“This is a short project that I created as part of a larger RC build of a Lightweight Land Rover. I decided that I fancied having a working speedometer in the dashboard, but I knew that a servo wouldn’t cut it. There was only one reasonable option: deploy the arduino!
A bit of background to begin with… I am not a coding or electronics person. I still think of electricity in terms of water flow and am somewhat mystified by resistors. That said, if even I was able to make this work, then you should be able to as well!
Microcontroller: I used an ATTiny85 chip, which cost about 1 each.
Microcontroller Programmer: In order to get the code onto the chip, you need a way to program it. With regular arduino this is just a USB cable, but for the ATTiny chip, you need something extra. You can use another arduino to do this or, like me, you can use a Tiny AVR programmer from Sparkfun.
I would recommend this, as I’ve tried programming them with various methods and this one is the easiest. The board is a bit expensive, but a good investment if you do a lot of ATTiny projects.
8 Pin Chip Socket: If you put the chip in a socket rather than soldering it directly, you can afford yourself some mistakes in assembly. Spoken from experience - nobody wants to desolder chips to reprogram them.
Capacitor: A decoupling capacitor of 100nF (code 104) is used. I don’t understand quite why, but I read that decoupling capacitors are important on the internet, so it must be true…
Resistor: A 10k resistor is used to pull down the line into the arduino. Again, yet another mystery of electronics.
Perfboard/Stripboard: Some baseboard upon which to assemble your circuit.
Winding Wire: Regular sheathed wire is too thick to solder onto the motor. Using fine enamelled wire will reduce the stress on the motor terminals and make your life a lot easier.
Servo Wire: A three wire ribbon terminating in a 3-pin JR female plug. I got mine from a burnt out servo that I was ‘modifying’.
Stepper Motor: I used a 6mm bipolar Nidec stepper motor. Any small stepper should work, although keep them small, as the stepper is being driven directly from the Arduino.
Header Pins: Not essential, but if you wire your stepper to 4 header pins and put a socket on your circuit, you can easily unplug your dashboard for ease of installation.
Computer: To program your board, you’ll need a computer. Possibly with the Arduino IDE. And maybe a USB cable. If it has a power cable as well, then even better. “