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I've been learning Arduino for a while, and for my next project I'm attempting to build a drone. When I tested the motors that I purchased before, they seemed to work fine using the PWM pins and I saw no need for a motor driver.

However, now, a week later, the PWM pins are much too weak. I've set them to OUTPUT mode and HIGH.

Should the basic digital output pins be able to run fairly small drone motors like mine?

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    "Should the basic digital output pins be able to run fairly small drone motors like mine?" - lol, no, I don't think so. Before powering any electronic component, you should make really sure, that you don't exceed current limits. I guess you haven't checked, how much current your motors draw? It will save you a lot of frustration to be very careful and always check current limits first. And ocrdu is also right with the flyback diode.
    – chrisl
    Jan 18, 2021 at 20:41

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The Absolute Maximum is 40 mA per pin, but you shouldn't go even close to that; max. 20 mA per pin is about where you want to be. Total current (all pins) shouldn't exceed 200 mA.

Only you know what current your "fairly small" motors pull, but you may have fried a few IO pins.

Also, you need flyback (or maybe bidirectional TVS) diodes and a few capacitors on your motors to keep noise and inductive kick-back away from your pins. Motor driver modules often have these installed, but your Arduino pins don't. Inductive kick-back can easily kill IO pins also.

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Time to purchase another Arduino or use the other pins. Before you connect the new one you need to get a method of driving the motors. Keep in mind they are inductive and will reverse polarity and kick back a voltage that will keep rising until adsorbed. If you will be reversing them pick a MOSFET bridge to drive them. If just on/off/PWM pick a Logic rated avalanche rated N-Channel MOSFET with a high enough voltage and current rating. If your Arduino is 3V3 you need to be sure the gate will be on at about 2.5V. Connect all the grounds together and connect the source of the MOSFET to ground as well. Place something in the 25-50 Ohm resistor from the Arduino pin to the Gate of the MOSFET. Then connect the motor to the drain and the appropriate + supply. No diodes need as it has one built into the MOSFET designed for this. If you want the MOSFET off place something like a 10K resistor from the Arduino pin to ground. Remember a Power Supply the Arduino is NOT! While you are waiting on the parts go through several tutorials on the arduino and motors. There are some good ones and some not so good.

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