Update

If anyone requests information on the original design of the VID, I would be happy to assist them. However, I have sent this over all design back to be repacked. The current VID software and hardware supports most pre-1996 fuel injected automobiles--the functionality of the fuel economy hardware and algorithms are solid. The problems lies in the device mounting and packaging. In my case, the 1993 Honda Accord has a dash mounted clock. I recently removed this item (it was not working).. and realized that building the clock function into the VID and then installing it in the existing clock (footprint--if you will) might be a good way to finally get some use from the device. I have started to select a I2C based Real time clock chip to provide this feature. Now---that I have a I2C bus--- i am adding temperature sensors for both inside and outside the cab.. I am also adding analog monitoring capacity for other things. i.e. battery voltage measurement etc.

Bottom line.. (in case anyone is reading) the VID is going to be redesigned to work with multiple cpus. It will also be configured to run at 20 MHZ (not 8 MHZ) The clock chip will provide the main processor a reliable source of 32.768 KHZ---This means that fuel measurement system accuracy will no longer depend on the cpu's instruction clock and the timer divider, currently used to achieve 125 microsecond measurement granularity. The other feature needed was the addition of non-volatile static ram. The clock chip will provide about 56 bytes of static ram This storage will replace the flash storage currently used. One of the issued uncovered during long term testing was that flash can wear out-- since a some sort of non-switched power will be required for the clock--- it will also keep TRIP and TANK data alive.