Ever since seeing smart watches and other devices that use OLED displays I have been interested in making my own board that I can use for different projects. I have a couple in mind…..a Smart Watch and an upgrade to my previous project from 4 years ago an OBDII Gas gauge which can be found here.
Based on what I wanted, below were my requirements:
- Small as possible. Ideally no bigger than the OLED display.
- Integrated OLED display.
- Programmed via micro USB
- Compatible with the Arduino IDE
- Low power consumption
- Can be run off coin cell or lipo battery
- Lipo battery charged via USB
A lot of the inspiration for this project came from the excellent work done by Zak Kemble at his blog.
I took some of his design and modified it for my use. His design was specifically designed to be a watch and I wanted something more generic that I could use for multiple different projects. I split his design into multiple boards. FYI – His design and code is excellent and if you need to start electronics design
I can tell you I did go through many iterations of the design and all I am going to do here is show the final design, my decisions and some of the issues I had in retrospect.
Below is the final result and here are the specs:
CPU: Atmega32u4. Configured to 8Mhz internal oscillator
Display: SSD1306 1.3″ OLED (Blue or White)
RTC: DS3231M (rather expensive, but very accurate chip)
BootLoader: Catalina (looks like a Leonardo in Arduino IDE)
Power: Micro USB, or additiional LIPO board that charges via USB. I also have a coincell board using CR2032 but not sure how long that would last.
Dimensions: 35.5mm x 23.0mm x 6.23mm (max thickness at USB connector. OLED+ board is only 3.33mm)
Connector: Board To Board mezzanine connector
Part 2 will details the schematic and the Lipo board.