Power & Servos Wiring
Power distribution and servo motor connections
10 min read
30-45 min work
⚠️ Power Safety
- • Always disconnect power before making wiring changes
- • Verify voltage: Must be 5-6V DC (NOT 12V)
- • Check polarity: Red=positive, Black=ground
- • Current capacity: Minimum 3A, recommended 5A
Power Supply Requirements
Specifications
- Voltage: 5V DC or 6V DC
- Current: 3-5A minimum (5A recommended)
- Type: Switching power supply or USB PD
- Connector: Barrel jack (5.5mm×2.1mm) or screw terminals
Current Needs
- Per servo: ~500mA peak (200mA idle)
- 4 servos: 2A peak
- 8 servos: 4A peak
- 16 servos: 8A peak
PCA9685 Power Connections
Logic Power (3.3V)
- • VCC → 3.3V from Raspberry Pi Pico (Pin 36)
- • GND → GND from Pico
Powers the PCA9685 chip for I2C communication only.
Servo Power (5-6V)
- • V+ → Power supply positive
- • GND → Power supply ground
High-current power goes directly to servos.
Servo Channel Wiring
Standard Servo Wire Colors
Orange/Yellow
Signal (PWM)
Red
Power (+5V/+6V)
Brown/Black
Ground (−)
Connect each servo to a PCA9685 channel (0-15) based on your panel layout.
Best Practices
✅ Do
- • Use thick wires (18-20 AWG) for power lines
- • Add a 100µF capacitor near PCA9685 V+ and GND
- • Connect all grounds together (common ground)
- • Use terminal blocks for easy disconnection
- • Add a fuse (3-5A) for protection
❌ Don't
- • Power servos from Pico's 3.3V pin
- • Use USB power alone (insufficient current)
- • Exceed 6V on servo power
- • Mix different voltage supplies
- • Skip the capacitor (causes voltage spikes)
Testing Power Connections
- 1. Power Off Test: Check all connections with multimeter (continuity mode)
- 2. Voltage Test: Power on WITHOUT servos connected. Verify 5-6V at V+ terminal
- 3. Single Servo Test: Connect one servo to Channel 0. Run calibration code
- 4. Full System Test: Connect all servos. Verify no voltage drop under load