This is the code for a digital speedometer I built for one of my motorcycles. The motivation is to have a customizable speedometer made with cheap and readily available components, with clear instructions on how to implement it for anyone else's own applications. Also I wanted to improve my C/C++ and get better at electronics.
This project was developed mostly using the excellet Wokwi, a web based arduino emulator and IDE. Click here to see an emulation of it working, and mess around with it over there. To get this working on actual hardware, you will need the Arduino IDE and a compatible micro controller with the necessary hardware assembled. Once you have that, clone this repo into your Arduino folder, open the project, and upload the code to your device. That is a simplified overview, but I am happy to advise if you are interested in building one of these.
Main components:
- Arduino Nano
- KY-040 Rotary Encoder module
- KY-003 Hall Effect Sensor Module
- HD44780 20x4 lcd display with I2C control board
- Mini360 power module
Others:
- Perf board, 81mm by 51mm (I used this one)
- Jumper wires
- Neodymium magnet
- button head screws - M2, M3
- countersunk screws - M3, M4
- Heat set inserts - M3 and M4
Printable parts:
Things that will be nice to have on hand:
- Cat5 cable
- An old wiring harness - for scavenging wire.
- RTV silicone and/or Liquid electrical tape - for sealing enclosures and potting circuit boards.
- VHB tape (I used this to mount the hall sensor)
All you need to do is turn your bike on, and this device shows your speed in arabic numerals on the screen as you ride. Units of measure can be selected using the jogwheel, and a 0-60 timer is also included just for fun. To use the 0-60 timer, come to a stop, press the jogdial button and take off. The first reading of the hall effect sensor will start the timer, and when the timer sees 60 (km/h or mph) it will stop and show your time, until you push the jog dial button again.
This project relies on a few external arduino libraries. Shoutout to everyone involved in those. Arduino.h - the arduino core library. LiquidCrystal_I2C - a library that handles communication with HD44780 displays via I2C. LCDBigNumbers - an awesome library that lets you put big numerical digits on hd44780 displays.