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KlausMu / esp32-fan-controller

ESP32 fan controller with temperature sensor and MQTT
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incorrect data #8

Closed mkeyno closed 2 years ago

mkeyno commented 2 years ago

Hi thanks for sharing the code, I've tried to use your code and pair of two PNP proximity sensors to measure 2 motor speeds, but I find if I decrease the tachoUpdateCycle time , it shows the incorrect speeds, I was thinking it may be a better idea to use a time span between the pulses instead of counting the pulses

KlausMu commented 2 years ago

Oh, it seems there is a bug in the code. tachoUpdateCycle = 1000 means you are counting the pulses for one second. Afterwards, when calculating rpm (revolutions per minute) out of the counted pulses, you have to take into account how long you did the measurement. So probably instead of last_rpm = counter_rpm * (60 / numberOfInterrupsInOneSingleRotation); it should be last_rpm = counter_rpm * (60 / numberOfInterrupsInOneSingleRotation) * (1000 / tachoUpdateCycle); Could you please try this with different tachoUpdateCycles? Should always result to the same rpm.

In case it is not clear: the pulses are counted continuously. tachoUpdateCycle only means how often you calculate the rpm out of the counted pulses and reset the pulse counter counter_rpm. I think this is the best way to do it. Measuring the time span leads to other problems, e.g. if the time span always differs a litte bit. The interrupt routine has to be as simple as possible in order to take as less time as possible, and there is nothing simpler than counter_rpm++;

KlausMu commented 2 years ago

I did this change in the code and commited it.