Determining time elapsed in between two successive pulses of a signal

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Senal Perera
Senal Perera on 26 Mar 2021
Commented: Pat Gipper on 29 Mar 2021
I have a voltage signal from a rotary encoder which gives 1 pulse (4.5v) per revolution. I need to calculate the time elapsed between two successive peaks to get the speed of rotation. Can someone guide me please. My code is attached below. Thanks in advance.
a = arduino;
for i=1:inf
tic;
encoder_signal(i)= readVoltage(a, 'A2');
figure(1);
plot(encoder_signal);
ylabel('Encoder signal');
hold on;
pause(0.001);
if encoder_signal == 4.5;
x(i) = toc;
Engine_RPM (i) = (1/x)*60 ;
end
end
  1 Comment
Pat Gipper
Pat Gipper on 26 Mar 2021
How likely is it that the voltage is going to be exactly 4.5 Volts? I would think that you should trigger on the value exceeding a good threshold value (e.g. encoder_signal > 4).

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Accepted Answer

Pat Gipper
Pat Gipper on 27 Mar 2021
I updated your code a bit and fed in an artificial signal. It works but has a slight error due to loop delays running on my computer. You may need to adjust the threshold from 4.5 V depending on your actual encoder signal. If there is a lot of noise then the edge trigger would need hysteresis added to prevent double triggering.

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