4 layers26 × 30 mm
2 layers28.6 × 49.8 mm
The 1N5819 Schottky diode provides OR-ing between USB and VIN — whichever is higher wins automatically. Forward drop is 0.4V.
- Size
- 28.6 × 49.8 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 29
- Nets
- 27
- Pads
- 127
- Tracks, vias
- 223, 27
- Pours
- 2
- Routed
- Yes
- KiCad
- KiCad 10.0 (file 20260206)
- Created
- 17 May 2026
- Updated
- 17 May 2026
Overview
ESPQT is an open-source printed circuit board by Computationgeek, from the Computationgeek/PEBBLEC3 repository on GitHub. It is a 2-layer board of 28.6 × 49.8 mm with 29 parts on 27 nets, routed with 223 tracks and 27 vias.
It is built around the ESP32-C3 and AP2112K-3.3. Its parts include 6 resistors, 4 capacitors, 4 connectors, 3 diodes and 2 ICs. It belongs with the ESP32 and RISC-V boards of this library.
Main components
2README
README.md🍊 FruitWorks PebbleC3
Built by makers, for makers.
PebbleC3 is a compact, open-source ESP32-C3 development board designed by FruitWorks Electronics. Built as a portfolio and KiCad skill project, it packs native USB, Qwiic/STEMMA QT connectivity, and castellated edges into a small, orange form factor.
✨ Features
- ESP32-C3-WROOM-02 — RISC-V single-core @ 160MHz, 4MB Flash, 400KB SRAM, Wi-Fi + BLE 5.0
- Native USB — Direct USB-C to ESP32-C3 USB (no CH340 or CP2102), supports CDC/JTAG
- AP2112K-3.3 LDO — 600mA, ultra-low dropout (350mV), SOT-23-5
- Qwiic / STEMMA QT — JST-SH 4-pin connector for plug-and-play I2C ecosystem
- Castellated edges — 8-pin castellated pads on each side, 2.54mm pitch, solderable directly to a carrier board
- User LED + Power LED — GPIO-driven user LED (IO3) and always-on power indicator
- Boot + Reset buttons — Standard tactile switches for programming and reset
- Test points — VOUT and GND test pads for bench probing
- Open Source Hardware — Full KiCad project, schematics, and Gerbers available
📐 Specifications
| Parameter | Value |
|---|---|
| MCU | ESP32-C3-WROOM-02 |
| Clock Speed | 160 MHz |
| Flash | 4MB |
| SRAM | 400KB |
| Connectivity | Wi-Fi 802.11 b/g/n + BLE 5.0 |
| USB | USB-C, Native USB 2.0 (CDC + JTAG) |
| Operating Voltage | 3.3V |
| Input Voltage (VIN) | 3.8V – 6V |
| Input Voltage (USB) | 5V |
| LDO Output Current | 600mA max |
| I2C | IO8 (SDA), IO10 (SCL) |
| PCB Layers | 2 |
| PCB Dimensions | ~52 x 36mm |
| PCB Color | Ember Orange |
| Finish | ENIG |
📌 Pinout
Left Edge (J4)
| Pin | Signal | Notes |
|---|---|---|
| 1 | GND | Ground |
| 2 | 3V3 | 3.3V regulated output |
| 3 | IO4 | GPIO / ADC |
| 4 | IO5 | GPIO / ADC |
| 5 | IO6 | GPIO |
| 6 | IO7 | GPIO |
| 7 | IO8/SDA | GPIO / I2C Data |
| 8 | BOOT | GPIO9, Boot button net |
Right Edge (J3)
| Pin | Signal | Notes |
|---|---|---|
| 1 | VIN | Raw voltage input (3.8–6V) |
| 2 | GND | Ground |
| 3 | IO0 | GPIO / ADC |
| 4 | IO1 | GPIO / ADC |
| 5 | IO2 | GPIO / ADC, strapping pin |
| 6 | IO10/SCL | GPIO / I2C Clock |
| 7 | RXD | UART RX (IO20) |
| 8 | TXD | UART TX (IO21) |
Qwiic / STEMMA QT (J2)
| Pin | Signal |
|---|---|
| 1 | GND |
| 2 | 3.3V |
| 3 | SDA (IO8) |
| 4 | SCL (IO10) |
🧩 Bill of Materials
| Reference | Qty | Value | Footprint | Datasheet |
|---|---|---|---|---|
| C1, C2 | 2 | 1µF | C_0805_2012Metric | — |
| C3 | 1 | 100nF | C_0201_0603Metric | — |
| C4 | 1 | 10µF | C_0805_2012Metric | — |
| D1 | 1 | User LED | LED_0805_2012Metric | — |
| D2 | 1 | Power LED | LED_0805_2012Metric | — |
| D4 | 1 | 1N5819 (SOD-123W) | Nexperia_CFP3_SOD-123W | Datasheet |
| J1 | 1 | USB-C 16P Receptacle | USB_C_Receptacle_GCT_USB4110 | USB Spec |
| J2 | 1 | Qwiic / STEMMA QT | JST_SH_BM04B-SRSS-TB_1x04-1MP | — |
| J3 | 1 | Right Castellated Edge (8-pin) | PinHeader_1x08_P2.54mm | — |
| J4 | 1 | Left Castellated Edge (8-pin) | PinHeader_1x08_P2.54mm | — |
| R1, R2 | 2 | 5.1kΩ | R_0805_2012Metric | — |
| R3, R6 | 2 | 470Ω | R_0805_2012Metric | — |
| R4, R5 | 2 | 10kΩ | R_0805_2012Metric | — |
| SW1 | 1 | Reset Button | SW_SPST_TS-1088 | — |
| SW2 | 1 | Boot Button | SW_SPST_TS-1088 | — |
| TP1 | 1 | VOUT Test Point | TestPoint_Pad_D1.0mm | — |
| TP2 | 1 | GND Test Point | TestPoint_Pad_D1.0mm | — |
| U1 | 1 | ESP32-C3-WROOM-02 | ESP32-C3-WROOM-02 | Datasheet |
| U2 | 1 | AP2112K-3.3 | SOT-23-5 | Datasheet |
⚡ Power
PebbleC3 can be powered two ways:
Via USB-C — 5V from USB → 1N5819 diode → AP2112K-3.3 LDO → 3.3V rail
Via VIN pad — 3.8V–6V on VIN castellation → 1N5819 → LDO → 3.3V rail
The 1N5819 Schottky diode provides OR-ing between USB and VIN — whichever is higher wins automatically. Forward drop is ~0.4V.
⚠️ Do not exceed 6V on VIN. AP2112K-3.3 absolute maximum input is 6V.
🔌 USB and Programming
PebbleC3 uses the ESP32-C3's native USB peripheral directly — no USB-to-UART bridge chip needed.
To flash firmware:
- Hold BOOT button
- Press and release RESET
- Release BOOT
- Flash using
esptool.pyor Arduino IDE
Arduino IDE board selection:
Board: ESP32C3 Dev Module
Upload Speed: 921600
USB CDC On Boot: Enabled🏭 Manufacturing
Designed for JLCPCB 2-layer standard process.
| Setting | Value |
|---|---|
| Layers | 2 |
| Thickness | 1.6mm |
| Surface Finish | ENIG |
| Solder Mask | Orange |
| Silkscreen | White |
| Castellated Holes | Yes |
| Min Hole Size | 0.2mm |
| Min Clearance | 0.1mm |
When ordering, select "Castellated holes: Yes" — without this JLCPCB will route through your castellation pads.
🔓 License
This project is Open Source Hardware licensed under the CERN-OHL-P v2.
You are free to use, modify, and manufacture this design. Attribution to FruitWorks Electronics appreciated.
Built by makers, for makers.
Parts
29| Qty | Value | Footprint | References |
|---|---|---|---|
| 2 | 10K | Resistor_SMD:R_0805_2012Metric | R4, R5 |
| 2 | 1uF | Capacitor_SMD:C_0805_2012Metric | C1, C2 |
| 2 | 470 | Resistor_SMD:R_0805_2012Metric | R3, R6 |
| 2 | 5.1K | Resistor_SMD:R_0805_2012Metric | R1, R2 |
| 2 | LOGO | LOGO | G***, G*** |
| 1 | 100nF | Capacitor_SMD:C_0201_0603Metric | C3 |
| 1 | 10uF | Capacitor_SMD:C_0805_2012Metric | C4 |
| 1 | 1N5819 | Diode_SMD:Nexperia_CFP3_SOD-123W | D4 |
| 1 | 3V3 | TestPoint:TestPoint_Pad_D1.0mm | TP1 |
| 1 | AP2112K | Package_TO_SOT_SMD:SOT-23-5 | U2 |
| 1 | BOOT | Button_Switch_SMD:SW_SPST_TS-1088-xR020 | SW2 |
| 1 | ESP32-C3 | RF_Module:ESP32-C3-WROOM-02 | U1 |
| 1 | GND | TestPoint:TestPoint_Pad_D1.0mm | TP2 |
| 1 | Left_Edge | Connector_PinHeader_2.54mm:PinHeader_1x08_P2.54mm_Vertical_Mod | J4 |
| 1 | PWRLED | LED_SMD:LED_0805_2012Metric | D2 |
| 1 | QWIIC | Connector_JST:JST_SH_BM04B-SRSS-TB_1x04-1MP_P1.00mm_Vertical | J2 |
| 1 | RESET | Button_Switch_SMD:SW_SPST_TS-1088-xR020 | SW1 |
| 1 | Right_Edges | Connector_PinHeader_2.54mm:PinHeader_1x08_P2.54mm_Vertical_Mod | J3 |
| 1 | USB2.0_C_16P | Connector_USB:USB_C_Receptacle_GCT_USB4110 | J1 |
| 1 | USERLED | LED_SMD:LED_0805_2012Metric | D1 |
The 25 most common of 29 parts.
Questions
How big is the ESPQT PCB?
It measures 28.6 × 49.8 mm and has 2 copper layers, 1.6 mm thick.
What parts does the ESPQT use?
29 parts, built around the ESP32-C3 and AP2112K-3.3. 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 ESPQT KiCad files?
From the Computationgeek/PEBBLEC3 repository on GitHub, at the commit this page was made from: the board is ESPQT.kicad_pcb and its schematic ESPQT.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the ESPQT design in my own project?
Its repository states no licence, so its author keeps all rights: ask Computationgeek before reusing the design.
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