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I have a Raspberry Pi 3 with the corresponding power supply and I'm looking for a motor that can be used without battery or external motor. The final goal would be to activate a motor in both directions (in order to act on a wall switch1).

For example, can a motor be powered by an USB port and controlled with the USB link or GPIO? It would ease connections.

Please share names or references of these motors if they exist.

(1 I know that I can replace the wall switch with a electric relay but I'm not considering this solution at the moment)

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    Probably not. Motors have a lot of issues back-feeding and high current draws especially when starting up or changing direction. Without additional circuitry these would damage the pins on the GPIO. USB would also need additional circuitry to decode the commands, so there would be some kind of driver board either way.
    – Ron Beyer
    Aug 4, 2016 at 14:40
  • @RonBeyer Thanks for your comment. USB fans exist, so power supply should not be a problem with USB. But like you said, there should be something to control a USB-powered motor.
    – A.L
    Aug 4, 2016 at 14:45
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    Yes, some fans exist, and if you want the motor to just "run" then you can connect it directly to the 5V supply (if its a small motor). If you need to start/stop/reverse/speed, then there has to be some command processing. It also depends on the size of the motor and the load you are driving.
    – Ron Beyer
    Aug 4, 2016 at 14:47
  • @RonBeyer I forgot some explanations, I added my needs in the question.
    – A.L
    Aug 4, 2016 at 14:57
  • A small-meduim (continuous rotation) servo is probably sufficient to turn a dimmer switch, if that is what you are talking about, it which case it can be powered and controlled directly from the Pi. handyboard.com/hb/faq/hardware-faqs/dc-vs-servo (note the description there is of normal servos that can be positioned in a 180° arc; a "continuous rotation" servo will turn around and around). It may also be better suited to the very low RPMs this presumably involves.
    – goldilocks ♦
    Aug 4, 2016 at 16:44

1 Answer 1

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Probbably your best option is to get the Explorer HAT Pro from Pimoroni (https://shop.pimoroni.com/products/explorer-hat) or The Pi Hut (https://thepihut.com/collections/raspberry-pi-hats/products/explorer-hat-pro) and some micro metal gear motors (https://shop.pimoroni.com/products/micro-metal-gearmotor-extended-back-shaft).

Explorer HAT Pro

The HAT plugs directly into the Pi via the GPIO pins. The motors then plug into the HAT's 'motor' pins (shown on the right above). You will need to solder the wires onto the motors.

The HAT has two H-Bridge motor drivers which provide 200mA at 5V per channel, allowing you to control two of these motors. They won't be the fastest or most torque-y motors you'll ever find, but if you want basic movement without a separate power supply, this will do nicely.

Micro Metal Gear Motors

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  • I have abandoned the idea, so I won't be able to try your solution, but your answer is very useful so I accept it. Thanks.
    – A.L
    Aug 5, 2016 at 13:22

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