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Published 2026-04-12
A 360-degreeservo, also known as a continuous rotationservo, does not stop at specific angles like a standardservo. Instead, it spins continuously in either direction, and its rotation speed is fully adjustable. This article explains the precise method to control the speed of a 360-degree servo using common hardware (e.g., an Arduino or a basic PWM signal generator) and real-world examples. No brand names are mentioned, only general principles that apply across all standard continuous rotation servos.
Unlike standard servos that interpret a 1.5 ms pulse as the “center” (stop) position, a 360-degree servo treats the same 1.5 ms pulse asfull stop. When you send a pulse width longer than 1.5 ms (typically 1.6 ms to 2.0 ms), the servo rotates in one direction (e.g., clockwise) at a speed proportional to the deviation. Similarly, a pulse width shorter than 1.5 ms (typically 1.4 ms to 1.0 ms) causes rotation in the opposite direction (e.g., counterclockwise). The further the pulse width is from 1.5 ms, the faster the rotation.
Key point:Speed is directly controlled by how much you “move away” from the 1.5 ms neutral pulse. The range is usually between 1.0 ms and 2.0 ms, with 1.5 ms being stop.
Most 360-degree servos operate with a pulse cycle of 20 ms (50 Hz). The speed control range is between 1.0 ms (full speed one direction) and 2.0 ms (full speed the opposite direction), with 1.5 ms as stop. However, some servos may have slightly different limits (e.g., 0.9 ms to 2.1 ms). Always consult your servo’s datasheet or perform a simple test as described below.
You need a PWM (Pulse Width Modulation) signal with a fixed frequency (typically 50 Hz) and variable pulse width. This can be done using:
A common microcontroller board (e.g., Arduino Uno, but any board works)
A dedicated servo tester (standalone device)
A function generator
For example, using a generic microcontroller code (pseudo-code):
Set PWM frequency = 50 Hz For stop: set pulse width = 1500 microseconds (1.5 ms) For slow clockwise: set pulse width = 1600 µs For faster clockwise: set pulse width = 1700 µs ... up to 2000 µs For slow counterclockwise: set pulse width = 1400 µs For faster counterclockwise: set pulse width = 1300 µs ... down to 1000 µsThe relationship between pulse width deviation and rotation speed is approximately linear. To achieve a desired speed, calculate the required pulse width as:
Pulse width (µs) = 1500 ± (K × desired_speed), where K is a constant specific to your servo (typically between 300 and 500 µs for full speed).
Practical example from a common robotics project:
A hobbyist needed their servo to turn a wheel at exactly 30 RPM for a line-following robot. Using a 1.65 ms pulse (150 µs above neutral), they measured 30 RPM. When they increased to 1.75 ms (250 µs above neutral), the speed increased to 55 RPM. This shows the direct proportional control.
Never assume the factory neutral point is exactly 1.5 ms. Many servos have a slight offset. To find true stop:
Send a 1.5 ms pulse. If the servo still creeps, adjust pulse width up or down in 10 µs steps until it stops completely. That is your true neutral.
Then, send pulses increasingly farther from neutral to map the speed range.
The speed of a 360-degree servo is directly proportional to the absolute difference between the applied pulse width and the servo’s neutral stop pulse (typically 1.5 ms). To increase speed, move the pulse width further from neutral. To decrease speed, move it closer to neutral. Direction is determined by whether the pulse is longer (one way) or shorter (the opposite way) than neutral.
1. Always power the servo from a dedicated external power source (4.8V–6.0V) capable of supplying at least 1A per servo. Do not rely on the microcontroller’s 5V pin, as current draw during speed changes can cause brownouts and erratic behavior.
2. Calibrate neutral before every project – use a simple test sketch that sweeps pulses from 1.4 ms to 1.6 ms in 10 µs steps. Mark the value where rotation stops completely. That value is your true neutral.
3. Use a separate servo tester for quick manual speed adjustments without coding. This is especially useful during mechanical prototyping.
4. For precise speed control (e.g., conveyor belts, robot wheels), add an encoder to create a closed-loop system. Open-loop control works for many applications, but load variations will affect actual speed.
5. Document your pulse-width-to-speed mapping – for each servo model you use, create a simple table:
Pulse = 1.50 ms → 0 RPM (stop)
Pulse = 1.55 ms → 10 RPM CW
Pulse = 1.60 ms → 25 RPM CW
... up to 2.00 ms → max RPM CW
And similarly for counterclockwise.
By following this guide, you can achieve smooth, linear, and repeatable speed control for any 360-degree servo in your robotics, automation, or hobby projects. Always test your specific servo’s response, as manufacturing tolerances cause slight variations.
Update Time：2026-04-12
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