PicoPorch Motor Controller

27 May 2024

Intro

I finally assembled the PicoPorch motor controller. This blog shows it in operation using manual switches to control motor direction and limit switches to prevent over rotation in either direction.

Motor Controller CCA

You can see 2 places where I substituted SOT23 transistors for larger transistors. Fortunately this motor does not require high current.

Schematic

This bi-directional DC motor controller features a shoot-through protected H-bridge with directional limit switches. For an explanation of its operation see the video below. I wanted to perform both the shoot-through protection and limit switch functions in hardware for maximum safety.

Motor Controller Video Demo

Discussion

It is nice to get the motor controller working. Even though one of the transistors did not arrive, I was able to substitute some I had in stock. They are lower power devices, but this motor only draws 15 mA so power is not an issue.

This demo means that both custom PCBs are functional, which is a key milestone in the project.

There is still some mechanical design to get the limit switches to activate at the correct positions and the stands to mount all the apparatus need to be designed and built. Although it is still a significant amount of work, the remaining work mostly involves mechanical tinkering and assembly rather than risky design.

There is also some firmware to be developed, but a fully functional system should be fairly straightforward. I might add some complexity as a stretch goal, if there is time.

Next up:

Build more cables
Program the Pico to control the motor
Wire up the system and test it.
Design and build the motor controller case mounting stand
Design and build the limit switch mounts and triggers
Design and build the rain guard for the motor mechanism
Test he system in the wild (extreme environment)
Make more videos and blogs