Created
January 6, 2017 20:58
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BY70-1 AX.25 command generator
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| #!/usr/bin/env python3 | |
| import binascii | |
| import sys | |
| def ax25call(callsign): | |
| s = callsign.split('-') | |
| call = s[0].upper()[:6] | |
| call = call + ' '*(6-len(call)) | |
| ssid = 0 if len(s) == 1 else int(s[1]) | |
| c = bytes(map(lambda c: c << 1, bytes(call, 'ascii'))) | |
| ss = bytes([0x60 | (ssid & 0xf) << 1 ]) | |
| return c + ss | |
| dst = ax25call(sys.argv[1]) | |
| src = ax25call(sys.argv[2]) | |
| cmd = binascii.a2b_hex(sys.argv[3].replace(' ', '')) | |
| packet = dst + src[:-1] + bytes([src[-1] | 1]) + b'\x03\xf0' + cmd | |
| kiss = b'\xc0\x00' + packet.replace(b'\xdb', b'\xdb\xdd').replace(b'\xc0', b'\xdb\xdc') + b'\xc0' | |
| sys.stdout.buffer.write(kiss) |
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I was looking over your article because I want to build my own program that sends AX.25 frames. I have some questions about this code. On line 11, why are you left shifting the ASCII characters ? What is the operation on line 12 supposed to do ?
Also, where can I find more information about the KISS and AX.25 specification so I can build something like this ?