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[Reply #30 on:]

I am concerned that the atmega328p datasheet provides (as far as I can tell) no data on the speed of the analog comparator, so there is no telling whether it is fast enough for this application.

I was concerned about that as well, but I'll try and report back.

As far as the circuit itself is concerned, I understand how it works and will use a similar setup. I know there are other ways with less hardware but this project is not intended for sale or anything, mainly just to use Atmega328 features I haven't used before(like the comparator) and understand how they work. And to have a working ESR-meter in the end

@dhenry
I'd be interested in the code and schematic as well, but I'll implement it the other way.

[Reply #31 on:]

When you are done, come back and we can compare notes then.

[Reply #32 on:]

When you are done, come back and we can compare notes then.

You know the schematic, and the code is pretty easy

Code:

ISR(TIMER2_COMPA_vect){                        // every 500µs
  bitWrite(PORTD, 3, 0);                          // Disable discharge
  bitWrite(PORTD, measurementRange, 0); // Pulse
  delayMicroseconds(7);                           // The pulse width should be around 8µs
  bitWrite(PORTD, measurementRange, 1); // Stops the pulse
  bitWrite(PORTD, 3, 1);                         // Enable discharge
}

ISR(ANALOG_COMP_vect){ // Comparator interrupt
  compareCounter++;
}

In the lowest range, every pulse is 10mΩ. In the middle range 100mΩ and 1Ω in the high range.

[Reply #33 on:]

What about your code and setup?

[Reply #34 on:]

In the lowest range, every pulse is 10mΩ. In the middle range 100mΩ and 1Ω in the high range.

Great. Please let us know how that's working out for you.