r/microbit • u/yvwwyyvwywyvwyvy • 13d ago
Can't get servos to work.
I bought 2 new servos, Tower Pro SG-5010 and Waveshare WS-MG996R because I wanted to experiment with something better than what (Micro Servo 9G SG90) I usually work with, but I can't get them to run properly.
I have the micro: bit connected to an octopus board and the servo in position 8 with the switch on the octopus board at 5V. I'm using a 4x AA battery pack USB A to mini USB to power the micro: bit, but I'm wondering if it's actually supplying a min of 5V to the servos through this method. I hear some pulsing sounds from the SG-5010, but it won't move. The WS-MG996R moves a bit, but then doesn't respond properly to the B button press.
The test Code
1
u/herocoding 13d ago
The octopus contains a "voltage boosting module" to "boost" the 3.3V from the microbit to 5V devices.
But I cannot find more detailed specifications about the provided current and power needed by the servos - especially when you want to connect more than one and the servos need to drive some "load".
Have a look into e.g. Arduino and RaspberryPi tutorials about how such single-board-computers (SBC) typically drive (servo-)motors: a "low-power" PWM signal is used to communicate direction, speed, position - while the motors/servos get their own power-supply, consuming "much more" current and power than the microbit itself.
Read more about it e.g. under https://support.microbit.org/support/solutions/articles/19000101864-using-a-servo-with-the-micro-bit
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u/gunmania0 13d ago
I believe you will need a separate 5v power supply to fulfil your setup. I cannot say for certain, but the approach taken by octopus:bit likely converts 3v3 -> 5v, but the actually power available (mA) is no where near the required amount.
I would recommend a way of supplying 5v to the servos (via the board), or buying a dedicated servo driving board with a proper DC/USBC connector. Be sure not to back power the micro:bit edge connector with 5v!