Servo Motor Pin Diagram

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Reference wiring guide for the standard 3-wire hobby servo connector covering power, ground, and PWM signal pin assignments.

A standard hobby servo motor uses a 3-wire connector with the following pin assignments: Power (V+), Ground (GND), and Signal (PWM). This pinout is consistent across the vast majority of RC and hobby-grade servos regardless of manufacturer, though connector housing colours and pin positions vary between brands.

Pin 1 — Signal (PWM): The control signal wire, most commonly yellow, white, or orange. It carries a 50 Hz pulse-width modulated signal from the controller. The signal voltage is typically 3.3 V or 5 V logic level, though some servos accept either. The pulse width determines servo position: a 1 ms pulse commands approximately 0° (full left), a 1.5 ms pulse commands the neutral or centre position (approximately 90°), and a 2 ms pulse commands approximately 180° (full right). The servo ignores signal amplitude and responds only to pulse width.

Pin 2 — Power (V+): Typically the centre wire, often red. Operating voltage for most standard hobby servos is 4.8 V to 6.0 V. Digital servos may accept up to 7.4 V. Do not draw servo power from a microcontroller's 3.3 V or 5 V regulator pin — servos draw significant current (500 mA to 2 A stall) that will reset or damage most microcontrollers.

Pin 3 — Ground (GND): The reference ground, typically black or brown. Must share a common ground reference with the signal source (microcontroller, receiver, or servo driver). Without a shared ground, the PWM signal cannot be interpreted correctly.

Connector colour coding (common convention): Signal = yellow/white/orange; Power = red; Ground = black/brown. Always verify against the specific servo's datasheet as exceptions exist.

The 50 Hz PWM standard (20 ms frame, 1–2 ms pulse) is a widely adopted convention derived from early RC systems and is supported by all mainstream microcontroller PWM libraries. This is an illustrative reference diagram. Verify signal voltage and supply voltage compatibility before connecting any servo to a controller.

How to wire servo motor pin diagram

Identify the three wires on the servo connector Locate the 3-pin JR/Futaba-style connector. Identify the signal wire (orange/yellow/white), power wire (red), and ground wire (brown/black). Cross-reference with the servo's datasheet if colours are non-standard.
Connect ground to a common reference Connect the servo's GND wire to both the negative terminal of the servo power supply and the GND pin of the microcontroller or receiver. A shared ground reference is essential for correct signal interpretation.
Connect the power supply Connect the red (V+) wire to a dedicated power supply capable of delivering sufficient current. Use 4.8 V to 6.0 V for standard servos, or up to 7.4 V for high-voltage digital servos. Do not use the microcontroller's onboard 5 V regulator for this purpose.
Connect the signal wire to a PWM-capable output Connect the signal wire to a hardware PWM output pin on the microcontroller, servo driver IC, or RC receiver. Configure the PWM output for 50 Hz with pulse width adjustable between 1 ms and 2 ms.
Verify signal voltage compatibility Confirm that the servo's signal input accepts the controller's logic voltage (3.3 V or 5 V). Some servos require a 5 V signal even if powered at 6 V. Use a logic level shifter if the controller is 3.3 V and the servo requires 5 V signal.
Test with known pulse widths before full deployment Send a 1.5 ms pulse to command the neutral position. Verify the servo arm centres. Then test 1 ms and 2 ms to verify full travel range. Note actual mechanical end-stops may differ from the 1–2 ms theoretical limits.

Specifications

Signal type	PWM (pulse-width modulated)
PWM frequency	50 Hz (20 ms period)
Pulse width — full left / 0°	Approximately 1 ms
Pulse width — centre / neutral	Approximately 1.5 ms
Pulse width — full right / 180°	Approximately 2 ms
Signal voltage (logic level)	3.3 V or 5 V (verify per servo datasheet)
Operating voltage (standard servos)	4.8 V – 6.0 V
Typical stall current	500 mA – 2 A (varies significantly by servo size)

Safety warnings

Never draw servo power from a microcontroller's onboard voltage regulator pin. Servo stall current (up to 2 A or more) can damage the regulator or reset the microcontroller.
Always include a decoupling capacitor (at least 100 µF electrolytic) across the servo power supply terminals to prevent voltage spikes from corrupting the microcontroller.
Servos can generate significant torque and may cause injury or damage if connected to mechanical loads without appropriate mechanical stops and load testing.
Verify signal wire voltage compatibility before connecting. Applying 5 V signal to a 3.3 V-only microcontroller GPIO can damage the microcontroller.
This diagram is an illustrative reference only. Always verify pinout against the specific servo's manufacturer datasheet before connecting.

Tools needed

Digital multimeter (voltage and continuity measurement)
Oscilloscope or logic analyser (to verify PWM signal timing)
Regulated bench power supply (5 V or 6 V, ≥2 A)
Breadboard or prototype PCB for initial testing
Servo driver or PWM library-compatible microcontroller
Wire strippers and jumper wires

Common mistakes

Powering the servo from the microcontroller's 5 V pin, causing voltage brownouts or microcontroller resets under load.
Omitting a shared ground between the servo supply and the microcontroller, resulting in erratic or no servo response to PWM signals.
Setting PWM frequency too high (e.g. 100–300 Hz) instead of 50 Hz, which causes standard analogue servos to jitter or behave erratically.
Assuming wire colour is universally standardised and not verifying against the servo's datasheet.
Omitting a decoupling capacitor on the servo power rail, allowing inductive switching spikes to corrupt microcontroller operation.

Troubleshooting

Servo jitters continuously even with no commanded movement: Cause: Electrical noise on signal wire, incorrect PWM frequency, or insufficient power supply decoupling Fix: Add 100 µF decoupling capacitor across servo power terminals. Verify PWM frequency is exactly 50 Hz. Add a 10 kΩ pull-down resistor on the signal line and use a short, direct signal wire routing.
Servo does not respond to PWM signal at all: Cause: Missing shared ground reference, incorrect signal voltage, or signal wire disconnected Fix: Verify GND is common between servo supply and signal source. Measure PWM signal with an oscilloscope to confirm 50 Hz, 1–2 ms pulses are present at the servo signal pin.
Servo moves to one extreme and stops, or only moves to centre: Cause: Pulse width outside servo's acceptable range, or PWM not configured for the correct period Fix: Recalibrate pulse width values. Most hobby servos respond to 1 ms–2 ms, but some require 0.5 ms–2.5 ms or are trimmed differently. Refer to the servo's datasheet for exact range.

Frequently asked questions

What PWM frequency and pulse width does a standard hobby servo use?

Standard hobby servos expect a 50 Hz signal (20 ms period). Pulse width of approximately 1 ms commands one end of travel, 1.5 ms commands the centre (neutral) position, and 2 ms commands the other end of travel. Exact end-stop behaviour varies by servo model.

Can I power a servo directly from an Arduino 5V pin?

Not recommended for most servos. Arduino 5 V pins are typically limited to 200–500 mA via the onboard regulator. Most servos draw 500 mA to 2 A at stall. Use an independent 5 V or 6 V supply with a shared GND connection to the microcontroller.

What does the signal wire colour indicate?

The most common convention is: orange or yellow = signal, red = power (V+), brown or black = ground. However, this is not a universal standard — always verify the pinout in the specific servo's datasheet before connecting.

What happens if the PWM signal is lost or disconnected?

Behaviour varies by servo. Most standard servos will hold their last commanded position for a brief period, then may drift or become free-spinning. Some digital servos have configurable fail-safe positions. In safety-critical applications, implement a hardware fail-safe.

What is the difference between an analogue and a digital servo in terms of pinout?

The 3-wire pinout (V+, GND, Signal) is identical for both analogue and digital servos. Digital servos differ internally — they use a microprocessor to process the PWM signal at a higher update rate, providing faster response and better torque holding, but the connector is the same.

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