“A tamagotchi-like toy with an OLED display and Li-Po battery.
This is a little tamagotchi-like toy I’ve created for my wife. I used to think that this is how a modern Tamagotchi could look like initially. However, it can also be used as a battery-powered DIY platform to experiment with FreeRTOS and graphics.
Specifications
- 35x47mm board
- Monochrome OLED 128x64px
- Low energy consumption (~20mA @ active, 0.75mA @ sleep)
- Hand-soldering friendly (TQFP-44 0.8mm pitch, smallest is 0603)
- 3D-printable case
- Open Source Hardware/Firmware
Hardware
- ATmega1284P 8-bit AVR MCU with 128 KiB flash and 16 KiB SRAM
- SH1106G display controller
- MCP73831 charge controller
- AP3401 DC-DC buck converter
- 400mAh 3.7V Li-Po battery (~26h @ active, ~30 days @ sleep)
- Load-sharing circuit (can be powered by USB or battery, like a smartphone)
- KiCad 5.1.0 project for schematic and board designs
- Released under CERN-OHL-W v2 (Rev. 4) and CC-BY-SA (before Rev. 4)
Software
Please, note that the software part of the project isn’t finished yet!
- Shows a frame time, energy left and a battery charged status
- Animation with Exy-in-the-bottle, a “personal daemon”
- Programmed in C99 using the FreeRTOS kernel modified for ATmega1284P
- There are three tasks only: Display, Battery Monitor and Sleep Mode
- Released under GNU GPLv3+”