Interprocessor (51-51d) protocol FAQ
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The 51d program running on the 7312 and the Winbond '51 chip communicate over /dev/ttyS1 at 115200 bps.
Here is what we know so far about the communications protocol:
7312 | 8052 | Possible Meaning |
---|---|---|
0xf9 | ?? | |
0x53 | ?? | |
0x10 | ?? | |
0x21 | ?? | |
0x21,0xdf | Query total disc | |
0xce | ACK | |
0x7D | Total Disks followstd> | |
0xac | ?? | |
0x00 | First byte | |
0xbd | Continue | |
0x0f | Second Byte (total 15 disks) | |
0xbd | Continue | |
0x74 | End of Stream | |
0xce | ACK | |
0x20,0x00,0x01,0xdf | Query total tracks in disc 1 (0x00, 0x01) | |
0x66, 0x9a | 8052 PING | |
0xce | ACK | |
0x70 | 51d PONG | |
0xce | ACK | |
- Heartbeat:
If the Winbond chip does not see a "heartbeat" signal every 10 seconds, it will kill power to the 7312 and reboot it. It's a two-part sequence:
7312 > 0x70 0xAC < 51 > 0x90 0xCE < 51
Must repeat within 10 seconds, or the Winbond chip will output 0x66,0x9A 3 times and reboot.