Building a custom Arduino-controlled ‘analog’ dashboard

The folks over at Bad Obsession Motorsport in the UK specialize in unusual automotive builds, from a four-wheel drive Austin Mini to custom camper van called The Escargot. While working on that Mini, which they’ve dubbed “Binky,” they realized that they’d need create their own custom instrument cluster. But they wanted it to look appropriate for the classic car, so they used Arduino boards to build this “analog” dashboard.

This started as a more modest project. The Bad Obsession Motorsport team just wanted to add LED lighting to existing gauges. Off-the-shelf LED controller solutions lacked the kind of brightness control they wanted and so they began experimenting with Arduino boards. They found that brightness control via PWM (pulse-width modulation) is trivial with an Arduino UNO Rev3 and so, emboldened by their success, they decided to expand the concept with new gauges.

Those new gauges indicate fuel level and coolant temperature. They have moving needles and look like they’re analog, but they’re actually digitally controlled by Arduino boards. Small hobby servo motors move the needles according to readings taken by a float sensor and a temperature sensor, gathered by an Arduino Nano Every board through its analog pins.

The Bad Obsession Motorsport team did have trouble with the lighting control and the servo control interfering with each other (likely an issue with either power draw or a code glitch), so they split those into two separate systems. One Nano controls the LEDs and a second Nano controls the gauge servos.

The final challenge was returning the servos to their “home” positions after turning the car off. Because all of the power comes from the car’s electrical system and that disconnects when the key is removed, they used capacitors to store a bit of extra juice. When the Arduino detects the power disconnect, it immediately moves the servos to their home positions. Then they’re ready to go the next time the car starts up.