Wiring Overview
Complete electrical system architecture and wiring guidelines
Close-up demonstration of all electrical connections, including power distribution, servo wiring, and UI components
⚠️ Safety First
- • Disconnect power before making any wiring changes
- • Double-check polarity on all power connections (red=+, black=−)
- • Never exceed 6V on servo power supply
- • Use proper wire gauges: 22-24 AWG for signals, 18-20 AWG for power
- • Insulate exposed connections with heat shrink tubing
System Architecture
The Fabrica electronics system consists of 4 main components:
1. Raspberry Pi Pico 2W
Brain of the system. Runs MicroPython code, processes button inputs, controls LED, and communicates with servo controller via I2C.
2. PCA9685 Servo Controller
16-channel PWM driver. Receives commands from Pico via I2C and generates PWM signals for up to 16 servos simultaneously.
3. Power Supply (5-6V)
Provides high-current power to servos (3-5A recommended). Pico is powered separately via USB or shared power rail.
4. User Interface
4 push buttons for manual control + 1 LED for status indication. Buttons use internal pull-up resistors (no external components needed).
System Block Diagram
Required Tools & Materials
Tools
- ✓ Soldering iron (temperature-controlled recommended)
- ✓ Solder (rosin-core, 60/40 or lead-free)
- ✓ Wire strippers (22-18 AWG)
- ✓ Flush cutters
- ✓ Small Phillips screwdriver
- ✓ Multimeter (for continuity and voltage checks)
- ✓ Heat shrink tubing + heat gun (optional but recommended)
Materials
- ✓ Jumper wires (male-to-male, male-to-female)
- ✓ Breadboard or terminal blocks
- ✓ 22 AWG solid core wire (red, black, other colors)
- ✓ JST connectors (for servo extension if needed)
- ✓ Electrical tape
- ✓ Cable ties / zip ties
- ✓ Dupont connectors (optional, for custom cables)
Wiring Color Standards
Follow these color conventions for consistency and easier troubleshooting:
Red Wire
Always positive (+) or VCC. Power supply positive terminal, servo positive pins.
Black/Brown Wire
Always ground (−) or GND. Common ground for all components.
Yellow/Orange Wire
Signal/PWM lines. Servo control signals from PCA9685.
Blue/Green Wire
I2C signals (SDA/SCL). Data communication between Pico and PCA9685.
Purple/White Wire
GPIO signals. Button inputs and LED output.
Green Wire
Alternative ground or secondary signals. Use when black wire is unavailable.
Quick Pin Reference
Raspberry Pi Pico 2W Pins
PCA9685 Connections
🔌 Wiring Best Practices
- 1. Common ground: Ensure Pico, PCA9685, and power supply share a common ground connection.
- 2. Strain relief: Secure wires near connectors to prevent stress on solder joints.
- 3. Wire management: Bundle wires with cable ties. Keep power and signal wires separated to reduce noise.
- 4. Test incrementally: Wire one component at a time and test before moving to the next.
- 5. Label everything: Use tape or labels to mark servo channels and button functions.
- 6. Use ferrules: Crimp ferrules on stranded wire ends for secure terminal block connections.
- 7. Check continuity: Use multimeter to verify connections before powering on.
- 8. Fuse protection: Consider adding a 3-5A fuse on the power supply line for safety.
Ready to Wire!
You now understand the overall electrical architecture. The next sections provide detailed step-by-step wiring instructions for each subsystem.
Next: Proceed to Power & Servos to wire the main power distribution and servo connections.