how do I wire a servo

To wire a servo, plug its standard three-wire connector into one of the six built-in servo ports on your Control Hub or Expansion Hub, ensuring the black ground wire aligns with the ground pin on the left side of the port. The official FTC Docs emphasize matching the black, red, and white wires with the color-coded symbols on the hub. Because standard servo connectors can easily be plugged in backward without physical resistance, Game Manual 0 advises double-checking this alignment if the servo does not function .

When using servo wire extensions, Game Manual 0 recommends choosing heavy-duty wires and securing the connections with retaining clips or electrical tape to prevent them from pulling apart. If you are using a VEX Motor Controller 29, you must use an adapter cable or install the correct connector on the wires, and you should physically protect the controller from impacts .

For clean and reliable routing, the FTC Docs recommend bundling wires along a defined path using wire management hardware like cable ties, sheaths, or grommets to keep them stationary and protected. If the servo is mounted on a moving part, you should form the bundled wires into a flexible service loop to accommodate movement without pinching or twisting. Additionally, avoid routing servo wires directly next to USB cables to prevent signal interference .

If you are using a REV Servo Hub, wiring instructions are covered in the REV Robotics Docs on Servo Hub Wiring (https://docs.revrobotics.com/rev-crossover-products/servo/servo-hub/servo-hub-wiring) .

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Wiring Guide > Specific Recommendations > Servo Wires

Game Manual 0·CC BY-NC 4.0

Using heavy-duty extension wires are recommended.

Tape the connections between extension wires and servo wires with electrical tape. This is as the connections can become loose over time and are easy to pull out.

The VEX Motor Controller 29 has the wrong gender connector on the 3-pin end. You are required to either use an adapter cable, or add the right connector to the wires (recommended). Be sure to protect the MC29, as it is fragile and prone to failure if it takes impact from another object.

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Connecting a Servo to the Hub > Connecting a Servo to the Hub Instructions

FTC Docs·BSD 3-Clause

Connect the servo cable to the servo port labeled "0" on the Hub.

Note that the ground pin is on the left side of the servo port.

Verify that the black ground wire of the servo cable matches the

ground pin of the servo port (which is aligned on the left side of the port).

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Connecting a Servo to the Hub

FTC Docs·BSD 3-Clause

The Hub has 6 built-in servo ports. The servo ports accept the standard 3-wire header style connectors commonly found on servos. Note that ground pin is on the left side of the servo port.

Note that it will take an estimated 2.5 minutes to complete this task.

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Robot Wiring Guide > Common Problems and Troubleshooting

FTC Docs·BSD 3-Clause

Hardware Issues

Before wiring a robot, make sure to inspect the ports on all the modules. It is possible to damage the pins in the module ports. If this is the case, do not use the module; it should be sent back to the manufacturer for repairs.

Reversed Wires

The Expansion Hub and the Control Hub have three color-coded symbols that align the servo wire colors.
Be sure to match the black, red, and white wires with the color-coded symbols on the Hub.
Check the connection on servo extensions and splitters too.
Check tightness of XT30 connections. Over time the male "pins" compress, and the connector becomes loose. Follow the

REV Robotics XT30 pin troubleshooting guide (https://docs.revrobotics.com/duo-control/troubleshooting-the-control-system/control-hub-troubleshooting).

(Figure: Color-coded symbols)

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Servo Hub Wiring | REV Crossover

This source does not publish a licence, so its text is not reproduced here. Open the source to read it.

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Robot Wiring Guide > Best Practices > Wire Management

FTC Docs·BSD 3-Clause

The most important step towards neat wiring is the implementation of proper wire management. Wire management involves bundling and routing wires along a defined path to the various electrical parts.

(Figure: Multiple wire management types

This robot utilizes multiple actuators, requiring level converters, boosters, and wire extensions. Clutter is eliminated by organizing a logical flow through the robot, then bundling and constraining wire clusters wherever possible.
Four encoder level converters are mounted to a plastic plate which is bolted to the main chassis. Wires to and from these converters are strain relieved on either side.
Motor wires pass through Anderson Powerpole connectors and are bundled and restrained.
Servo PWM cables (and their extensions) are grouped in a flat bundle and routed to a servo booster module. Wires from the booster module are bundled and wrapped with a spiral sheath which runs all the way up the arm support to the rotating grabber. A service loop is created and attached to the arm on one side, and the grabber on the other side.)

Tips to keep in mind to ensure neat, robust wiring:

Keep the wiring stationary.
Protect the wiring.
Where possible, make sure all cables are the correct length.
Bundle cables together if they are running to a common destination.
Use right-angle USB connectors if they keep wiring more compact.
Use wire management hardware.
Self-adhesive cable tie mounts help attach wires to surfaces without holes.
Grommets protect wires from damage from sharp edges.
Wire sheaths allow teams to quickly protect at-risk wiring.

(Figure: Wire management hardware)

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Choosing a Servo > Recommended Servos

Game Manual 0·CC BY-NC 4.0

Tip: Being able to read the absolute position of the servo can have significant benefits when programming your robot. For example, you can tell the servo to go to a position, wait for it to reach that position, then do the next action; as opposed to telling the servo to go to a position, waiting a set amount of time (which may be longer or shorter than the time actually needed), then doing the next action.

Important: The Axon MINI MK2 (https://axon-robotics.com/products/mini) is very similar to the MAX in terms of total output power (though geared at a slightly faster speed/lower torque), and has the same features (including the heat treated stainless steel gears, programmability, and analog output wire). However, this servo is a slightly different form factor to the standard form factor used by the other servos on this list. While the height is shorter than the MAX, it is slightly wider, and the servo horn is in a different position compared to the standard servo size. Due to this, we don't recommend the MINI for anything other than fully custom-designed mechanisms not relying on standard mounts and horn position.

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Robot Wiring Guide > Best Practices > Wires on Moving Parts

FTC Docs·BSD 3-Clause

Most robots have one or more components that move relative to the main drive chassis. This could be things like a pivoting arm, an extending collector, or a shooter turntable. When these components have motors and sensors attached, it is important to ensure that the connecting wires can accommodate the movement. There are several precautions that can be taken to ensure that wires do not get pinched, twisted, or entangled.

Constraining wires is the first line of defense. An unconstrained wire is likely to get caught and pulled as one component moves past another. However, moving parts often need "extra" wire when they are fully extended or rotated, so it is important to plan this extra wire when the part is retracted. The extra wire should be formed into a "service loop," which keeps wires bundled together and provides predictable movement. These bundled wires can be further protected by an expandable, spiral, or split sheathing. This sheathing serves as a flexible outer protector for the wire bundle as it moves near potential pinch/entanglement points.

(Figure: Wires near moving parts

The upper motor is mounted to a movable arm, which rotates relative to the robot chassis.
The motor's power and encoder wires have been bundled (yellow and green zip ties) into a service loop.
Wires are anchored to the motors (white zip ties). This maintains control over the wires when the arm rotates and ensures that none are pinched.)

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Servo Usage Tips

Game Manual 0·CC BY-NC 4.0

Below are some tips on using servos in FTC®.

Do not backdrive servos. Forcibly rotating a powered servo away from its position risks damaging the internal gears.
Pay attention to a servo's travel range! The default 600-2400 range of the FTC control system when selecting the "Servo" configuration can make it appear that popular servos like the goBILDA Dual Mode Servos and REV Smart Robot Servos have less range than advertised. Make sure you select the "Full Range Servo" configuration instead to get the full 500-2500 range.
Servo wires usually are black-red-white or black-red-yellow. Matching the colors is an easy way to check if the servo is plugged in correctly. Most servo connectors provide no protection from plugging them the wrong way: if you rotate it 180 degrees, it will still fit - but the servo would not work. (It shouldn't be damaged, though.) Thus, if your servo is not working, first check if they are plugged in correctly. Then check it again.
When using servo wire extensions, use retaining clips (https://www.gobilda.com/servo-connector-clip-yellow-6-pack/) to prevent the connection from coming apart when someone pulls on the wire. Alternatively, electrical tape will work in a pinch.

Tip: Some vendors sell versions of the 3-pin female connector with retaining clips built-in. BackBayRC on Amazon sells pre-made servo extension wires with locking connectors (https://www.amazon.com/BackBayRC-Extension-Strands-Vehicles-bikes/dp/B0CXR2YBS4/); and Ferra Components sells both pre-made servo extension wires with locking connectors (https://ferracomponents.com/products/20awg-locking-servo-wire), and packs of locking connectors you can crimp yourself (https://ferracomponents.com/products/servo-locking-connector).

Do not use bare socket head screws to attach servos - when tightened, they will damage the plastic. Use button head screws or socket heads with a washer.
Servos break very easily when subjected to lateral loads or bending of the shaft. For example, if you mount an arm or a claw directly on the servo without any additional precautions, it is very likely that you will break the servo first time you drive into the wall with the arm extended (and this will inevitably happen).

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Configuring a Servo

FTC Docs·BSD 3-Clause

You will also want to add a servo to the configuration file. In this example, you are using a standard 180-degree servo.

Touch on the word Servos on the screen to display the **Servo

Configuration** screen.

Use the dropdown control to select "Servo" as the servo type for

port #0.

Use the touch pad to specify the name of the servo ("servoTest"

for this example) for port #0.

Press the Done button to complete the servo configuration. The

app should return to the previous screen.

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Connectors and Wires

Game Manual 0·CC BY-NC 4.0

There are many types of connectors for use in FTC®. Here are the most common connectors you will find on an FTC robot.

Anderson PowerPole — Anderson PowerPole is a connector used by AndyMark on their NeveRest motors. PowerPole connectors are extremely reliable, and are an excellent choice for high-usage connectors, such as batteries. There are adapters available to/from other systems. PowerPole connectors are crimped onto wires.

Warning: While OEM Anderson brand PowerPole connectors are extremely reliable, off-brand PowerPole connectors, commonly available on sites like Amazon, often have major reliability issues. When purchasing PowerPole connectors, only purchase ones specifically listed as Anderson brand.

Additionally, it is important to use crimpers specifically designed for PowerPole connectors. The IWISS iCrimp AP-11 (https://www.amazon.com/dp/B01MSQPTDS) crimpers are a solid choice at a reasonable price point on Amazon, though any quality crimpers specifically designed for PowerPole should work fine.

3.5mm Bullet — A power connector used on the goBILDA Yellow Jacket motors. Bullet connectors are soldered onto wires.

Warning: Due to the relatively strong holding force and the small size, it is common for teams to unplug these connectors by pulling on the wires instead of pulling on the connectors. This will cause fatigue and eventually failure. If you find yourself often operating these connectors, it is recommended to replace them with a connector that can be easily unplugged without damaging the connector, such as the JST VH or Anderson PowerPole connectors.

Dupont 0.1" (TJC8) — A small pinheader connector commonly used on servos and occasionally on some sensors. Dupont connectors are crimped onto wires.

Tip: Some vendors sell versions of the 3-pin female connector that are locking, which significantly improve the reliability of using servo extension wires. BackBayRC on Amazon sells servo extension wires with locking connectors (https://www.amazon.com/BackBayRC-Extension-Strands-Vehicles-bikes/dp/B0CXR2YBS4/); and Ferra Components sells both pre-made servo extension wires with locking connectors (https://ferracomponents.com/products/20awg-locking-servo-wire), and packs of locking connectors you can crimp yourself (https://ferracomponents.com/products/servo-locking-connector).

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Electronics and Motion Components

Game Manual 0·CC BY-NC 4.0

This chapter contains information on electric power and electronics of the robot, including information on wiring, batteries, motors, and control system.

Gauge — Wire gauge refers to the diameter of wire. AWG stands for American Wire Gauge, the general system used in the US. The larger the gauge number, the smaller the wire diameter. Generally, servo wires are 22 AWG and motor wires are 18 AWG.

Grounding Strap — The REV Grounding Strap is used to ground the metal frame of the robot to the XT30 port of the Expansion Hub. It is currently the only legal way to ground your robot.

USB Retention Mount — The USB Retention Mount, sold by REV, is a plastic part affixed to the Expansion Hub that relieves stress on the USB Mini port. This is especially important because if the USB cable is loose or disconnected, the robot phone cannot communicate with the Expansion Hub, causing a disconnect.

Note: For teams using an expansion hub, it is highly recommended for teams to purchase the USB retention mount.

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Robot Wiring Guide > Additional Resources

FTC Docs·BSD 3-Clause

Careful incorporation of the solutions and wire management tips in this guide should help ensure more robust electrical system performance and increase robot reliability.

Basic wiring instructions are also provided by REV Robotics (http://www.revrobotics.com/) on their DUO Control System support pages (https://docs.revrobotics.com/duo-control/menu/control-hub-gs/wiring-diagram).

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Controlling a Servo Blocks > Modifying Your Op Mode to Control a Servo

FTC Docs·BSD 3-Clause

Let's modify your op mode to add the logic required to control a servo motor. For this example, you will use the buttons on the Logitech F310 gamepad to control the position of the servo motor.

With a typical servo, you can specify a target position for the servo. The servo will turn its motor shaft to move to the target position, and then maintain that position, even if moderate forces are applied to try and disturb its position.

For the blocks Program & Manage server, you can specify a target position that ranges from 0 to 1 for a servo. A target position of 0 corresponds to zero degrees of rotation and a target position of 1 corresponds to 180 degrees of rotation for a typical servo motor.

In this example, you will use the colored buttons on the right side of the F310 controller to control the position of the servo. Initially, the op mode will move the servo to the midway position (90 degrees of its 180-degree range). Pushing the yellow "Y" button will move the servo to the zero-degree position. Pushing the blue "X" button or the red "B" button will move the servo to the 90-degree position. Pushing the green "A" button will move the servo to the 180-degree position.

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Robot Wiring Guide > Common Problems and Troubleshooting > Hub and Phone Communication Issues

FTC Docs·BSD 3-Clause

The signals that pass between the Android phone and the controllers are sensitive to interference. If a motor power wire or servo wire is routed next to a USB cable, it is possible to induce a stray signal that can lead to intermittent problems.

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Controlling a Servo Blocks

FTC Docs·BSD 3-Clause

In the section titled Creating an Op Mode with Blocks you learned how to use the Blocks Programming Tool to write an op mode that controls a 12V DC motor. In this section, you will learn how to write an op mode that controls a servo motor.

A servo motor is a special type of motor that is designed for precise motion. A typical servo motor has a limited range of motion.

In the figure below, a "standard scale" 180-degree servo is shown. This type of servo is popular with hobbyists and with FIRST Tech Challenge teams. This servo motor can rotate its shaft through a range of 180 degrees. Using an electronic module known as a servo controller you can write an op mode that will move a servo motor to a specific position. Once the motor reaches this target position, it will hold the position, even if external forces are applied to the shaft of the servo.

Servo motors are useful when you want to do precise movements (for example, sweep an area with a sensor to look for a target or move the control surfaces on a remotely controlled airplane).

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