Hardware filter for Parallel Input/Output

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Hardware filter for Parallel Input/Output

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Brax02
Contributor III

Hello,

 

With a MC9S08 I configure the parallel port in input.

 

My questions is how is filtered this input  by the hardware? Against glitch etc ?

 

Are several aquisitions done  before to transmit a value to the software ?

 

When is the value of the port refresh ? Every BUSCLK ?

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Monica
Senior Contributor III

Hello Brax02,

was this suggestion helpful?

Please keep us posted, we'd like to know :smileywink:

Best,

Monica.

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Derrick
NXP Employee
NXP Employee

Hello,

Regular input port pins are synchronized by the bus clock, but they are not "filtered".  On regular port pins, input signal transitions that are faster than 1.5 bus clocks will normally be recognized.  So the input port data is effectively updated upon every bus clock cycle.

You will need to use application software techniques if you need to filter, deglitch or debounce input signals.

Best Regards,

Derrick


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