Is discrete input signal still raw after it is debounced ?

Started by learn 7 years ago4 replieslatest reply 7 years ago363 views
Consider a typical Automotive Embedded  Software System.  

A discrete input signal is 0 or 1.  An example of discrete input is ignition ON or OFF.

After discrete input signal is debounced or a state change is latched, is discrete input signal still raw value?

Second question:   Should Electronic Control Unit (ECU) low level software debounce discrete inputs or just read the real time state of discrete input?  Are there any exceptions meaning some discrete inputs should be debounced, whereas others don't need to be debounced?
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Reply by jkvasanMay 8, 2017

Hi learn,

Debouncing is kind of filtering the glitches and sensing whether an intentional level change has happened or not. The raw signal cannot be the same as the debounced output. If you need both the signals' data to be stored, you may have to use a fast ADC input and sample the raw value and plot.

Decision making on when to debounce :

It depends on the signal source. For example , if your signal comes from a rocker switch or a relay contact, you need to debounce. A digital signal coming from a RS232 level converter may not need debouncing. An optical slot sensor sensing rpm may not have such bouncing outputs and you can directly process its output.

Suggestion : Pls post all your queries , however trivial they may be. Life is always a journey in the path of learning. There may be thousand simple things that we may not know but that does not make us any less.

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Reply by Tim WescottMay 8, 2017

My raw is your cooked.  Or visa-versa.  As you go up the layers of control, one layer's "processed" will be some other layer's "raw".  It's all about the angle you're looking from.

Generally, use "raw" or "processed" in a way that will lead to the best understanding in the reader.  All of the rest is just arguing over semantics.

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Reply by jt_eatonMay 8, 2017

Why don't you post your entire homework assignment and let us know where we should send after we fill it out?

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Reply by learnMay 8, 2017

This is not homework.  I'm not in school.