2 layers80 × 33.5 mm
Tomogatchicarrieronly
chimmmmy/echain
software to control a smart keychain with an e ink display, powered by seed studio nrf52840
5 parts1GPL-3.0
2 layers80 × 33.5 mm
Tomogatchi
chimmmmy/echain1software to control a smart keychain with an e ink display, powered by seed studio nrf52840
- Size
- 80 × 33.5 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 25
- Nets
- 28
- Pads
- 95
- Tracks, vias
- 219, 100
- Pours
- 2
- Routed
- Yes
- KiCad
- KiCad 9.0 (file 20241229)
- Created
- 3 Mar 2026
- Updated
- 12 Mar 2026
Overview
Tomogatchi is an open-source printed circuit board by chimmmmy, from the chimmmmy/echain repository on GitHub, published under the GPL-3.0 licence. It is a 2-layer board of 80 × 33.5 mm with 25 parts on 28 nets, routed with 219 tracks and 100 vias.
It is built around the B0540W and SI1304BDL. Its parts include 13 capacitors, 3 diodes, 2 resistors, 1 transistor and 1 connector. It belongs with the lEDs and displays boards of this library.
Main components
2README
README.mdechain
a smart keychain with an e ink display, powered by seed studio nrf52840
objectives
-
show a smart pet on the front that can be interacted with via the two buttons on the back of the device
-
show music and notifications from phone by using bluetooth
-
off screen should show a customizable image that can be sent to the device over bluetooth
-
battery should last at LEAST a month
-
utilize the nrf52480's deep sleep function to increase battery life
-
prototypes out of plastic, final out of cnc aluminum
current capabilities (untested)
-
show a basic landscape display
-
connect to an android phone via bluetooth
-
change off screen via bluetooth
-
show music currently being played via bluetooth
-
interactable via 2 buttons
-
able to enter deep sleep and exit deep sleep
Parts
25| Qty | Value | Footprint | References |
|---|---|---|---|
| 10 | 1uF | epaperIO:C0603 | C1, C2, C3, C7, C8, C9, C10, C11, C12, C13 |
| 3 | B0540W | epaperIO:SOD-323 | D1, D2, D3 |
| 1 | 0.47R/1% | epaperIO:R0603 | R3 |
| 1 | 100nF | epaperIO:C0603 | C6 |
| 1 | 10K | epaperIO:R0603 | R4 |
| 1 | 10uH | epaperIO:L0420 | L1 |
| 1 | 220uF/6.3V | epaperIO:AVX-B | C4 |
| 1 | 4.7uF/50V | epaperIO:C1206 | C5 |
| 1 | BTN_A | Button_Switch_SMD:SW_SPST_CK_RS282G05A3 | BTNA1 |
| 1 | BTN_B | Button_Switch_SMD:SW_SPST_CK_RS282G05A3 | BTNB1 |
| 1 | Display | epaperIO:FPCB24-SMD-0.5-17.6X5.0X2MM | J2 |
| 1 | Si1304BDL | epaperIO:SOT-323 | Q1 |
The 23 most common of 25 parts.
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Questions
How big is the Tomogatchi PCB?
It measures 80 × 33.5 mm and has 2 copper layers, 1.6 mm thick.
What parts does the Tomogatchi use?
25 parts, built around the B0540W and SI1304BDL. The full list of its parts is on this page, with links to each part's symbol and footprint where PCBKit's library has them.
Where can I download the Tomogatchi KiCad files?
From the chimmmmy/echain repository on GitHub, at the commit this page was made from: the board is tomogatchi/tomogatchi.kicad_pcb and its schematic tomogatchi/tomogatchi.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the Tomogatchi design in my own project?
Its repository publishes it under the GPL-3.0 licence: you may reuse it on that licence's terms (keep the author's notice, and for a copyleft licence share your changes alike).