topic Hardware filter for Parallel Input/Output in 8-bit Microcontrollers

Hardware filter for Parallel Input/Output

Brax02 — Thu, 05 Sep 2013 09:38:18 GMT

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 ?

Re: Hardware filter for Parallel Input/Output

Derrick — Thu, 05 Sep 2013 14:19:23 GMT

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

Re: Hardware filter for Parallel Input/Output

Monica — Fri, 13 Sep 2013 21:41:18 GMT

Hello Brax02,

was this suggestion helpful?

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

Best,

Monica.