DSC Keybus Protocol

Well I figured I should make a blogger for any Technical related crap I do and here I am, hopefully I can hack lots of nice things to post about in here. First thing up is DSC Keybus protocol which the propriatary protocol used by DSC in their alarm system keypads.

For the time being all I know about the protocol is that the clock line runs at 1kHz with 50% duty and oddly enough only does so for 41.6ms then it stays high for 5.4ms and starts all over again. The data line seems to transistion on either the falling or rising edge of the clock, which led Kortuk of chiphacker.com to belive that it is NRZ encoding which I'm not sure of yet but here are some OLS dumps of the data and clock lines hopefully I can figure this out and implement it with a old computer to keep tabs on door closes and opens ect.

Also there are some quite interesting reads out there that I'm using to help out:
My OLS Dumps
My Chiphacker Post
Wikipedia NRZ
AVR Freaks - Keybus Thread
PC-5401 Developer PDF

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