The OLED Watch project was inspired by smartwatches, such as the Pebble. In an attempt to recreate and design a custom build, I compiled some of my smaller projects to put together an OLED Watch.
I wrote a report for this project and posted it on GitHub.
The OLED Display is a 1.3" monochrome display from Adafruit. It can communicate with a microcontroller through I2C or SPI, but I decided to use I2C to minimize the wiring.
The Real-Time Clock module is a custom breakout board using the DS1307 RTC chip. The module includes pull-up resistors for I2C communication with a microcontroller and a 2032 coin battery to keep track of time even when not connected to a microcontroller.
The ATmega328p module is a breakout board for the ATmega328p AVR microcontroller with a 16 MHz resonator, 5V LDO (voltage regulator), and headers that allow easy access to the I/O and power pins of the microcontroller.
For the first prototyping of the project, two 2032 coin batteries, rated at 3V, were used in series to optain 6V. All the same, The voltage would drop below 5.5V as the batteries started wearing out, causing issues with the OLED display. Thus, the coin battery setup was soon replaced by a custom LiPo Control board module. The LiPo Control board includes a charging circuit for a single-cell LiPo battery and a switching regulator circuit to boost the 3.7V of the single-cell LiPo to 5V. The charging circuit uses a MCP73831 while the switching regulator features a TPS61200. The board has a micro-usb port which can be used to power the charging circuit.
Using female-to-female jumper wires, the modules were connected without much additional effort, and the OLED Watch could be easily set up on the wrist.
Printed Circuit Board
After testing the design, I proceeded to capture the schematic on EAGLE and layout a single-board design.
I decided to stop the production of this model and proceed to a new design upgrading the microcontroller to one with embedded bluetooth capabilities. A microcontroller with embedded bluetooth would allow for the OLED Watch to be a smartwatch and would reduce the size of circuitry since aditional circuitry for bluetooth wouldn't be necessary.
Bluetooth only module solutions:
- CC2540 (Texas Instruments)
- nRF51822 (Nordic Semiconductors)
- nRF8001 (Nordic Semiconductors)
SoC modules with microcontrollers and embedded bluetooth solution:
- RFduino (ARM M0) (Arduino compatible)
- nRF51822 (ARM M0)
In addition, I have designed OLED display breakout boards after the development of this project, so I could integrate that circuitry into the OLED Watch single-board and acquire an OLED Display straight from the manufacturers, not from Adafruit, and reduce cost and unnecessary circuitry that the Adafruit module includes but my design does not require.
Furthermore, the current design does not include any onboard switches or buttons. I would like to include a few inputs for user interaction. Nevertheless, I'm also considering other input types, such as gyroscopes, accelerometers, touch screens, or touchless-inputs (infrared phototransistors).