2 layers83.3 × 65.3 mm
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46 parts14kMIT
2 layers90 × 135.4 mm
Stepper sc
smooker/cspcbclaude@smooker pcb creation
- Size
- 90 × 135.4 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 24
- Nets
- 42
- Pads
- 91
- Tracks, vias
- 0, 0
- Routed
- Not yet
- KiCad
- KiCad 9.0 (file 20241229)
- Created
- 7 Mar 2026
- Updated
- 18 Mar 2026
Overview
Stepper sc is an open-source printed circuit board by smooker, from the smooker/cspcb repository on GitHub. It is a 2-layer board of 90 × 135.4 mm with 24 parts on 42 nets.
It is built around the BC547. Its parts include 12 connectors, 5 capacitors, 4 resistors, 2 transistors and 1 IC. It belongs with the robots and motor control boards of this library.
Main components
1README
README.mdstepper_sc — STM32F411 Stepper Controller PCB
Single-axis stepper motor controller board built around the WeAct STM32F411CEU6 Black Pill v3.1.
Drives a CWD556 opto-isolated stepper driver (PUL/DIR interface) from MCU outputs via NPN buffer stage.
Block Diagram
24V ──── 78M05 ──── +5V ──── Black Pill (3.3V regulator on-board)
│
PB10 ─── R1/R2/Q1 ─── J2 (PUL → CWD556)
PB14 ─── R3/R4/Q2 ─── J3 (DIR → CWD556)
PA3 ─── J4 (Endstop L)
PA4 ─── J5 (Endstop R)
PA6 ─── J6 (Jog L)
PA7 ─── J7 (Jog R)
PB0 ─── J8 (Step L)
PB1 ─── J9 (Step R)
PB15 ─── J10 (Buzzer)Hardware
| Ref | Value | Function |
|---|---|---|
| U1 | 78M05 | 24V → 5V regulator |
| Q1, Q2 | BC547 | NPN buffer (PUL, DIR) |
| R1, R3 | 1kΩ | Base resistor |
| R2, R4 | 10kΩ | Base pull-down |
| C1 | 47µF | Regulator input bulk |
| C2, C4 | 100nF | Regulator decoupling |
| C3 | 100µF | Regulator output bulk |
| C5 | 100nF | Black Pill VIN decoupling |
| J1 | 2-pin screw | 24V power input |
| J2 | 2-pin screw | PUL output to CWD556 |
| J3 | 2-pin screw | DIR output to CWD556 |
| J4–J10 | 2-pin screw | Signal terminals |
| J11A, J11B | 1×20 header | Black Pill socket |
Pipeline
Schematic and netlist are generated from firmware source — main.h is the single source of truth for MCU pin assignments.
firmware/Core/Inc/main.h
│
▼ fw_to_net.py
howto_sch_and_then_api/stepper_sc.net
│
▼ howto_sch_and_then_api/stepper_sc_gen.py
stepper_sc/stepper_sc.kicad_schRe-generating after pin changes
# Activate venv (needs kicad-sch-api)
source venv/bin/activate
# Step 1: netlist from firmware
python3 fw_to_net.py
# Step 2: schematic from netlist
python3 howto_sch_and_then_api/stepper_sc_gen.pySetup
python3 -m venv venv
venv/bin/pip install kicad-sch-api
# KiCad symbol libraries — set path to your KiCad install
# e.g. /usr/share/kicad/symbols
ln -s /path/to/kicad/symbols kicad_symFirmware
See firmware/ for STM32 application source (Core/).
Requires ST HAL (Drivers/) — generate via STM32CubeMX or download from st.com.
Build:
cd firmware && makeFlash via Black Magic Probe:
arm-none-eabi-gdb -x script2.gdb build/stepper.elfSee doc/build-and-debug.md for full build, flash and debug instructions.
Parts
24| Qty | Value | Footprint | References |
|---|---|---|---|
| 3 | 100nF | Capacitor_SMD:C_0805_2012Metric | C2, C4, C5 |
| 2 | 10k | Resistor_SMD:R_0805_2012Metric | R2, R4 |
| 2 | 1k | Resistor_SMD:R_0805_2012Metric | R1, R3 |
| 2 | BC547 | Package_TO_SOT_SMD:SOT-23 | Q1, Q2 |
| 1 | 100uF | Capacitor_SMD:CP_Elec_8x6.2 | C3 |
| 1 | 47uF | Capacitor_SMD:CP_Elec_8x6.2 | C1 |
| 1 | 78M05 | Package_TO_SOT_SMD:TO-252-2 | U1 |
| 1 | BUZZ | TerminalBlock_RND:TerminalBlock_RND_205-00232_1x02_P5.08mm_Horizontal | J10 |
| 1 | Black_Pill_back | Connector_PinHeader_2.54mm:PinHeader_1x20_P2.54mm_Vertical | J12 |
| 1 | Black_Pill_front | Connector_PinHeader_2.54mm:PinHeader_1x20_P2.54mm_Vertical | J11 |
| 1 | DIR | TerminalBlock_RND:TerminalBlock_RND_205-00232_1x02_P5.08mm_Horizontal | J3 |
| 1 | ES_L | TerminalBlock_RND:TerminalBlock_RND_205-00232_1x02_P5.08mm_Horizontal | J4 |
| 1 | ES_R | TerminalBlock_RND:TerminalBlock_RND_205-00232_1x02_P5.08mm_Horizontal | J5 |
| 1 | JOGL | TerminalBlock_RND:TerminalBlock_RND_205-00232_1x02_P5.08mm_Horizontal | J6 |
| 1 | JOGR | TerminalBlock_RND:TerminalBlock_RND_205-00232_1x02_P5.08mm_Horizontal | J7 |
| 1 | PUL | TerminalBlock_RND:TerminalBlock_RND_205-00232_1x02_P5.08mm_Horizontal | J2 |
| 1 | PWR_24V | TerminalBlock_RND:TerminalBlock_RND_205-00232_1x02_P5.08mm_Horizontal | J1 |
| 1 | STEPL | TerminalBlock_RND:TerminalBlock_RND_205-00232_1x02_P5.08mm_Horizontal | J8 |
| 1 | STEPR | TerminalBlock_RND:TerminalBlock_RND_205-00232_1x02_P5.08mm_Horizontal | J9 |
Questions
How big is the Stepper sc PCB?
It measures 90 × 135.4 mm and has 2 copper layers, 1.6 mm thick.
What parts does the Stepper sc use?
24 parts, built around the BC547. 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 Stepper sc KiCad files?
From the smooker/cspcb repository on GitHub, at the commit this page was made from: the board is stepper_sc/stepper_sc.kicad_pcb and its schematic stepper_sc/stepper_sc.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the Stepper sc design in my own project?
Its repository states no licence, so its author keeps all rights: ask smooker before reusing the design.
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