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07/04/06 09:12
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 		 #119606 - Debouncing with an 8051 of 16 I/O pins
Hello guys.

As some of you know, I am working on DAQ system that reads things from 64 input relays.
I searched for debouncing techniques here for quite some time. And I think that the easiest (of the inexpensive) technique is writing a debouncing program in a separate 8051 and make it into just a debouncer chip. It is more economic than the commercially available debounces (like max6818, which is not even readily available here in India) and does not take away processing speed from the main chip. I need to interface 8x8 input lines with one input port of an 89C51. So I want to debounce a set of 8 lines each using one additional “Debouncer-Microcontroller” and send each set into a separate latch (74ls373) so I can selectively receive inputs only from one latch at a time. But being the uninformed enthusiast that I am, I am unable to find an 8051 based chip that has 16 I/O lines in 2 ports. I found that an AT89C2051 has on 15 programmable I/O lines. So I have a few questions:

1. Is there an inexpensive 8051 based Microcontroller with 16 I\O lines (i.e. 2 ports) to serve my purpose of a “Debouncer-Microcontroller”?

2. Is it necessary to use a latch? Or is there a technique to forego the latch?

Also any other ideas of solving my problem are welcome.

List of 34 messages in thread
TopicAuthorDate
Debouncing with an 8051 of 16 I/O pins            01/01/70 00:00      
   You don't need these slave micros            01/01/70 00:00      
      yes, but some more questions            01/01/70 00:00      
         Not scary at all...            01/01/70 00:00      
            In that case.....            01/01/70 00:00      
            here is the schematic            01/01/70 00:00      
               I would try shift registers            01/01/70 00:00      
               just a note            01/01/70 00:00      
                  The joke is:            01/01/70 00:00      
                     the reality is            01/01/70 00:00      
                     Re: The joke is            01/01/70 00:00      
      correct, but            01/01/70 00:00      
         I was assuming...            01/01/70 00:00      
   Bounce time of your relays?            01/01/70 00:00      
      Not very clearly            01/01/70 00:00      
         Bravo!            01/01/70 00:00      
   The original question            01/01/70 00:00      
      What's wrong with the shift register sol            01/01/70 00:00      
      HUH?            01/01/70 00:00      
         I am sorry            01/01/70 00:00      
            that was not the issue            01/01/70 00:00      
   why oh why oh why oh why            01/01/70 00:00      
      because it cost nothing            01/01/70 00:00      
         yeah right            01/01/70 00:00      
            yes, they do            01/01/70 00:00      
            Design is a state function            01/01/70 00:00      
               All the more using shift registers!            01/01/70 00:00      
                  I think your solution is better            01/01/70 00:00      
                     I guessed so...            01/01/70 00:00      
                  hidden part            01/01/70 00:00      
                     I can see a 'lucky sample' of a shift re            01/01/70 00:00      
                     True, but...            01/01/70 00:00      
   jezwolds hardware switch debouncer            01/01/70 00:00      
   The facts about costs of Debouner chips            01/01/70 00:00      

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