// read RPM
volatile int rpmcount = 0;//see
http://arduino.cc/en/Reference/Volatileint rpm = 0;
unsigned long lastmillis = 0;
void setup(){
Serial.begin(9600);
attachInterrupt(0, rpm_fan, FALLING);//interrupt cero (0) is on pin two(2).
}
void loop(){
if (millis() - lastmillis == 1000){ /*Uptade every one second, this will be equal to reading frecuency (Hz).*/
detachInterrupt(0); //Disable interrupt when calculating
rpm = rpmcount * 60; /* Convert frecuency to RPM, note: this works for one interruption per full rotation. For two interrups per full rotation use rpmcount * 30.*/
Serial.print("RPM =\t"); //print the word "RPM" and tab.
Serial.print(rpm); // print the rpm value.
Serial.print("\t Hz=\t"); //print the word "Hz".
Serial.println(rpmcount); /*print revolutions per second or Hz. And print new line or enter.*/
rpmcount = 0; // Restart the RPM counter
lastmillis = millis(); // Uptade lasmillis
attachInterrupt(0, rpm_fan, FALLING); //enable interrupt
}
}
void rpm_fan(){ /* this code will be executed every time the interrupt 0 (pin2) gets low.*/
rpmcount++;
}
**********
Good morning,
Attached is a sketch that I personally like the feel of.
It compiles, so I am presuming that it does work properly.
However what I really like about it is the thought behind the sketch.
It has an interrupt attached, it can measure RPM, & it demonstrates how to update information every second with a hertz plotter too.
Hope that is of assistance
DafClaud.