2 layers100.5 × 79.9 mm
2 layers110.3 × 33.1 mm
Arcane
cloudglides/ara1An easy-to-replicate watch built around the STM32.
- Size
- 110.3 × 33.1 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 42
- Nets
- 34
- Pads
- 129
- Tracks, vias
- 198, 36
- Pours
- 1
- Routed
- Yes
- KiCad
- KiCad 10.0 (file 20260206)
- Created
- 19 Mar 2026
- Updated
- 11 May 2026
Overview
Arcane is an open-source printed circuit board by cloudglides, from the cloudglides/ara repository on GitHub. It is a 2-layer board of 110.3 × 33.1 mm with 42 parts on 34 nets, routed with 198 tracks and 36 vias.
It is built around the STM32L031F6P6 and XC6220B331MR. Its parts include 11 capacitors, 6 resistors, 4 connectors, 3 ICs and 2 diodes. It belongs with the wearables boards and the STM32 boards of this library.
Main components
2
STM32L031F6P6
TSSOP-20-40℃~+85℃ 1.8V~3.6V 12bit 15 1KB 32 Bit 32KB 32MHz 8KB ARM Cortex-M0+ Built-in FLASH TSSOP-20 Microcontrollers (MCU/MPU/SOC) ROHSSTMicroelectronicsMicrocontrollers (MCU/MPU/SOC)
XC6220B331MR
SOT-23-5-40℃~+85℃@(Ta) 1 25uA 3.3V 400mV@(800mA) 5.5V 50dB@(10kHz) 900mA Fixed Over Current Protection、Over Temperature Protection Positive SOT-23-5 Voltage Regulators - Linear, Low Drop Out (LDO) Regulators ROHSTECH PUBLICVoltage Regulators - Linear, Low Drop Out (LDO) Regulators
README
README.md
Ara
Open Time. Open Source.
Key Features • PCB • Credits
Ara is a custom watch PCB built around STM32, and LiPo charging into a 2 layer manufacturable board. Built because most smartwatches don't let you know whats inside. Ara is designed from scratch open source and exactly what's needed.
To build your own, grab the KiCad files, review the schematic below, and send the panelized design to your preferred PCB fab. Flash your firmware over STM32 HEADER PINS and you're good to go.
Every smartwatch on the market is firmware locked. Ara exists to change that.
Key Features
- STM32 microcontroller which can go into ultra low power mode
- Battery charging with Integrated IC and solder pad for 1S LiPo
- Multiple Status LEDs for visual feedback
- USB-C connectivity
- Panelized design for cost-effective manufacturing
PCB
Designed in KiCad with attention to power management, and IC integration. The board features a 2-layer optimized routing.
Schematic
PCB Layers
Layer 1
Layer 2
Board Views
Front
Back
Zine
Credits
This project uses:
- KiCad
- Blender for renders
- Hack Club Fallout
License
GPL
Parts
42| Qty | Value | Footprint | References |
|---|---|---|---|
| 8 | MountingHole | MountingHole:MountingHole_2.2mm_M2 | H1, H1, H2, H2, H3, H3, H4, H4 |
| 4 | TestPoint | TestPoint:TestPoint_Pad_1.0x1.0mm | TP1, TP2, TP3, TP4 |
| 3 | 100nf | Capacitor_SMD:C_0603_1608Metric_Pad1.08x0.95mm_HandSolder | C2, C11, C13 |
| 3 | 4.7uf | Capacitor_SMD:C_0603_1608Metric_Pad1.08x0.95mm_HandSolder | C1, C3, C4 |
| 2 | 10K | Resistor_SMD:R_0603_1608Metric_Pad0.98x0.95mm_HandSolder | R5, R6 |
| 2 | 10uf | Capacitor_SMD:C_0603_1608Metric_Pad1.08x0.95mm_HandSolder | C5, C8 |
| 2 | 22pf | Capacitor_SMD:C_0402_1005Metric_Pad0.74x0.62mm_HandSolder | C7, C9 |
| 2 | 5.1K | Resistor_SMD:R_0603_1608Metric_Pad0.98x0.95mm_HandSolder | R1, R2 |
| 2 | SW_Push | Button_Switch_SMD:SW_SPST_TL3342 | SW2, SW3 |
| 1 | 100uf | Capacitor_SMD:C_0603_1608Metric_Pad1.08x0.95mm_HandSolder | C10 |
| 1 | 2K | Resistor_SMD:R_0603_1608Metric_Pad0.98x0.95mm_HandSolder | R3 |
| 1 | 470E | Resistor_SMD:R_0603_1608Metric_Pad0.98x0.95mm_HandSolder | R4 |
| 1 | 5V | Diode_SMD:D_SOD-123 | D1 |
| 1 | Conn_01x02 | Connector_JST:JST_XH_S2B-XH-A_1x02_P2.50mm_Horizontal | J3 |
| 1 | Conn_01x06 | Connector_PinHeader_2.54mm:PinHeader_1x06_P2.54mm_Vertical | J4 |
| 1 | Conn_01x07 | Connector_PinHeader_2.54mm:PinHeader_1x07_P2.54mm_Vertical | J2 |
| 1 | Crystal | Crystal:Crystal_SMD_3215-2Pin_3.2x1.5mm | Y1 |
| 1 | LED | LED_SMD:LED_0402_1005Metric_Pad0.77x0.64mm_HandSolder | D2 |
| 1 | MCP73831-2-OT | Package_TO_SOT_SMD:SOT-23-5 | U2 |
| 1 | Polyfuse | Fuse:Fuse_0805_2012Metric_Pad1.15x1.40mm_HandSolder | F1 |
| 1 | STM32L031F6P6 | STM32:SOP65P640X120-20N | U3 |
| 1 | USB_C_Receptacle_USB2.0_16P | Connector_USB:USB_C_Receptacle_HRO_TYPE-C-31-M-12 | J1 |
| 1 | XC6220B331MR | Package_TO_SOT_SMD:SOT-23-5 | U1 |
Questions
How big is the Arcane PCB?
It measures 110.3 × 33.1 mm and has 2 copper layers, 1.6 mm thick.
What parts does the Arcane use?
42 parts, built around the STM32L031F6P6 and XC6220B331MR. 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 Arcane KiCad files?
From the cloudglides/ara repository on GitHub, at the commit this page was made from: the board is hardware/arcane.kicad_pcb and its schematic hardware/arcane.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the Arcane design in my own project?
Its repository states no licence, so its author keeps all rights: ask cloudglides before reusing the design.
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