I tried to create a tachometer for my motorcycle using an Arduino Uno.
I am trying to measure the voltage of the ignition coil (stepped down to not destroy the Arduino).
I am trying to determine the time between two explosions (one ignition coil high voltage).
I tried to use the pulseIn
command in the following way:
unsigned pin=8;
float t;
unsigned long rpm;
void setup() {
Serial.begin(9600);
pinMode(pin,INPUT);
}
void loop() {
rpm=pulseIn(pin,LOW);
Serial.println(rpm/60);
}
The problem with it is that it won't display stable values. It will go all crazy. With an open circuit it still displays random values.