Quantity   Component name
1 × Injector Test bench Made in China and as cheap as you can get. This one is the closest example to what I'm working with: https://goo.gl/p4DCWh
1 × Seeeduino Mega(ATmega2560) A Mega in the form factor of an Uno. It costs more than I'll ever again pay for an AVR, but I have it and it's done some great things for me. https://goo.gl/MvYbWs
1 × Adafruit LCD Shield Kit w/ 16x2 Character Display Only needs 5 wires: I2C, +, Gnd, and Reset. This is my window to controlling my controller and make the bench do something useful. https://www.adafruit.com/product/772
1 × RobotDyn 4 Relay Shield It's cheap and can handle the 19.2V the test bench uses to turn on/off the fuel pump and drain relays. https://goo.gl/dafcDU
1 × SainSmart Sensor Shield V4 I've got a love-hate relationship with these shields. I love how versatile they can be but hate a few aspects of their design. I pretty much desolder everything I don't need when I use these shields. For this project, this shield relays the I2C from the Mega to a 4 pin connector I soldered to the board. Then I soldered on a terminal to the reset line to send to my control panel. https://goo.gl/wjPCdC
1 × NKC Electronics Protoshield KIT for Arduino UNO R3 This is one of my favorite shields ever. This has enabled me to break out all kinds of voltages and signals to interface to other parts of my project. This shield is the only one I have which has 4 mounting screws. I mounted this to the exterior of the bench and then mount the LCD shield on this one. https://goo.gl/2T3Trg
1 × LM2596 DC to DC buck converter There are all kinds of variants of this available. I'm not sure which one I bought, but this https://goo.gl/CMYbnU is the closest I could find. I convert the 20V from the test bench to 7.2 to power the Mega. I monitor the +5V on the shields and will adjust the output of this module until the +5 steadies. THIS project wasn't as sensitive, but in times past, I've had I2C not work at all below 5V.
1 × Digital O'scope OK, it's not a "component" per se, but fundamental for confirming the period and pulse width. This model seems the most like what I'm using: https://goo.gl/wMNDZu