Reverse Engineering the “MegaView Display for MegaSquirt”

Mack brought in this “MegaView Display for MegaSquirt” device many weeks ago. I spent some quality time with it, and while we think the vacuum display may be broken, or the connectors oxidized, I believe I’ve successfully replicated the noteable behaviors of the MegaView display for MegaSquirt with my new fantastic and fun Freeduino.

The MegaSquirt is an automotive embedded computer system that does custom fuel injection, with cool custom displays like this – with vacuum displays! which I’d never seen before. The MegaView uses a MC68HC908GP32CP FreeScale microcontroller, and I will be using the ATMEGA328P-PU based Arduino.

The first step was to connect the MegaView display to the the usb->rs323 adapter shown above, and connect to it with minicom – set to /dev/ttyUSB0, 115200 8N1, and observe how it handles inputs, and outputs.

The results of all my testing showed that the MegaView succeeded at displaying V’s about every second, taking no input, and doing nothing else.

After several hours/minutes of whiteboarding and reading through test examples, I came up with this program to emulate all of the known behaviors of the MegaView Display for MegaSquirt

Now my Freeduino also produces V’s!

Freeduino V2.0 Serial
Assembly Guide

Arduino IDE Guide
Arduino IDE Download Page (I followed the Linux instructions on BackTrack 4, but had to apt-get gcc-avr and avrdude.)
MegaSquirt FAQ

If you’d like like to see my work, contact me or meet me at the Familab. I’ll help you make one for yourself 😉

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