Since I have been doing so much work with electric cars and trying to make them more efficient I figured it was time to see home efficient my gasoline car is. So i designed this in-dash unit that monitors the car vitals like speed, mph, throttle position, airflow rate, fuel trim, and calculated mpg. then you can display any two that you like while you are driving.
I am using an ELM327 chip that allows me to talk to the car using serial commands instead of messing with the cars OBDII protocol. Since everything I was doing used serial, I decided to use a homebrew Basic Stamp 2 since it works great when dealing with multiple serial devices. When the switch on the panel is to the left it allows you to program the BS2, but flipping the switch to the right allows to connect your laptop directly to the ELM chip and run their custom software which allows you to clear check engine lights!