Arduino Frequency Counter

Hi David,

Thats a very good point, thank you for letting me know. I’ll sift through the data sheets and see which one fits best. Any recommendations, given my pulse width and amplitude?


Hi Aamer @aab5544,

As long as you use an asynchronous interrupt to catch the pulse and the pulses are not more frequent than every 10 microseconds or so (which would mean a maximum pulse rate of 100 KHz), I would think pretty much any of them would be sufficient to not miss any pulses. I believe the Uno is the slowest, at a 16 MHz clock rate.

Regarding logic High threshold voltage, those running on 3.3V will typically have a lower Vin-high minimum voltage threshold than those running on 5V. As an example, the ATSAMD21G18A on the ARDUINO NANO 33 IOT claims that if running above Vdd of 2.7V, the logic High input threshold voltage is 0.55 x Vdd, so 1.815V with Vdd of 3.3V. However, I would shoot for 0.7 x Vdd to be safe.

From an ease-of-implementation standpoint, the Uno is probably still the most straight-forward in terms of minimizing complexity. It has the fewest features, and is therefore the least complex part to learn. It’s a trade-off that you’ll have to consider.

Hi Aamer @aab5544,

Thank you for your thoughtful explanation.
That clarified your setup a lot.
As you have +2.5V positive supply for the opamp, that explains the pulse amplitude that you are getting. The LT1226’s output saturates to the maximum swing, which is roughly 2 volts below positive rail. If you could replace the op-amp to something having rail-to-rail output, and tie the opamp’s positive supply to the Arduino’s supply (3.3V, 5V?) then you’ll get enough swing for digital quantization.
Be careful with the alpha particles :slight_smile:
Cheers, heke