Anatomy of an FTC robot's electronics

An FTC robot's electronics are simpler than they look. There are about seven things, and once you can name all of them, wiring becomes a checklist rather than a mystery.

The required parts

12V battery

The only power source on the robot. A rechargeable pack that plugs into the main power switch.

Main power switch

A physical switch with a built-in breaker, wired directly between the battery and everything else. Required, and inspectors check it.

Control Hub

The brain. It is an Android computer with motor ports, servo ports, sensor ports, and power outputs built in. It runs your Java.

Motors

DC motors with encoder cables, plugged into the Hub's motor ports. Most robots use four for the drivetrain plus one or two for mechanisms.

Servos

Small positional actuators for claws, wrists, and flippers. They plug into servo ports and draw power from the Hub.

Driver Station

A phone or approved device the drivers hold, with gamepads attached. It talks to the Control Hub over a wireless link.

Expansion Hub

Optional. A second hub that adds more motor and servo ports, connected to the Control Hub. You need one only when you run out of ports.

How power flows

Power takes exactly one path, and understanding it explains most electrical failures:

1. Battery — stores roughly 12V.
2. Main switch and breaker — everything on the robot passes through here. Flipping it kills the robot completely.
3. Control Hub — takes battery power in through an XT30 connector, then distributes it.
4. Motor ports — the Hub sends variable power to each motor based on your setPower() calls.
5. Servo ports — the Hub supplies a regulated voltage to servos.
6. Sensor ports — low-power connections for I2C, digital, and analog sensors.

What the Control Hub gives you

A single Control Hub typically provides:

• 4 motor ports — each with a matching encoder input
• 6 servo ports
• 4 I2C buses — for sensors like an IMU, colour sensor, or distance sensor
• 8 digital ports — for touch sensors and limit switches
• 4 analog ports — for potentiometers and some distance sensors
• A built-in IMU — gives you robot heading without buying anything

That last one matters more than rookies realise: the built-in IMU means field-relative driving and heading-correcting autonomous are available on day one with no extra hardware.

When you need an Expansion Hub

Four motor ports go quickly: a four-wheel drivetrain uses all of them. The moment you add a motorised mechanism you need more.

An Expansion Hub connects to the Control Hub and doubles your ports. It also has its own power connection to the main switch — it does not draw power through the Control Hub.

Why more matches are lost here than in code

The failure modes are mundane and all preventable:

• A motor cable works loose from vibration mid-match.
• The XT30 power connector to a hub is not fully seated.
• The battery was not charged, and the robot browns out under load.
• A cable runs through a moving mechanism and gets cut.
• The main switch is mounted where a defensive robot can hit it.

None of these are clever problems. They are all fixed by careful routing, strain relief, and a pre-match checklist — which the rest of this unit covers.

Check yourself

Your robot suddenly goes completely dead mid-match — no motors, no telemetry, driver station shows a disconnect. What should you check first?

• AYour TeleOp code for an infinite loop
• BThe battery connection and the main power switch
• CThe servo port assignments
• DThe I2C sensor addresses

Next

Now that you can name the parts, the next lesson wires them — in the correct order, with the mistakes called out as you go.