philpem

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Datasheets

	; This is a first pass attempt at making a Pi Zero PIO module handle zero-bit stuffing and flag transmission
	; It will need cycle delays adding, etc. to turn it into usable code.
	; I got half-way through it, then realised it wasn't going to work for my use case (NABU Adaptor packet generation) because
	; the NABU Adaptor has a LFSR-based bitstream randomizer (scrambler) after the SDLC block.
	;
	; Set up autopull, and a bit length of 9 (if such a thing is possible, I haven't checked).
	; The first bit shifted is a 0 for normal data, or a 1 for 'raw' sending, which is used to send flags (0x17E).

	.program sdlc
	.side_set 1

	// This code takes the Electronic Serial Number (ESN) of an MPT1327 radio and calculates the 8-bit Check Byte
	// as defined in MPT1343 section 7.
	// This algorithm was formerly secret - one would have to ask the Radiocommunications Agency for a copy.
	//
	// The original intent was to stop radios from being illicitly cloned using only tha information on the label.
	// Unfortunately the radio transmits the check byte (the whole thing) as part of the network registration sequence,
	// so it does precisely nothing if you can sniff a radio registraion request on the control uplink channel.
	//
	// These days it's of historical interest, or of interest to people who are curious about MPT1327/MPT1343 (or whether
	// their fellow hams have figured out how to change their radios' ESNs... if you know any hams using MPT/Taitnet kit)