Arduino + OBDII(VPW only) > 20x4 LCD display

Projects General Guidance
1

Im working on a standalone OBDII scanner and display for my car using an Arduino Uno. The car is a 1999 Pontiac Trans Am which uses the VPW protocol so ill be using an OBD VPW to RS232 interpreter chip. I think ill be powering the Arduino off the 8v off the 78L08 voltage regulator and tie arduino ground to chassis ground.

My questions are:
Are there any major software problems I may run in to?
Do I have enough power and signal isolation to protect the arduino (and my cars ECU)? (Do I need an opto-isolator or something?)
Any other foreseeable problems?
Thanks

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2

Optoisolator wont hurt, you will need a regulator if you arent using the onboard regulator on the arduino.

3

Can u post the code, here?
tks
:smiley:

4

I have build an almost identical design except that I am using the ELM327. I am also very interested in the code.