My goal was to create a display to monitor coolant temp and boost levels on my car without cluttering the interior up with lots of gauges. Since the car is already running on a Megasquirt 3 ECU, sensors already exist for most of the values that I would want to monitor. Because I was going to run a digital display, I also wanted to be able to make basic tuning adjustments to the car without requiring a laptop with me at all times.

Knowing that I want the ability to perform changes to the tune without a laptop, the two options I was considering were either a tablet or a Raspberry Pi based setup. I wasn't happy with any of the mounting solutions that I'd found for tablets, and was worried about the hardware performance compared to a Pi. Once I settled on a Raspberry Pi 4, it was time to choose the rest of the hardware involved.

• Raspberry Pi Official 7" Touchscreen
• Raspberry Pi 4 (4GB)
• HiFiBerry amp2
• Geekwork 2x20 Header Extender
• Raspberry Pi Terminal Block
• Future Improvements
  • 10 Amp Timer
  • Automotive Relays

The hardware stack I used had simplicity and compatibility at the front of my mind. When working with the Official 7" Touchscreen display, the Pi will mount to the standoffs on the back of the display. It simply connects with a ribbon cable for the display, and 4 wires run to the GPIO header for power and touchscreen controls.

1. Connect the video ribbon cable to the display.
2. When looking at the back of the display, connect the jumper wires front left to right, in the following order:
   • 5V (Red Wire)
   • Blank Pin (No Wire)
   • SDA (Green Wire)
   • SCL (Yellow Wire)
   • GND (Black Wire)
3. Attach the Raspberry Pi to the metal standoffs on the back of the display with the included machine screws. Make sure that the Pi is oriented properly to allow the ribbon cable from the display to connect to the Pi.
4. Attach the ribbon cable from the display to the Raspberry Pi.
5. (Optional) If you are skipping the HiFiBerry Amp2, then you will now need to connect the jumpers from the display to the GPIO headers on the Pi.
   • 5V (Red Wire) to pin 4
   • GND (Black Wire) to pin 6
   • SDA (Green Wire) to pin 3
   • SCL (Yellow Wire) to Pin 5

1. If your Pi is attached with screws to the standoffs on the Display, remove the screws and fasten the Pi to the display with appropriate sized standoffs.
2. Install the Amp2 onto the Pi by lining up the GPIO header.
   • The GPIO pins on the Amp2 are much shorter than the pins on the Pi. You may have issues with the jumper wires not being properly secured. If you want a better connection, I would recommend also adding a header extender and terminal block to make the wiring connections more secure and easier to work with.
3. Secure the Amp2 with machine screws or more standoffs depending on if you plan to add the header extender and terminal block.

I was not happy with the quality of the connection of the jumper wires to the Amp2 header. In order to get a better connection, I opted to add a header extender and a terminal block which allows me to create a very secure connection.

1. Install GPIO header extender.
2. Install standoffs of appropriate length.
3. Install terminal block.

The Amp2 will work with any input voltage from 12-24V. When powering the amp2, the display and Pi will also automatically power up. This means you can run this whole setup off of your 12V system in your car without requiring any step down voltage converters or buck converters.

• For bench testing, you will need to use a DC power supply that outputs anywhere from 12-24V.
• For installation in a vehicle, you can power this whole setup by tying into your switched ignition wire, and a ground wire. I bought a stereo harness and tapped into the switched ignition wire. I ran a separate dedicated ground wire to chassis ground.
• If you decided to run an Amp2 and plan to have functional speakers, you can wire your stereo harness directly to the speaker outputs on the Amp2. This makes wiring very simple and clean, and you have a stereo harness that can be removed with one plug and one ground wire.

• OpenAuto Pro
• TunerStudio Ultra

1. Purchase Open Auto Pro, available here: https://bluewavestudio.io/
2. Download Image and follow instructions here to flash image to SD Card - https://www.raspberrypi.org/documentation/installation/installing-images/
3. Boot system and enter Open Auto Pro serial number, system should now be ready for use.

Coming Soon...

• 3D Printed Mount for Raspberry Pi 7" Display

Coming soon...

• Hardware
  • https://www.raspberrypi.org/products/raspberry-pi-4-model-b/ Raspberry Pi 4 (4gb)
  • https://www.raspberrypi.org/products/raspberry-pi-touch-display/ Display
  • https://www.hifiberry.com/shop/boards/hifiberry-amp2/ Sound Card / 2 channel amplifier
  • http://timers.shop/6V-28V-10-Amp-Timer-POSITIVE-OUTPUT_p_13.html Current Timer
  • https://www.amazon.com/gp/product/B0827THC7R Geekwork 2x20 Header Extender
  • https://www.amazon.com/gp/product/B084C69VSQ/ Terminal Block
• Software
  • https://bluewavestudio.io/shop/openauto-pro-car-head-unit-solution/
  • http://tunerstudio.com/ TunerStudio Ultra
• 3D Printing
  • https://www.thingiverse.com/thing:4892851 Mount for 7" Display