An ATTiny404 LED Xmas tree ornament. I made a bunch of these as gifts.
Schematic, in case I don't feel like opening KiCad:
- svg2mod was used to generate the footprint of the board, and the front silkscreen layer
- The Tree Emoji u1f332 SVG was modified so I could create a footprint from it.
- I referred to SerialUPDI to figure out UPDI, but made my own board for adapting between FTDI and UPDI (and left a typo in the name, oops)
- megaTinyCore was used with Arduino (via the vscode Arduino extension) to upload to the ATTiny404
| Reference | Description |
|---|---|
| PCB | $0.43 (+ $0.40 shipping) per PCB |
| C1 | 1 uf 1206 capacitor |
| D1 - D7 | 1206 Bidirectional Red/Green LED |
| R1 - R7 | 1206 50 ohm resistor |
| SW1 | 6x6mm Pushbutton |
| SW2 | JS102011SAQN Slide Switch |
| U1 | Attiny404-SS |
| B1 | CR2023 Battery Holder |
In 2021 I made the snowflake-ornament, which was a different design that ran on the ATTiny85. This year I wanted something with a bit more I/O, and it also helps that the ATTiny404 was almost a whole $1 cheaper per unit than the ATTiny85.
Since I had more I/O, I could also fit more LEDs on the board. Instead of only 6 LEDs from last year, this year's design has 7 bi-directional red/green LEDs. (The ATTiny404 has 6 PWM pins, I wanted PWM on each LED but the design looked weird with only 6.)
One downside of this is that I couldn't use the same programming interfaces that I've used for other boards, but I made my own FTDI to UPDI adapter to handle it.
To connect to the board, instead of leaving an unpopulated programming header, I left some test points and used a spring-loaded pogo pin jig:
Another important change from last year was to use 1206 components everywhere. Last year I used 0603 LEDs, the bigger components were much easier to assemble.
Last year I spent a lot of time optimizing the ornament to run in deep sleep mode when not in use, so I could just use a single button to power it on and change patterns. That was a lot of work, and by the next year the batteries would be dead. This year, I instead just used an on/off switch.