8028, 65535, 6, 28, 255, 54 00 00 16 89 2a ba 14
8028, 65535, 2, 28, 255, e1 e0 f5 63 57 64 00 fa
8226, 65535, 3, 28, 255, 51 03 02 09 15 0b 12 01
8227, 65535, 3, 28, 255, 52 05 a1 60 42 fb 79 ce
8227, 65535, 6, 28, 255, 53 01 8f 44 40 10 41 54
8228, 65535, 6, 28, 255, 54 00 00 16 89 2a ba 14
8228, 65535, 2, 28, 255, e1 e0 f5 63 38 64 00 fa
8426, 65535, 3, 28, 255, 51 03 02 09 15 0b 12 01
8427, 65535, 3, 28, 255, 52 05 a1 60 42 3c cf c6
8427, 65535, 6, 28, 255, 53 01 8f 44 40 10 41 54
8428, 65535, 6, 28, 255, 54 00 00 16 89 2a ba 14
8428, 65535, 2, 28, 255, e1 e0 f5 63 57 64 00 fa
8626, 65535, 3, 28, 255, 51 03 02 09 15 0b 12 01
8627, 65535, 3, 28, 255, 52 05 a1 60 42 e5 63 d4
8627, 65535, 6, 28, 255, 53 01 8f 44 40 10 41 54
8628, 65535, 6, 28, 255, 54 00 00 16 89 2a ba 14
8628, 65535, 2, 28, 255, e1 e0 f5 63 54 64 00 fa
8816, 65535, 5, 28, 255, e0 01 04
8829, 65535, 3, 28, 255, 51 03 02 09 15 0b 12 01
8830, 65535, 3, 28, 255, 52 05 a1 60 42 27 63 d4
8830, 65535, 6, 28, 255, 53 01 8f 44 40 10 41 54
8831, 65535, 6, 28, 255, 54 00 00 16 89 2a ba 14
8832, 65535, 2, 28, 255, e1 e0 f5 63 3e 64 00 fa
9026, 65535, 3, 28, 255, 51 03 02 09 15 0b 12 01
9027, 65535, 3, 28, 255, 52 05 a1 60 42 fb 7d f5
9027, 65535, 6, 28, 255, 53 01 8f 44 40 10 41 54
9028, 65535, 6, 28, 255, 54 00 00 16 89 2a ba 14
9029, 65535, 2, 28, 255, e1 e0 ef 63 50 64 00 fa
9226, 65535, 3, 28, 255, 51 03 02 09 15 0b 12 01
9227, 65535, 3, 28, 255, 52 05 a1 60 42 3c 3c e7
9227, 65535, 6, 28, 255, 53 01 8f 44 40 10 41 54
9228, 65535, 6, 28, 255, 54 00 00 16 89 2a ba 14
9228, 65535, 2, 28, 255, e1 e0 ef 63 49 64 00 fa
9426, 65535, 3, 28, 255, 51 03 02 09 15 0b 12 01
9427, 65535, 3, 28, 255, 52 05 a1 60 42 fb 52 ef
9427, 65535, 6, 28, 255, 53 01 8f 44 40 10 41 54
9428, 65535, 6, 28, 255, 54 00 00 16 89 2a ba 14
9428, 65535, 2, 28, 255, e1 e0 f5 63 4f 64 00 fa
9626, 65535, 3, 28, 255, 51 03 02 09 15 0b 12 01
9627, 65535, 3, 28, 255, 52 05 a1 60 42 27 52 e3
9627, 65535, 6, 28, 255, 53 01 8f 44 40 10 41 54
9628, 65535, 6, 28, 255, 54 00 00 16 89 2a ba 14
9628, 65535, 2, 28, 255, e1 e0 f5 63 1a 64 00 fa
9816, 65535, 5, 28, 255, e0 01 04