The Arduino microcontroller is a core part of the modification and takes care of the following:
- Scanning all the hard buttons around the touchscreen for key presses
- Controls the input on the video controller board via i2c
- Monitors the ignition and interior light state to control the power to the Odroid computer
- Interfaces with the original touchscreen brightness control to control the backlight level of the new LCD panel
The connections to the ignition power state (Accessory power, or ACC) and the interior light are made via an opto-isolator to protect the input of the Arduino and convert the levels from 12v power to the 5v digital input level required by the Arduino.
Start by preparing the opto-isolator assembly:
Solder the 1k resistors to Pin 1 and Pin 4. Pin 1 is identified by a notch or dot on the top of the package. With the notch or dot on the left, Pin 1 is on your bottom left.
The Orange wire with crimped end goes to the end of the resistor on Pin 1
The 400mm Orange wire goes to the end of the resistor on Pin 4, and the 400mm Black wire goes to Pin 3
Solder the 70mm Blue wire to Pin 6, and the 70mm Purple to Pin 8.
On the underside, bend Pins 2,5 and 8 in a triangle formation so that they meet together. Then solder the Black 120mm wire across all 3 of these pins, which forms the common ground connection.
Cover the entire assembly with a length of heatshrink
Solder the two pins of connector to the 400mm Orange and Black wires, and insert into the housing
The opto assembly is ready
De-solder the power LED from the Arduino Leonardo
The mounting plate that will hold the Arduino, RTD Video board and USB power supply is laser cut from 2mm acrylic. Download a CAD file here.
You’ll need a number of nylon fasteners:
- Spacer M3 5mm+6mm x 10
- Spacer M3 10mm+6mm x 4
- Screw M3 5mm x 14
- Screw M3 8mm x 2
- Nut M3 x 10
Install the fasteners to the mounting plate as shown