ESP8266 might be the cheapest WiFi SoC for IoT application available, but it’s not really renowned for its power efficiency, and is often not considered the best choice for battery powered applications. This has not stopped Jeifa from developing a WiFi smartwatch based on the chip, and the 250 mAh battery used in the design is said to be good enough for 1 or 2 days of operation on a charge.

Main components of Jeija’s ESP8266 smartwatch:

SoC – Espressif ESP8266 with 32Mbit of flash memory

Display – SSD1306 OLED Display, 128×64 resolution

Connectivity – 802.11 b/g/n WiFi (via ESP8266)

Sensor – Invensense MPU-9250 gyroscope, accelerometer, and compass

Debugging / Programming – FT232RQ for USB communication

Misc RV-3029-C2 Real Time Clock with alarm function, and temperature sensor 3x user buttons Vibration Motor

Power 250mAh LiPo battery MCP73831 LiPo charger

Dimensions – 35 x 39 x 11mm (board)

He designed the PCB with Kicad, and the firmware is based on esp-open-sdk, with all hardware and software files released in github under respectively Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC-BY-NC-SA), and MIT licenses. Bear in mind that the project is mostly a hardware project, and the firmware is used to show the hardware works, so you may have to tweak the code to have the watch do what you want.

Jeija also shot a video showing how to solder the components and test the watch as you build it. Interestingly enough, he could not buy ESP8266-EX chip directly, so instead he bought ESP-01 module, and unsoldered the chip to solder it back on the watch PCB.

His other videos show how it can be used as a compass or game controller.

Via ESP8266COM Tweet