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Project Notes

#695 ATtiny PMW Motor Control

Variable speed PWM motor control with an ATtiny85.



Demonstrates using a PWM signal to control a DC motor, hence its speed.

PMW is generated by an ATtiny85 with the duty cycle set based on reading a variable resistor.

The PWM signal switches a low-side n-channel FET to control the motor.

A fly-back diode is placed across the motor to drain any voltage spike as the motor load is switched

In the demonstration circuit, the ATtiny85 and motor are powered from the same 5V supply. Some hefty capacitors are added to smooth the supply and prevent the motor from disturbing the power supply to the microprocessor.

The following scope trace shows the PWM out (CH1 Yellow) compared to the variable resistor input voltage (CH2 Blue):


Circuit Design




Credits and References

Project Source on GitHub Project Gallery Return to the LEAP Catalog

This page is a web-friendly rendering of my project notes shared in the LEAP GitHub repository.

LEAP is just my personal collection of projects. Two main themes have emerged in recent years, sometimes combined:

  • electronics - usually involving an Arduino or other microprocessor in one way or another. Some are full-blown projects, while many are trivial breadboard experiments, intended to learn and explore something interesting
  • scale modelling - I caught the bug after deciding to build a Harrier during covid to demonstrate an electronic jet engine simulation. Let the fun begin..
To be honest, I haven't quite figured out if these two interests belong in the same GitHub repo or not. But for now - they are all here!

Projects are often inspired by things found wild on the net, or ideas from the many great electronics and scale modelling podcasts and YouTube channels. Feel free to borrow liberally, and if you spot any issues do let me know (or send a PR!). See the individual projects for credits where due.