TECHNICAL SUPPORT
Published 2026-04-13
Adjusting theservoangle range is a common need when aservodoes not rotate to the expected position. In many standardservos, the default angle range is 0 to 180 degrees. However, due to mechanical tolerances or signal differences, a servo may only move from 10 to 170 degrees when given standard pulse widths. This guide explains how to accurately adjust the angle range of a servo, focusing on the pulse width modulation (PWM) signal, mechanical limits, and calibration steps. All methods are based on common, brand‑independent practices used in robotics and DIY projects.
A standard servo’s angle is determined by the width of a PWM signal. Typically:
1.5 ms pulse→ neutral position (90 degrees)
1.0 ms pulse→ 0 degrees
2.0 ms pulse→ 180 degrees
These values are common for many servos, but the actual angle for a given pulse width can vary between individual units. If a servo does not reach the full 0‑180° range, you need to adjust the pulse width limits sent to it.
There are two main methods:
Software adjustment– change the PWM pulse width limits in your code or controller. This is the safest and most common method.
Mechanical adjustment– modify the servo’s internal potentiometer or physical stops. This is more advanced and risks damaging the servo.
For most users,software adjustmentis the recommended approach.
The most direct way to adjust the angle range is to redefine the minimum and maximum pulse widths that correspond to 0° and 180°.
1. Find the current pulse width for 0°
Send a pulse width slightly below 1.0 ms (e.g., 0.9 ms) and gradually increase until the servo just stops moving at its minimum angle. Record that value as yourminPulse.
2. Find the current pulse width for 180°
Send a pulse width slightly above 2.0 ms (e.g., 2.1 ms) and gradually decrease until the servo just stops at its maximum angle. Record that value as yourmaxPulse.
3. Map your desired angle to the new pulse range
Use linear mapping. For example, if you want 0° to correspond to 0.6 ms and 180° to 2.4 ms,any angleimaps to:
pulse = minPulse + (θ / 180) * (maxPulse - minPulse)
4. Update your servo control code
Replace the default 1.0‑2.0 ms range with your measuredminPulseandmaxPulse.
Practical example:
A common servo (no brand) only moves from 5° to 175° when sent 1.0‑2.0 ms pulses. After testing, you find that 0.65 ms gives 0° and 2.35 ms gives 180°. By updating your code to use 0.65‑2.35 ms as the full range, the servo now reaches true 0° and 180°.
Mechanical adjustment is only needed if:
The servo cannot reach the desired angle even after extending the PWM limits to the controller’s maximum (e.g., 0.5‑2.5 ms).
You need to physically increase the rotation beyond the servo’s design (e.g., converting a 180° servo to 270°).
1. Open the servo case carefully.
2. Locate the feedback potentiometer. Its rotation range is often limited by a mechanical stop.
3. Remove or file down the stop to allow more rotation.
4. Recalibrate the zero position by adjusting the potentiometer.
5. Reassemble and test with a narrower PWM range (e.g., 0.5‑2.5 ms) to avoid overdriving.
Warning:This voids any warranty and can break the servo if not done precisely. Only attempt if you accept the risks.
Never exceed 2.5 ms or go below 0.5 ms for more than a few seconds – this can overheat and damage the servo.
Always test with small steps when finding new pulse limits.
Remove any load from the servo during calibration.
Use a current‑limited power supply (e.g., 1A max for standard servos) during testing to prevent damage.
Document your calibrated values for each servo, as they can vary even among identical models.
To adjust a servo’s angle range correctly:
1. First, always try software adjustment – measure the actual pulse widths needed for 0° and 180°, then update your control code.
2. Only consider mechanical modification if software limits are insufficient and you are prepared for the risks.
3. Test systematically – change one variable at a time, and keep a log of pulse width vs. actual angle.
4. Stay within safe pulse limits – 0.5 ms to 2.5 ms is the absolute maximum for most standard servos.
Key takeaway: The angle range is not fixed – it is defined by the PWM signal you send. By carefully measuring and adjusting the pulse width limits, you can make any servo reach its true mechanical endpoints. Always start with software calibration, as it is safe, reversible, and effective for 95% of use cases.
Update Time：2026-04-13
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