I'm trying to reverse engineer the protocol used by a fairly old video intercom. Using a UART logic analyser was able to guess the baud rate, data bits, start/stop bit. It idles at 14v and pulls to GND for 0.
when I press the same sequence repeatedly of buttons I get the following bytes:
PREAMBLE (sent when waking up unit): 0x02 0x16 0x10 0x10 0x10 0x10 0x10 0x10 0x11 0x11 0x18 0x03 VIDEO ON: 0x02 0x3c 0x31 0x09 0x38 0x25 0x11 0x6f 0x00 0x1e 0x71 0x03 0x02 0x3d 0x11 0x6f 0x00 0x1e 0x31 0x09 0x38 0x25 0x72 0x03 MIC ON: 0x02 0x4a 0x31 0x09 0x38 0x25 0x11 0x6f 0x00 0x1e 0x7f 0x03 0x02 0x4c 0x11 0x6f 0x00 0x1e 0x31 0x09 0x38 0x25 0x01 0x03 UNLOCK DOOR: 0x02 0x38 0x31 0x09 0x38 0x25 0x31 0x45 0x11 0x1e 0x74 0x03 0x02 0x3a 0x31 0x09 0x38 0x25 0x11 0x6f 0x00 0x1e 0x6f 0x03
Does this appear to be a protocol standard of any kind of control system?
EDIT: Here is the best I could understand: https://docs.google.com/spreadsheets/d/e/2PACX-1vQRyUafqa6CEMd9BOOyAWO4OKGXNKsGLvs6epR5PjqnqBRMbpWOqz2-ij51mFDz4lBUOcVSR7jxK505/pubhtml?gid=1867863786&single=true
It seems as though the format is as follows: BYTE1 = STX BYTE2 = COMMAND BYTE3,4,5,6 = SRC BYTE7,8,9,10 = DST BYTE11 = SUM of BYTE2 BYTE10 trimmed to 8-bit