[SOLVED] positive zero crossing

[zouzanda]

hello please i need a help from anyone.my problem is that i need to detect with a pic the zero crossing in yellow not in red.how can i do that??
thank you in advance

 

[str4code]

You can use your signal as clock pulse to the PIC micro controller as a counter either on rising (Yellow) or falling (Red) edge of the clock pulses.
https://embedded-lab.com/blog/lab-7-timers-and-counters-part-1/

 

[Okada]

Configure INT0 to detect rising edge. In interrupt service routine write code for what you want to do when INT0IF bit is set.

Do you want ZCD circuit or code or both ?

 

[KlausST]

Hi,

Zero cross is at both falling and rising sine signal.
If you use a comparator, then it's output is also a digital signal with falling and rising edge.

As suggested before you can trigger on the rising (or falling) edge only.

An external comparator can have the benefit, that it can handle negative input voltages.

Klaus

 

[ftsolutions]

Also with a comparator circuit, you can add in some hysteresis so that you get good clean edges/pulse output on what could be slowly changing input signal. This helps to avoid missing or multiple counting the zero cross events.

 

[zouzanda]

ok thank you guys .the problem is that i need to do all that using hardware not software my micro need to read only if it crossed the zero or not and i cannot use interrupt in that case.
anyone has an idea?

 

[KlausST]

Hi,

Is it solved now, or not?

If not, then please draw a diagram with input signal and desired output signal.

Klaus

 

[Okada]

Yes, it can be done with pooling but only if your micro hasen't have to do any other thing.