I dislike the cheap servo testers from AliExpress with a single button. When power is lost, they often switch modes automatically, which can cause damage. For example, if the tester switches to auto mode, it might trigger a full rotation cycle on the servo instead of staying in manual mode.

To solve this problem, I designed a servo tester with fixed modes, selectable via dedicated buttons.

Features

- Neutral Mode: Sets the servo to 90 degrees.
- Manual Mode: Allows you to configure the servo to a specific angle of your choice.
- Auto Mode: Cycles the servo between the minimum and maximum values at a set speed.

The device is operated with a rotary encoder. Pressing the encoder button cycles through the adjustable values, while rotating it adjusts the selected value.

It is powered via USB-C and includes a switch to turn the servo on or off. The values are stored in the device.

Required Parts
1x ESP32-C3
2x 1kΩ resistors
3x small switches
11x 8mm M3 screws
1x rotary encoder (EC11, 15mm shaft)
1x 1µF capacitor
1x I2C SSD1306 0.91-inch OLED display
Additional wires and a soldering iron

The ESP32-C3 code is in the .zip file.