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Overview

Proper electrical design is crucial for robot safety and functionality. Even if you don’t fabricate a custom PCB, a clear wiring diagram ensures correct connections and helps troubleshoot issues.
Deliverable: Wiring diagram showing all electrical connections Optional: Custom PCB design for cleaner, more reliable connections

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Wiring vs PCB

Wiring Diagram (Minimum Required)

  • Shows all connections between components
  • Can use breadboard, terminal blocks, or hand-soldered wires
  • Faster to prototype
  • Easier to modify during development
  • Recommended for first iteration

Custom PCB (Advanced, Optional)

  • Professional, compact solution
  • Reduces wiring errors
  • More reliable connections
  • Takes time to design and fabricate
  • Consider for final version

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Electrical System Architecture

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Power Distribution

Battery (12V, 5000mAh LiPo)
  ├─→ Main Switch / Fuse (10A)
  ├─→ 12V Bus
  │    ├─→ Motor Driver 1 (IBT-2)
  │    ├─→ Motor Driver 2 (IBT-2)
  │    ├─→ Motor Driver 3 (IBT-2)
  │    ├─→ Motor Driver 4 (IBT-2)
  │    └─→ Buck Converter (12V → 5V, 5A)
  └─→ 5V Bus
       ├─→ ESP32
       ├─→ Raspberry Pi
       ├─→ IMU (ICM-20948)
       └─→ LiDAR (USB powered via RPi)

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Signal Connections

ESP32 Microcontroller
  ├─→ Motor Drivers (PWM + Enable signals)
  │    ├─→ Driver 1: GPIO 4 (RPWM), GPIO 16 (LPWM)
  │    ├─→ Driver 2: GPIO 17, GPIO 18
  │    ├─→ Driver 3: GPIO 19, GPIO 21
  │    └─→ Driver 4: GPIO 22, GPIO 23
  ├─→ Encoders (Quadrature signals)
  │    ├─→ Encoder 1: GPIO 32 (A), GPIO 33 (B)
  │    ├─→ Encoder 2: GPIO 25, GPIO 26
  │    ├─→ Encoder 3: GPIO 27, GPIO 14
  │    └─→ Encoder 4: GPIO 12, GPIO 13
  ├─→ IMU: I2C (SDA: GPIO 21, SCL: GPIO 22)
  └─→ Raspberry Pi: USB Serial (optional)

Raspberry Pi
  ├─→ LiDAR: USB
  ├─→ Camera: CSI ribbon cable
  └─→ ESP32: USB or UART (GPIO 14/15)

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Component Specifications

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Power Requirements

ComponentVoltageCurrent (Typ)Current (Peak)Notes
DC Motor (each)12V0.5A3APeak at stall/startup
ESP325V0.5A0.8AVia USB or VIN
Raspberry Pi 4/55V1.5A3AHigher if using USB devices
IBT-2 Driver (each)12V logic50mA-Logic only, motor power separate
IMU ICM-209483.3V15mA-ESP32 provides 3.3V
LiDAR A1M85V400mA500mAVia USB from RPi
Total Power Budget:
  • Motors: 4 × 0.5A = 2A typical, 12A peak (brief)
  • ESP32: 0.5A
  • Raspberry Pi: 2A
  • LiDAR: 0.5A
  • Total @ 5V: ~3A typical
  • Total @ 12V: ~2A typical, ~12A peak
Safety: Use appropriate fuses! 10A fuse on main 12V line, 5A fuse on 5V buck converter output.

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Wiring Diagram Design

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Tool Options

Pros:
  • Free, powerful
  • Professional-grade
  • Active community
  • Cross-platform
Cons:
  • Steeper learning curve
Download: https://kicad.org/
Pros:
  • Visual breadboard view
  • Easy for documentation
  • Good for prototyping diagrams
Cons:
  • Less professional
  • Limited for complex designs
Download: https://fritzing.org/
Pros:
  • Industry standard
  • Powerful simulation
  • University license available
Cons:
  • Complex for beginners
  • Windows only
Access: Check university software portal

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Creating the Wiring Diagram

Step-by-step in EasyEDA:
  1. Create New Project
    • Sign in to EasyEDA
    • New Project → “Mecanum Robot”
    • New Schematic
  2. Add Components
    • Search library for: ESP32, IBT-2, etc.
    • If not found, create custom symbol or use generic blocks
    • Place all components on canvas
  3. Draw Connections
    • Power connections (red for +, black for GND)
    • Signal wires (different colors for clarity)
    • Label all nets (e.g., “MOTOR1_PWM”, “ENC1_A”)
  4. Add Annotations
    • Component values (resistor values, capacitor values)
    • Voltage levels
    • Pin numbers
    • Wire gauge recommendations
  5. Design Rules Check
    • Verify no floating pins
    • Check all grounds connected
    • Confirm polarities (power supplies)

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Wire Gauge Selection

Choose appropriate wire gauge (AWG) for current:
CurrentMinimum AWGRecommended AWGNotes
< 0.5A24 AWG22 AWGSignal wires, logic
0.5-2A22 AWG20 AWG5V power distribution
2-5A20 AWG18 AWGMotor power, 12V bus
5-10A18 AWG16 AWGMain battery leads
Color Coding: Use consistent colors:
  • Red: Positive power
  • Black: Ground
  • Yellow: PWM signals
  • Green/Blue: Encoder signals
  • White: Serial communication

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Connectors and Terminals

Power:
  • XT60 or XT30 for battery (anti-spark, high current)
  • Screw terminals for power distribution
  • Fuse holders inline
Signal:
  • Dupont connectors (2.54mm pitch) for breadboard-style
  • JST connectors for permanent connections
  • Pin headers for modular connections
Motors:
  • Bullet connectors or solder direct
  • Consider quick-disconnect for easy removal

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Terminal Block Layout

For wire management without PCB: 
12V Distribution Block:
  [12V IN] [Motor1+] [Motor2+] [Motor3+] [Motor4+] [Buck+]

GND Distribution Block:
  [GND IN] [Motor1-] [Motor2-] [Motor3-] [Motor4-] [Buck-] [Logic GND]

5V Distribution Block:
  [5V Buck] [ESP32] [RPi] [Sensors]

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PCB Design (Advanced)

If you choose to design a custom PCB:

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PCB Design Steps

1

Schematic Capture

Create complete schematic with all components and connections in EasyEDA or KiCad
2

Footprint Assignment

Assign physical footprints to each component (THT vs SMD, package size)
3

PCB Layout

Arrange components on board, considering:
  • Power distribution first
  • Signal routing
  • Thermal management (motor drivers)
  • Mechanical constraints (mounting holes, size)
4

Routing

Connect all traces:
  • Power traces wide (2-3mm for high current)
  • Signal traces thin (0.3-0.5mm)
  • Ground plane (pour copper on bottom layer)
5

Design Rule Check (DRC)

Verify no errors, proper clearances, manufacturability
6

Generate Gerber Files

Export manufacturing files for PCB fabrication house
7

Order PCBs

Upload to JLCPCB, PCBWay, or other service (~$5 for 5 boards, 1-2 week delivery)

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PCB Design Guidelines

Trace Width: 
Signal traces: 0.3mm minimum
5V power: 1mm (up to 2A)
12V motor power: 2-3mm (up to 5A)
Ground plane: Fill remaining area
Layer Stack: 
2-layer PCB (sufficient):
  Top: Components + signal routing
  Bottom: Ground plane + power routing

4-layer PCB (professional, expensive):
  Layer 1: Signal
  Layer 2: Ground plane
  Layer 3: Power plane
  Layer 4: Signal
Mounting:
  • Add 3-4mm mounting holes at corners
  • M3 size (3.2mm holes)
  • Keep components >5mm from board edge

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Safety Considerations

Critical Safety Items:
  • Main battery fuse: 10A
  • 5V regulator fuse: 5A
  • Fuse should blow before wires melt
  • Use automotive blade fuses (easy to replace)
  • LiPo batteries can catch fire if damaged
  • Use LiPo safety bag for storage
  • Don’t over-discharge (<3.0V per cell)
  • Balance charging required
  • Emergency disconnect switch mandatory
  • Double-check polarity before powering on
  • Insulate all exposed connections (heat shrink, electrical tape)
  • Secure wires with zip ties (prevent movement into fan blades)
  • Test with multimeter before connecting battery
  • Motor drivers can get HOT (60-80°C)
  • Ensure airflow or add heatsinks
  • Don’t enclose drivers in sealed box
  • Monitor temperature during initial testing

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Testing Procedure

Before full power-on:
1

Visual Inspection

  • Check all connections match diagram
  • Verify no loose wires
  • Confirm polarity of all power connections
2

Continuity Testing

  • Use multimeter in continuity mode
  • Verify GND connections (should beep)
  • Check NO shorts between power rails
3

Power Supply Test

  • Connect power supply (not battery yet)
  • Measure voltages at each component
  • Verify 12V and 5V rails correct
4

Low-Power Test

  • Power ESP32 only via USB
  • Test all GPIO outputs with LED
  • Verify signal levels
5

Motor Test (One at a Time)

  • Connect ONE motor driver + motor
  • Test with limited PWM duty cycle (20%)
  • Verify rotation and encoder signals
  • Repeat for all motors
6

Full System Test

  • Connect all components
  • Power from battery
  • Monitor current draw
  • Test all functions

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Documentation Requirements

Your wiring diagram should include:
  • All components labeled with designators (U1, M1, etc.)
  • All connections shown clearly
  • Wire colors indicated
  • Pin numbers labeled
  • Voltage levels marked
  • Current ratings noted
  • Component values (resistors, capacitors)
  • Connector types specified
  • Legend/notes explaining symbols
  • Revisions/version number

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Example Projects

Study these open-source robot electrical designs:
  • ROS2 Turtlebot: Simple diff-drive wiring
  • Arduino Robot Car: Similar motor driver setup
  • DIY Roomba: Power distribution examples

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Next Steps

Mechanical Assembly

Integrate electrical and mechanical systems

ESP32 Basics

Learn ESP32 GPIO and programming

Motor Driver Guide

Understand IBT-2 motor driver

Hardware Reference

Complete component specifications

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References

[1] EasyEDA Tutorial: https://easyeda.com/page/tutorial [2] Wire Gauge Chart: https://www.powerstream.com/Wire_Size.htm [3] LiPo Battery Safety: https://www.robotshop.com/community/tutorials/show/lipo-battery-guide