Hardware Setup Guide

Component Overview

Raspberry Pi Pico

• Model: Raspberry Pi Pico (RP2040)
• Purpose: Sensor data collection and processing
• Connections: USB serial to RPI, GPIO pins to sensors

HC-SR04 Ultrasonic Sensors

• Quantity: 8 sensors
• Range: 2cm - 400cm
• Accuracy: ±3mm
• Operating Voltage: 5V DC

LEGO Spike Prime Hub

• Purpose: Robot movement and motor control
• Communication: Bluetooth LE to computer
• Firmware: PyBricks (replaces LEGO firmware)

Raspberry Pi (Interface)

• Model: Any Pi with USB ports
• Purpose: Serial communication bridge
• OS: Raspberry Pi OS or compatible Linux

Wiring Diagrams

Pico to HC-SR04 Sensor Connections

Pico GPIO Layout:
┌─────────────────────────────────────┐
│  GP0  GP1  GND  GP2  GP3  GP4  GP5 │
│  GP6  GP7  GND  GP8  GP9  GP10 GP11│
│  GP12 GP13 GND GP14 GP15 3V3  GP16 │
│  GP17 GND GP18 GP19 GP20 GP21 GP22 │
│  RUN  GP26 GP27 GND  GP28 ADC  3V3 │
│  3V3  VSYS GND  EN   GND  VBUS    │
└─────────────────────────────────────┘

Sensor Pin Assignments

Sensor Position	Trigger Pin	Echo Pin
Front Left	GP2	GP3
Front Right	GP4	GP5
Left Front	GP6	GP7
Left Back	GP8	GP9
Right Front	GP10	GP11
Right Back	GP12	GP13
Back Left	GP14	GP15
Back Right	GP16	GP17

Power Distribution

• 5V Supply: External power supply for HC-SR04 sensors
• 3.3V: Pico internal supply for logic levels
• Ground: Common ground for all components

Power Supply Schematic:
5V Supply ──┬── HC-SR04 VCC (×8)
            │
            └── Level Shifter (5V side)
            
Pico 3.3V ──┬── Level Shifter (3.3V side)
            │
            └── Pico GPIO pins
            
Common GND ──┴── All component grounds

Physical Mounting

Robot Chassis Layout

    Front
     ↑
[FL] [FR]  ← Front sensors
[LF]   [RF] ← Side sensors  
[LB]   [RB] ← Side sensors
[BL] [BR]  ← Back sensors
     ↓
    Back

Sensor Positioning

• Height: 10-15cm above ground
• Angle: Perpendicular to robot surface
• Clearance: 5cm minimum from obstacles
• Protection: Sensor housings recommended

Cable Management

• Use ribbon cables for organized wiring
• Secure cables to prevent interference with movement
• Label all connections for maintenance
• Provide strain relief at connection points

Spike Prime Configuration

Motor Connections

• Port A: Left drive motor
• Port B: Right drive motor
• Port C: Optional auxiliary motor
• Port D: Optional auxiliary motor

Sensor Connections (Optional)

• Port 1: Color sensor (if used)
• Port 2: Distance sensor (if used)
• Port 3: Force sensor (if used)
• Port 4: Gyro sensor (built-in)

PyBricks Firmware Installation

1. Connect hub via USB
2. Visit code.pybricks.com
3. Follow firmware installation wizard
4. Verify installation with test program

Testing and Calibration

Sensor Testing

# Test individual sensor
def test_sensor(trigger_pin, echo_pin):
    # Send trigger pulse
    # Measure echo response
    # Calculate distance
    # Verify range and accuracy

Calibration Procedure

1. Distance Calibration

   • Place known objects at measured distances
   • Record sensor readings
   • Calculate correction factors
   • Update firmware constants

2. Angular Calibration

   • Verify sensor mounting angles
   • Test detection patterns
   • Adjust physical positioning if needed

System Integration Test

1. Power on all components
2. Verify serial communication
3. Test sensor data flow
4. Validate movement commands
5. Check emergency stop functionality

Troubleshooting

Common Hardware Issues

Sensor Problems

• No readings: Check power and wiring
• Erratic readings: Verify ground connections
• Short range: Clean sensor surfaces
• Interference: Separate sensors physically

Communication Issues

• No serial data: Check USB connections
• Garbled data: Verify baudrate settings
• Intermittent connection: Check cable integrity

Power Issues

• System resets: Check power supply capacity
• Voltage drops: Verify wire gauge and connections
• Noise: Add decoupling capacitors

Diagnostic Tools

• Multimeter for voltage/continuity testing
• Oscilloscope for signal analysis
• Logic analyzer for digital communication
• Serial terminal for message monitoring

Safety Considerations

Electrical Safety

• Use appropriate fuses/circuit breakers
• Verify polarity before connecting power
• Isolate high and low voltage sections
• Provide emergency stop capability

Mechanical Safety

• Secure all mounting hardware
• Protect exposed wiring
• Ensure stable robot base
• Test emergency stop procedures

Software Safety

• Implement watchdog timers
• Add bounds checking for all inputs
• Provide graceful failure modes
• Log all system events for debugging