Tachometer to analog output

Hi guys! I need some advice, I need to measure a motor's speed with a tachometer and get an analog output (voltage), but I need it to be proportionally inverse to the tachometer's frequency.
The higher the motor's speed, the lower the voltage output.
Is it possible with nano?
Thanks!!
-Carol.

Hi @carol_84

As the nano directly is not possible as it uses the Atmega328 which does not have the DCA circuit.
But using an external DCA receiving the information coming from the nano is possible.
You can also try doing this:

RV mineirin

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Sorry I haven't been clear enough!
I need a simple DC output, but inverse to the tachometer's frequency

Oh! Sorry I got it! OK
Thank you!

Hi
Yes I understand your need. A variable DC output on the output of an Atmega328 needs a circuit called a DAC.
D Digital
A Analog
C Converter

RV mineirin

Yes!! Now I got it! Thank you so much!!
I'm watching the link and it's for Leonardo's. Would it work with nano as well?

I believe so.
Just doing the circuit to be sure.
The difference is that Leonaardo uses ATmega32u4 chip, but the digital output is 5V as well.

RV mineirin

If you don't want to build a DAC circuit with the op amp or more simply with an RC low pass filter you can use an i2c DAC like and MCP4725 breakout board. They are inexpensive and readily available from many sources.

Your code will need to map the tachometer values to the inverse voltage.

Thank you!!

As an option to not use anything external, and with excellent performance is the ESP32.
It has 2 native DACs.

https://circuits4you.com/2018/12/31/esp32-dac-example/

RV - mineirin