2 layers68 × 40 mm
Stm32-io extend
hardenedlinux/cheap-pcb
Cheap PCB: Better understanding the current status of hardware supply chain
44 parts170CC0-1.0
2 layers41 × 31 mm
STM32F103 microcontroller board designed in KiCad – schematic, PCB layout and fabrication files
- Size
- 41 × 31 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 32
- Nets
- 50
- Pads
- 132
- Tracks, vias
- 213, 25
- Pours
- 4
- Routed
- Yes
- KiCad
- KiCad 10.0 (file 20260206)
- Created
- 16 Oct 2026
- Updated
- 16 Oct 2026
Overview
STM32 is an open-source printed circuit board by micahpinto, from the micahpinto/stm32-dev-board repository on GitHub, published under the MIT licence. It is a 2-layer board of 41 × 31 mm with 32 parts on 50 nets, routed with 213 tracks and 25 vias.
It is built around the STM32F103C8T6 and AMS1117-3.3. Its parts include 13 capacitors, 5 resistors, 4 connectors, 2 ICs and 1 diode. It belongs with the microcontroller boards boards and the STM32 boards of this library.
Main components
2
STM32F103C8T6
LQFP-48(7x7)-40℃~+85℃ 12bit 20KB 2V~3.6V 32 Bit 37 64KB 72MHz ARM Cortex-M3 Built-in FLASH LQFP-48(7x7) Microcontrollers (MCU/MPU/SOC) ROHSSTMicroelectronicsMicrocontrollers (MCU/MPU/SOC)
AMS1117-3.3
SOT-223-40℃~+125℃ 0.003%Vout 1 1.1V@(800mA) 15V 1A 3.3V 5mA 72dB@(120Hz) Fixed Over Current Protection、Short Circuit Protection、Thermal shutdown Positive SOT-223 Voltage Regulators - Linear, Low Drop Out (LDO) Regulators ROHSAdvanced Monolithic SystemsVoltage Regulators - Linear, Low Drop Out (LDO) Regulators
README
README.mdSTM32 Development Board
A compact 2-layer development board based on the STM32F103C8T6 microcontroller, designed in KiCad. Designed during my Master's as a hands-on project in microcontroller hardware and PCB design.
Status: Hardware design complete.
Features
- MCU: STM32F103C8T6 (Arm Cortex-M3, 72 MHz, 64 KB Flash, 20 KB SRAM, LQFP48)
- USB: Micro-B connector for 5 V power and USB full-speed device (1.5 kΩ pull-up on D+)
- Power: AMS1117-3.3 LDO regulator (5 V USB input → 3.3 V)
- Clock: 16 MHz HSE crystal with 10 pF load capacitors
- Analog supply: VDDA filtered with a 120 Ω ferrite bead and decoupling capacitors
- Programming: SWD header (3V3, SWDIO, SWCLK, GND)
- Boot mode: BOOT0 slide switch to select the built-in bootloader
- Interfaces: UART and I2C headers (with 1.5 kΩ I2C pull-ups)
- Indicators: Red power LED
- Mechanical: 4 × M2 mounting holes
MCU Pinout
| Function | Pins |
|---|---|
| SWD | PA13 (SWDIO), PA14 (SWCLK) |
| HSE crystal | PD0 (OSC_IN), PD1 (OSC_OUT) |
| USB | PA11 (D−), PA12 (D+) |
| USART1 | PB6 (TX), PB7 (RX) |
| I2C2 | PB10 (SCL), PB11 (SDA) |
Schematic
PCB Layout
Design Process
- Pin planning: configured SWD, HSE crystal, USB, UART and I2C in STM32CubeMX
- Schematic: MCU with 100 nF decoupling per supply pin plus bulk capacitance, ferrite-bead filtered VDDA, crystal load capacitors calculated from the crystal's load capacitance and estimated stray capacitance, USB D+ pull-up, LDO with input/output capacitors, BOOT0 switch
- ERC: electrical rules check passed
- Footprint assignment: 0402/0603/0805 SMD passives, 3D model added for the USB connector
- PCB layout: 2-layer board, solid ground plane on the bottom layer, decoupling capacitors placed close to each supply pin, crystal and load capacitors placed close to the MCU
- Routing: USB D+/D− routed as a short differential pair, 0.3 mm signal traces, 0.5 mm power traces, ground vias and copper pours around the regulator
- DRC: design rules check passed against the manufacturer's capabilities
- Fabrication outputs: Gerber file, drill file, BOM and component placement file
Programming Interface
- SWD: connect an ST-Link to the SWD header for programming and debugging.
- Bootloader: set BOOT0 high, reconnect power, then flash. Set BOOT0 back low to run the program.
Repository Contents
| Folder | Contents |
|---|---|
Hardware/ | KiCad project, schematic, PCB and custom footprint library |
Firmware/stm32_pinout/ | STM32CubeMX pin configuration (stm32_pinout.ioc) |
Fabrication/ | Gerber files, drill file, BOM, placement file, schematic PDF |
images/ | Renders and screenshots |
Tools
- KiCad 6.0
- STM32CubeIDE / STM32CubeMX
References
- STM32F103C8 product page and datasheet
- ST AN2867: Oscillator design guide for STM32 MCUs
- ST AN4879: USB hardware and PCB guidelines using STM32 MCUs
Parts
32| Qty | Value | Footprint | References |
|---|---|---|---|
| 5 | 100n | Capacitor_SMD:C_0402_1005Metric | C1, C2, C3, C4, C8 |
| 4 | 1k5 | Resistor_SMD:R_0402_1005Metric | R2, R3, R4, R5 |
| 4 | MountingHole | MountingHole:MountingHole_2.2mm_M2 | H1, H2, H3, H4 |
| 3 | Conn_01x04_Pin | Connector_PinHeader_2.54mm:PinHeader_1x04_P2.54mm_Vertical | J2, J3, J4 |
| 2 | 10p | Capacitor_SMD:C_0402_1005Metric | C9, C10 |
| 2 | 1µ | Capacitor_SMD:C_0402_1005Metric | C6, C7 |
| 2 | 22µ | Capacitor_SMD:C_0805_2012Metric | C11, C12 |
| 1 | 10k | Resistor_SMD:R_0402_1005Metric | R1 |
| 1 | 10n | Capacitor_SMD:C_0402_1005Metric | C5 |
| 1 | 10µ | Capacitor_SMD:C_0603_1608Metric | C13 |
| 1 | 120R | Inductor_SMD:L_0603_1608Metric | FB1 |
| 1 | 16MHz | Crystal:Crystal_SMD_3225-4Pin_3.2x2.5mm | Y1 |
| 1 | AMS1117-3.3 | Package_TO_SOT_SMD:SOT-223-3_TabPin2 | U2 |
| 1 | RED | LED_SMD:LED_0603_1608Metric | D1 |
| 1 | STM32F103C8T6 | Package_QFP:LQFP-48_7x7mm_P0.5mm | U1 |
| 1 | SW_SPDT | Library:SW_SPDT_PCM12 | SW1 |
| 1 | USB_B_Micro | Connector_USB:USB_Micro-B_Wuerth_629105150521 | J1 |
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Questions
How big is the STM32 PCB?
It measures 41 × 31 mm and has 2 copper layers, 1.6 mm thick.
What parts does the STM32 use?
32 parts, built around the STM32F103C8T6 and AMS1117-3.3. 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 STM32 KiCad files?
From the micahpinto/stm32-dev-board repository on GitHub, at the commit this page was made from: the board is Hardware/STM32.kicad_pcb and its schematic Hardware/STM32.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the STM32 design in my own project?
Its repository publishes it under the MIT licence: you may reuse it on that licence's terms (keep the author's notice, and for a copyleft licence share your changes alike).