Custom-Built Servo Tester

November 23, 2012

When evaluating and repairing servos you need a good servo tester. It needs to be portable, have an easy-to-read screen, have lots of adjustable parameters, and it should have an internal battery while still allowing an external power source. There are several testers on the market but none of them did everything I wanted. So I made my own servo tester. This was my first real project with the STM32F4 and it turned out great. I later ported it to the STM32F0 (since the F4 is overkill for this task) and it performed just as well.

There are four modes: sweep, three positions, two positions, or one position. The sweep mode is useful when checking for damaged (but not stripped) gears. The three-position and two-position modes are great for testing the motor -- it should be warm, not hot, after half an hour of cycling. Lastly, the one-position mode is helpful when setting up a new model.

Each mode has several parameters that can be adjusted. The number of cycles can be limited. The framerate (specified as a period) can be changed. A blinking underline specifies which parameter is currently selected. The buttons on the top adjust the parameter's value, while the buttons on the front change parameters. The rest should be obvious:

It was a fun project. Download the source code for the STM32F4 or STM32F0. See the README file in each archive for details.