Servo
Controlling Continuous Servo with ESP32
What is the Continuous Servo?
A servo modified for full continuous rotation rather than fixed-angle positioning, useful as a simple speed-controlled wheel drive.
Specifications
| Operating voltage | 4.8V - 6V DC (5V typical) |
| Control signal | PWM, 50Hz, 1ms-2ms pulse width — but the pulse now sets speed and direction, not angle |
| Neutral point | ~1.5ms pulse = stopped; shorter/longer pulses spin one way or the other, further from 1.5ms = faster |
| Positioning | None — fully open-loop, no feedback on shaft angle, only continuous rotation |
| Typical no-load speed | ~50-60 RPM, varies by donor servo and how it was modified |
| Weight | ~9g-55g depending on donor servo (SG90-based vs MG996R-based) |
Continuous Servo Pinout
| Pin | Name | Description |
|---|---|---|
| 1 | GND | Ground — usually the brown or black wire |
| 2 | VCC | Power, 4.8V-6V DC — usually the red wire |
| 3 | Signal | PWM control input — usually the orange or yellow wire |
Every unit's stop point drifts slightly from the textbook 1.5ms. Sweep 1.3ms-1.7ms in code once and hard-code the value that actually stops your specific servo.
Setting Up Continuous Servo with ESP32
Library
Servo by Arduino
Bundled with the Arduino IDE core
Wiring
| Component pin | ESP32 pin | Note |
|---|---|---|
| VCC | 5V (VIN, if available on your ESP32 board) | Use an external 5V supply if the board resets when the servo moves |
| GND | GND | — |
| Signal | GPIO18 | Any PWM-capable GPIO works |
Example code
Unlike a positional servo, write() here sets speed and direction, not an angle -- 90 is stop, values above/below rotate at a speed proportional to distance from 90. The exact stop point varies per unit and may need trimming (e.g. write(88)).
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