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Minimum amplitude of pulse for microcontroller

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arunbhaskar

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Hello guys.

I need to know what is the minimum value of amplitude of a pulse that will be counted when I configure the microcontroller to work as an external counter. I need the details for AT89S51.
 

Check the datasheet for the absolute ratings. Should be 3.0V.
 

It is the min value for a high signal as stated in the Data Sheet. Another value might be of interest, the minimal duration of a pulse to make sure it was counted. It is several clock cycles, don't know how many for this specific device though.

hth, Bob
 

.. should be 3.0V ..
Click to expand...

The V[cc] for AT89S51 can vary from 4V to 5.5V, so the V[IH] somehow follows the V[cc] ..
The formula says V[IH]min ≥{0.2*V[cc] + 0.9V}, and what that means at, say, V[cc]=5V it’s easy to guess ..

Rgds,
IanP
:|
 

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