Simple Tachometer code

[Gunner]

Firstly…

@Mad.macs

I’m kind of surprised there isn’t a function for measuring RPMs, or any other types of interrupts per second already written into Blynk.

Why is this Blynk’s responsibility? Reading such impulses has nothing to do with Blynk.

Rather, one would use already existing and varying interrupt & counter code, along with whatever formulas needed to break it down into RPM or RPS, etc., as used in many Arduino projects floating around the web. See here for example - Arduino Playground - ReadingRPM

Blynk is predominantly an IoT GUI, thus can already easily be used to take the resulting values from aforementioned code functions and display it across your IoT needs.

Secondly…

@Mad.macs

attachInterrupt(digitalPinToInterrupt(pin), speedCalc, FALLING);

@Mad.macs

void speedCalc() {
  elapsed = micros() - start;
  start = micros();

 //RPM = ((120 * (1000000 / elapsed)) / numOfCyl); //MS to RPM +-30RPM Res
 RPM = ((12*(10,000,000/elapsed)) /numOfCyl); //uS  +- 3RPM resolution
}

I would recommend keeping the function called from the interrupt as lean as possible… just a simple counter increment will do.

Then using a timer controlled function, you can call up the counter value, run your calculations for the final displayable variable, send it to Blynk’s App, clear the counter and carry on.

For example on the final stage…

Tachometer using Image Widget

OK, while assisting another topic, I got hooked again on a Project Idea In the past I have played with a modified Nextion project of someone else’s, containing 209 images of a tachometer with the needle at differing positions from start to finish. [0] [104] [208] NOTE: I did NOT make these images, but I did have to resize/number each one to fit my little 2.4" nextion… and that was tedious. Anyhow, that was Nextion… but this is Blynk!! So the other topic was the question of image li…