160 Baud ALDL Display

Juha Niinikoski Juha.Niinikoski@mikrolog.fi 27.9.2000

This simple "one evening" project is 160 Baud ALDL display / simple scan tool. I did this mainly for my Rover 3.5 efi conversion tuning. There are no extensive user manuals and other documents available. This document, included schematics and software source file are all that you have. Schematics are hand drawn because I don't have any design tools to do it better. I have tested this only with 1227747 ECM but it should work also with other 160 baud units after you have verified / altered ALDL data stream decoding to match with your application. I also found 1227747 bit timing little different what Peter Gargano have documented at his 160 Baud ALDL pages. My 747 bit timing appears to be:

• Start bit 369 uS
• data bit 4041 uS
• stop bit 1890 uS
• = 6300 uS total.

I have used VFD (vacuum fluorescent display) but you can as well use standard 4 * 20 LCD in this project. VFD is however brighter and gives better contrast. Of course any other format LCD is also usable but you have to format your display pages according it. Picture at left shows my hardware setup. Partcount is so low that you can easily build this circuit on breadboard.