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  1. I have connected pin 3 to a DC motor and using analogWrite and DigitalWrite to try making it start. However, nothing happens.

  2. If I try to move the pin from pin 3 to 5V or 3.3V the motor starts.

Q: What could be the problem since it does not start using pin 3 (or others). I am using HIGH on digitalWrite and 255 on analogWrite.

Thanks for any help!

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  • There is a big PDF tutorial that goes with this kit. Did you download it? Did you read the chapter on controlling a motor? Jul 28 '19 at 9:29
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The Tutorial.pdf document that describes the components in the kit does not tell you what the current draw of the motor is. Chapter 10 has 2 tutorials on how to use the motor with a relay or L293D IC. This suggests to me that the motor draws a lot more current than a digital output can provide.

The tutorial using the L293D gives you the ability to vary the speed of the motor using PWM, so it would be a good place to start.

Hopefully pin 3 was not damaged by the excess current flow when the motor was attempted to be powered from it.

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The digital/analog pins cannot directly source enough current to run a motor. Use the pin to control a switching device like a mosfet which then controls current flow to the motor.

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You should read up on controlling motors from digital circuits and follow a tutorial until you understand the "gotchas".

You have to be careful with the pins on an Arduino and not trying to draw too much current from them. A motor very likely needs several times more current than an Arduino digital pin can provide (you should keep the current draw on an Arduino pin ≤20 mA. Your motor might well draw 10 times that much. You might have damaged or destroyed the pin you used.

Secondly, motors use inductive coils (electromagnets). Inductors have an effect called "back EMF" that causes a reverse surge of current when you remove power from them. That will also fry whatever solid state component is driving the inductor. (The Arduino pin if you're trying to drive the inductor directly, or a transistor if you're switching the current to the inductor using a transistor.) You need a "flyback diode" on the inductor to protect the circuit that drives it.

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