Easily Add a Gear Indicator to Your Car
Vaclav Krejci shows how you can add an Arduino-based gear indicator to your car without making any permanent modifications.
There are, sadly, very few new cars being offered today with stick shifts — at least in the United States. So if you’re the type of person who wants to enjoy the feeling of downshifting as you make a move to overtake a slow driver on a country road, then you might need to buy an older car. But the older you go, the less likely it is that that car will have a gear indicator. Luckily, that doesn’t have to influence your choice because Vaclav Krejci has a great guide that will help you add a gear indicator to any car.
Krejci’s project is clever, because it doesn’t require any complex mechanical parts or any modification of the car. If you decide to sell the car later, you can easily remove all of these components. But when they’re installed, you’ll get a nice display showing you the gear you’re in and a little diagram of the gear pattern to enhance that.
This doesn’t require any modification of the car because it relies on Hall effect sensors. Four of them surround the shifter lever. A collar-style permanent magnet attaches to the lever shaft, emitting a magnetic field. The Hall effect sensors detect the strength of that field, which correlates with distance. By measuring the relative strength of each, it is possible to calculate the position of the magnet — and therefore the shifter — on the same 2D plane as the sensors. Because the shifter position determines the selected gear, that calculation yields the current gear.
Krejci implemented that idea with a simple PCB that surrounds the shifter and positions the Hall effect sensors at the correct locations. An Arduino Uno Rev3 development board receives the sensor signals from the PCB through jumper wires. By keeping the Arduino separate from the PCB, Krejci made it easy to place it out of the way inside of a center console or under the trim. The screen — a small OLED — also connects via jumper wires. That lets the user mount the screen wherever they want, such as in an empty DIN slot on the dash.
As far as upgrades for cars go, it doesn’t get much better than this. This is an affordable and useful setup that just about anyone can perform without putting their vehicle at risk, because it is an entirely independent system.
