Electrical & Electronics Guide (2025 Updated)

Learn to wire and configure your FRC robot's electrical system safely and correctly with 2025 rule updates

🆕 2025 Battery Safety Rule Change

IMPORTANT: For safety reasons, teams may ONLY bring COTS (Commercial Off-The-Shelf) batteries to events. Custom batteries assembled from individual cells are now PROHIBITED. This rule applies to all FRC 2025 events.

🆕 2025 Electrical Updates

Rule R707: COTS RFID/NFC systems now allowed for internal robot communication
Rule R302: Pre-made electrical boards and custom PCBs can be reused from previous seasons
NEO Vortex motor compatibility with SPARK Flex controllers

Step 1

FRC Electrical Components

Understanding the main electrical components is crucial. These are the core parts of every FRC robot.

Essential Components:

🔋 12V Battery - CRITICAL ROOKIE INFO!

18Ah sealed lead-acid battery (SLA) - Powers entire robot
⚡ Can supply over 180A briefly, arc over 500A when fully charged - DANGEROUS if mishandled!
🚨 ROOKIE MISTAKE: If polarities short together, ALL stored energy releases in a dangerous arc!
Must be secured in robot with approved battery backer - loose batteries are EXTREMELY dangerous!
⚠️ DON'T DROP BATTERIES! Can bend internal plates, create bulges, or crack case open

🔴 BATTERY MANAGEMENT (They Don't Teach This!)

Most rookie teams learn this the hard way during competition:

🔋 You need MULTIPLE batteries (minimum 3-4, ideally 6-8 for competition)
⚡ Use a FRESH, fully charged battery for EVERY match - no exceptions!
🚫 NEVER run multiple matches on same battery - causes brownouts and robot failures
📊 BROWNOUTS = voltage drops below ~7V = robot randomly resets = MATCH LOSS!
⏱️ Battery charging takes 2-4 hours - plan ahead! Create battery rotation schedule
🏷️ LABEL each battery with number/color and track charge cycles (max ~200-300 cycles)
💰 Budget $150-200 PER battery - a critical cost rookie teams forget!
🔌 At competition: Always have 2 batteries charging, 1 in robot, 1-2 ready to swap

💡 PRO TIP: Create a "Battery Manager" role on your team to track battery status at competitions!

⚡ Power Distribution Hub (PDH)

REV Robotics PDH (current standard)
Distributes power from battery to all components
Multiple power channels with different current limits
Built-in current monitoring
CAN bus connectivity

🤖 roboRIO 2.0

Main robot controller (brain)
Runs your robot code
Connects to Driver Station via WiFi or Ethernet
Has PWM, DIO, Analog, I2C, SPI ports
Power: 12V, 2A max from PDH

📡 Radio (OpenMesh OM5P-AN or AC)

Wireless communication between robot and Driver Station
Must be programmed with your team number
Powered by Voltage Regulator Module (VRM) or POE injector

🔌 Voltage Regulator Module (VRM)

Converts 12V to 12V/2A and 5V/2A
Powers Radio, cameras, LEDs
Critical for stable radio connection

⚠️ Safety First!

ALWAYS disconnect battery before wiring
Check polarity - red (+) and black (-)
Use proper wire gauges for current loads
No exposed wire - use heat shrink or electrical tape

Step 2

Power Distribution Setup

The PDH is the heart of your electrical system. All power flows through it.

PDH Channel Types:

High Current Channels (40A) - Channels 0-9, 12-21 - Use for motors
Low Current Channels (15A) - Channels 10-11, 22-23 - Use for PCM, VRM, etc.

Wiring Steps:

Mount PDH Securely
Use 4 screws to mount PDH to robot frame. Keep it accessible but protected!
Connect Battery
Use 6 AWG red (+) and black (-) wire. Connect to main power terminals on PDH.
- Strip 20mm of wire insulation
- Insert into Wago connector and close lever
- Tug test - wire should not pull out!
Install 120A Circuit Breaker
REQUIRED for safety! Goes between battery and PDH. Protects against short circuits.
Connect roboRIO Power
Use a dedicated channel (typically channel 22 or 23). Use 18 AWG wire, strip 12mm.
Label Everything!
Use label maker or tape. Note which channel powers which device. This saves hours of troubleshooting!

🔌 Wire Gauge Guide

6 AWG - Battery to PDH (main power)
10 AWG - High current motors (30-40A)
12 AWG - Medium motors (20-30A)
18 AWG - Light loads, roboRIO, VRM
22 AWG - Signal wires, sensors

⚡ WIRING SECRETS (Rookies Learn These the Hard Way!)

🏷️ LABEL EVERY WIRE AT BOTH ENDS! Write what it connects (e.g., "Intake Motor - PDH Ch 5")
🎨 Use color coding: Red=power(+), Black=ground(-), Yellow=PWM signal, Green=CAN, etc.
📏 LEAVE SLACK! Wires break when robot moves. Add 6-12 inches extra length for movement
🔒 Zip-tie EVERYTHING - but not too tight! Wires vibrate loose, secure them every 6-8 inches
⚠️ NEVER run power wires next to signal wires - causes electrical noise/interference!
🔧 Strip wire EXACTLY as specified - too much exposed wire = SHORT CIRCUIT risk!
🔥 Heat shrink > electrical tape for permanent connections. Tape comes loose!
🧪 TUG TEST after every connection - if wire pulls out, redo it! Will fail at competition!
📸 TAKE PHOTOS of your wiring before/after changes - you'll forget how it worked!
🛠️ Build a "Practice Bot" electrical board - use it for driver practice without risking competition bot

💡 PRO TIP: Organized pit = organized robot. Show up to competition with tools sorted and wiring labeled!

📊 Official Wiring Diagrams & Resources

For complete wiring diagrams showing roboRIO 2.0, PDH, SPARK MAX, and other components:

💡 These diagrams include detailed color-coded connections, wire gauges, and safety requirements.

Step 3

RoboRIO & Control System

The roboRIO is your robot's brain. It runs your code and coordinates all systems.

roboRIO Connections:

Power Connection
Connect 12V from PDH to roboRIO power input. Use proper polarity!
- Red wire to V+ terminal
- Black wire to ground (GND) terminal
Radio Connection (Ethernet)
Connect roboRIO to radio using CAT5e/CAT6 Ethernet cable. This enables wireless programming and control.
CAN Bus Connection
Yellow and Green twisted pair connects roboRIO to PDH and motor controllers.
Image the roboRIO
Before first use, image roboRIO with latest firmware using roboRIO Imaging Tool (Windows only).
roboRIO Imaging Guide

🔍 roboRIO Ports Overview

PWM (0-9) - Motor controllers (non-CAN), servos
DIO (0-25) - Digital sensors (limit switches, encoders)
Analog In (0-3) - Analog sensors (potentiometers, ultrasonic)
CAN - SPARK MAX, Talon FX, PDH, PCM
I2C, SPI - Advanced sensors (gyros, cameras)

Step 4

CAN Bus Wiring

CAN (Controller Area Network) allows devices to communicate digitally. It's how motor controllers send data back to roboRIO!

CAN Bus Basics:

What is CAN Bus?

Two-wire communication (Yellow + Green twisted pair)
Bi-directional - devices can send AND receive data
Daisy-chain topology (one device to next)
Requires 120Ω termination resistors at BOTH ends

Wiring CAN Bus:

Start at roboRIO
roboRIO has built-in 120Ω termination. This is one end of your CAN bus.
Daisy-Chain to PDH
Connect roboRIO CAN to PDH CAN port. Use yellow to yellow, green to green.
Connect Motor Controllers
From PDH, daisy-chain to each SPARK MAX or other CAN motor controller.
- Order doesn't matter on CAN bus
- Keep wires short and organized
Terminate at Last Device
PDH has built-in termination if it's the last device. Otherwise, add 120Ω termination resistor!

⚠️ Common CAN Bus Mistakes

No termination resistors - causes communication errors
Swapped yellow/green wires - won't work!
Star topology instead of daisy-chain - unreliable
Loose connections - causes intermittent failures

💡 CAN Device IDs

Remember: Each CAN device needs a unique ID (1-62). You set these in REV Hardware Client or Phoenix Tuner!

Step 5

Motor Controllers & PWM

Motor controllers regulate power to motors. Modern controllers use CAN, but PWM is still used for some devices.

Common Motor Controllers:

⚡ SPARK MAX (REV Robotics)

CAN or PWM control
Controls NEO brushless or brushed motors
Built-in encoder support
Data port for USB configuration

🦅 Talon FX (CTRE)

CAN bus only
Integrated with Falcon 500 motor
High-performance for drivetrains

Connection Methods:

CAN Connection (Recommended)
Connect motor controller to CAN bus as described in Step 4. This allows:
- Reading encoder values
- Current monitoring
- Temperature sensing
- Advanced control modes (PID, Motion Profiling)
PWM Connection (Legacy)
Connect 3-pin PWM cable from motor controller to roboRIO PWM port (0-9).
- Simpler but limited - no feedback!
- Good for servos, simple motors
Power Connection
ALL motor controllers get power from PDH channels. Match wire gauge to motor current draw!

🎨 Color Coding

Standard wire colors for motor controllers:

Red - Positive (+) power
Black - Ground (-)
Yellow - CAN High
Green - CAN Low

Step 6

Pneumatics System

Pneumatics use compressed air for fast, powerful linear motion. Great for grippers, shifters, and extending mechanisms!

Pneumatic Components:

💨 Compressor

Fills air tanks to 120 PSI max
Powered by Spike relay or motor controller
Controlled by Pneumatic Control Module (PCM)

🗜️ Air Tanks

Store compressed air
Typically 2 tanks (0.5L each)
Must be securely mounted

🎛️ Pneumatic Control Module (PCM)

Controls solenoid valves
Connects via CAN bus
8 solenoid channels
Automatically manages compressor

🔧 Solenoid Valves

Single solenoid - one direction control
Double solenoid - both directions controlled
Electronically switches air flow to cylinders

Pneumatics Setup:

Install Pressure Relief Valve
REQUIRED for safety! Set to 125 PSI. Prevents over-pressurization.
Connect Air Tanks
Use approved pneumatic tubing. Connect tanks in parallel for more capacity.
Mount PCM and Connect to CAN
PCM gets power from PDH and data via CAN bus. Set unique CAN ID!
Wire Compressor
Compressor connects to PCM compressor output. PCM automatically turns on/off to maintain pressure.
Connect Solenoids and Cylinders
Solenoids plug into PCM (0-7). Pneumatic tubing connects solenoids to cylinders.

⚠️ Pneumatics Safety

NEVER exceed 120 PSI
Always install pressure relief valve
Check for air leaks regularly
Secure all tubing with zip ties
Wear safety glasses when working with pressurized air

Step 7

Testing & Troubleshooting

Before driving your robot, systematically test all electrical systems. Methodical testing prevents damage and competition failures!

Pre-Power Checklist:

Visual Inspection
- All wires secured (no loose connections)
- No exposed wire or damaged insulation
- Correct polarity on all connections
- Battery securely mounted
Continuity Testing
Use multimeter to check for short circuits BEFORE connecting battery!

Power-On Testing:

Connect Battery (Circuit Breaker OFF)
Connect battery with circuit breaker in OFF position. Nothing should power on yet!
Flip Circuit Breaker ON
Watch for:
- PDH LED - should be solid green
- roboRIO - 3 LEDs (power, status, radio)
- Radio - should boot and show lights
- NO smoke, sparks, or burning smells!
Check Driver Station Connection
Open FRC Driver Station. Connect laptop to robot WiFi network. Should see green communications indicator!
Test Motors (Wheels OFF Ground!)
CRITICAL: Put robot on blocks or have team members hold it up. Enable robot and test each motor at LOW speed first!

Common Problems & Solutions:

🔴 roboRIO Won't Boot

Check 12V power to roboRIO
Verify correct polarity (red to +, black to -)
Try re-imaging roboRIO

📡 No Robot Communication

Check radio power and Ethernet connections
Verify robot is on correct WiFi network
Re-program radio with team number
Check firewall settings on laptop

⚙️ Motor Not Working

Check motor controller power (LEDs on controller)
Verify CAN or PWM connection to roboRIO
Check CAN ID is unique and matches code
Test motor controller with REV Hardware Client

🎉 Electrical System Complete!

Congratulations! You've learned the fundamentals of FRC electrical systems. Remember: good electrical practices prevent 90% of robot failures. Keep wires organized, label everything, and test thoroughly!