Groups > sci.electronics.design > #457999

Re: Binary counter - please check my work

From	rickman <gnuarm@gmail.com>
Newsgroups	sci.electronics.design
Subject	Re: Binary counter - please check my work
Date	2017-04-29 14:54 -0400
Organization	A noiseless patient Spider
Message-ID	<oe2nb5$cc8$1@dont-email.me> (permalink)
References	(2 earlier) <l1TMA.48233$uf1.15437@fx40.iad> <oe0vro$ogs$1@dont-email.me> <YRUMA.1140$aC3.868@fx02.iad> <oe2c8b$39u$1@dont-email.me> <ww3NA.59864$0%5.55503@fx38.iad>

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On 4/29/2017 12:51 PM, bitrex wrote:
> On 04/29/2017 11:45 AM, Don Y wrote:
>> On 4/28/2017 9:43 PM, bitrex wrote:
>>> On 04/28/2017 11:07 PM, Don Y wrote:
>>>> On 4/28/2017 7:39 PM, bitrex wrote:
>>>>> On 04/28/2017 07:20 PM, Don Y wrote:
>>>>>> On 4/28/2017 4:14 PM, bitrex wrote:
>>>>>>> I'd like to have a 74HC163 4-bit counter count the following
>>>>>>> sequence:
>>>>>>>
>>>>>>> 1000
>>>>>>> 1001
>>>>>>> 1010
>>>>>>> 1011
>>>>>>> 0100
>>>>>>> 0101
>>>>>>> 0110
>>>>>>> 0111
>>>>>>>
>>>>>>> So A, B preset inputs grounded, C, D preset fed back from the
>>>>>>> outputs
>>>>>>> C, D
>>>>>>> swapped, synchronous preset enable pin (active low) NANDed from A
>>>>>>> and B?
>>>>>>
>>>>>> Why not just use the three LSb's of the counter "as is"and
>>>>>> inverting the
>>>>>> most
>>>>>> significant of those (with your NAND gate) to form the MSb (of four)?
>>>>>
>>>>> Ah, indeed, indeed.
>>>>>
>>>>> DUH.
>>>>>
>>>>> This is why I ask...;-)
>>>>
>>>> There are no "steady state" consequences of this.  However, the
>>>> temporal behavior of the "4th bit" will vary near the clock edge
>>>> as it will be more closely synchronized with the other three bits
>>>> in the case where the state is set-up *before* the clock edge
>>>> vs. derived from the TRANSITIONED third bit AFTER the clock edge.
>>>
>>> "El Cheapo" 2 switch sample and hold is my ideal, but I don't know
>>> that it's
>>> possible:
>>>
>>> <https://www.dropbox.com/s/t1lkycctbqojpt5/20170429_003617.jpg?dl=0>
>>
>> I don't see a second switch...
>>
>> Presumably, you're using some combinatorial logic to "decode" the
>> "current state" (or "current selection?") from the counter to
>> control/sequence the switches.  See my notes in other post re: the
>> hazzard this presents (esp as you don't want to be "jittering"
>> the switch(es) needlessly).
>
> The idea I was thinking about was to somehow use the diodes _themselves_
> as the switches. Kills two birds with one stone maybe - they act as the
> combinatorial logic (diode logic) and also the switch.
>
> I'd like a sample & hold that has better performance (than just running
> 8 4051 outputs to the non-inverting input of a JFET op-amp and hanging a
> cap off it) but don't think I really have the budget for 8 SPDT analogs
> switches as Win suggested. Trying to get creative here, mostly failing. :-)

why do they need to be SPDT?  Won't a SPST do the job?  You get four on 
a chip so 8 would only be two chips.

-- 

Rick C

Thread

Binary counter - please check my work bitrex <bitrex@de.lete.earthlink.net> - 2017-04-28 19:14 -0400
  Re: Binary counter - please check my work Don Y <blockedofcourse@foo.invalid> - 2017-04-28 16:20 -0700
    Re: Binary counter - please check my work rickman <gnuarm@gmail.com> - 2017-04-28 19:31 -0400
    Re: Binary counter - please check my work bitrex <bitrex@de.lete.earthlink.net> - 2017-04-28 22:39 -0400
      Re: Binary counter - please check my work Don Y <blockedofcourse@foo.invalid> - 2017-04-28 20:07 -0700
        Re: Binary counter - please check my work bitrex <bitrex@de.lete.earthlink.net> - 2017-04-29 00:27 -0400
          Re: Binary counter - please check my work Don Y <blockedofcourse@foo.invalid> - 2017-04-28 22:44 -0700
            Re: Binary counter - please check my work Don Y <blockedofcourse@foo.invalid> - 2017-04-28 22:46 -0700
            Re: Binary counter - please check my work rickman <gnuarm@gmail.com> - 2017-04-29 10:29 -0400
              Re: Binary counter - please check my work bitrex <bitrex@de.lete.earthlink.net> - 2017-04-29 11:07 -0400
              Re: Binary counter - please check my work bill.sloman@ieee.org - 2017-04-29 20:34 -0700
                Re: Binary counter - please check my work rickman <gnuarm@gmail.com> - 2017-04-29 23:43 -0400
                Re: Binary counter - please check my work bill.sloman@ieee.org - 2017-04-29 21:53 -0700
                Re: Binary counter - please check my work rickman <gnuarm@gmail.com> - 2017-04-30 01:42 -0400
                Re: Binary counter - please check my work bill.sloman@ieee.org - 2017-04-29 23:28 -0700
                Re: Binary counter - please check my work rickman <gnuarm@gmail.com> - 2017-04-30 20:10 -0400
                Re: Binary counter - please check my work bitrex <bitrex@de.lete.earthlink.net> - 2017-04-30 20:26 -0400
                Re: Binary counter - please check my work rickman <gnuarm@gmail.com> - 2017-04-30 21:07 -0400
                Re: Binary counter - please check my work rickman <gnuarm@gmail.com> - 2017-04-30 21:20 -0400
                Re: Binary counter - please check my work bill.sloman@ieee.org - 2017-04-30 18:52 -0700
                Re: Binary counter - please check my work rickman <gnuarm@gmail.com> - 2017-05-01 08:43 -0400
                Re: Binary counter - please check my work krw@notreal.com - 2017-05-01 13:33 -0400
                Re: Binary counter - please check my work bill.sloman@ieee.org - 2017-05-01 23:02 -0700
                Re: Binary counter - please check my work Jasen Betts <jasen@xnet.co.nz> - 2017-05-02 11:42 +0000
                Re: Binary counter - please check my work bill.sloman@ieee.org - 2017-05-02 06:10 -0700
                Re: Binary counter - please check my work upsidedown@downunder.com - 2017-05-03 03:26 +0300
                Re: Binary counter - please check my work pcdhobbs@gmail.com - 2017-05-02 18:41 -0700
                Re: Binary counter - please check my work bill.sloman@ieee.org - 2017-05-02 19:39 -0700
                Re: Binary counter - please check my work rickman <gnuarm@gmail.com> - 2017-05-02 11:30 -0400
          Re: Binary counter - please check my work Jasen Betts <jasen@xnet.co.nz> - 2017-04-29 20:25 +0000
            Re: Binary counter - please check my work rickman <gnuarm@gmail.com> - 2017-04-29 23:15 -0400
              Re: Binary counter - please check my work upsidedown@downunder.com - 2017-05-01 11:12 +0300
        Re: Binary counter - please check my work bitrex <bitrex@de.lete.earthlink.net> - 2017-04-29 00:43 -0400
          Re: Binary counter - please check my work Winfield Hill <hill@rowland.harvard.edu> - 2017-04-29 05:31 -0700
            Re: Binary counter - please check my work bitrex <bitrex@de.lete.earthlink.net> - 2017-04-29 09:48 -0400
          Re: Binary counter - please check my work Don Y <blockedofcourse@foo.invalid> - 2017-04-29 08:45 -0700
            Re: Binary counter - please check my work bitrex <bitrex@de.lete.earthlink.net> - 2017-04-29 12:51 -0400
              Re: Binary counter - please check my work rickman <gnuarm@gmail.com> - 2017-04-29 14:54 -0400
              Re: Binary counter - please check my work Don Y <blockedofcourse@foo.invalid> - 2017-04-29 12:34 -0700
                Re: Binary counter - please check my work bitrex <bitrex@de.lete.earthlink.net> - 2017-04-29 15:51 -0400
                Re: Binary counter - please check my work Don Y <blockedofcourse@foo.invalid> - 2017-04-29 21:37 -0700
            Re: Binary counter - please check my work Jasen Betts <jasen@xnet.co.nz> - 2017-04-29 20:49 +0000
              Re: Binary counter - please check my work Don Y <blockedofcourse@foo.invalid> - 2017-04-29 14:08 -0700
              Re: Binary counter - please check my work bitrex <bitrex@de.lete.earthlink.net> - 2017-04-29 17:31 -0400
                Re: Binary counter - please check my work Jasen Betts <jasen@xnet.co.nz> - 2017-04-30 00:51 +0000
                Re: Binary counter - please check my work bitrex <bitrex@de.lete.earthlink.net> - 2017-04-29 21:42 -0400
          Re: Binary counter - please check my work bloggs.fredbloggs.fred@gmail.com - 2017-04-29 12:17 -0700
            Re: Binary counter - please check my work bitrex <bitrex@de.lete.earthlink.net> - 2017-04-29 15:36 -0400
              Re: Binary counter - please check my work bloggs.fredbloggs.fred@gmail.com - 2017-04-30 08:00 -0700
                Re: Binary counter - please check my work bitrex <bitrex@de.lete.earthlink.net> - 2017-04-30 11:13 -0400
                Re: Binary counter - please check my work bitrex <bitrex@de.lete.earthlink.net> - 2017-04-30 11:24 -0400
                Re: Binary counter - please check my work bloggs.fredbloggs.fred@gmail.com - 2017-04-30 08:30 -0700
                Re: Binary counter - please check my work bitrex <bitrex@de.lete.earthlink.net> - 2017-04-30 16:06 -0400
  Re: Binary counter - please check my work Jasen Betts <jasen@xnet.co.nz> - 2017-04-29 00:04 +0000
  Re: Binary counter - please check my work bill.sloman@ieee.org - 2017-04-28 21:14 -0700
  Re: Binary counter - please check my work stratus46 <stratus46@yahoo.com> - 2017-05-01 01:51 -0700
    Re: Binary counter - please check my work stratus46 <stratus46@yahoo.com> - 2017-05-01 01:56 -0700
      Re: Binary counter - please check my work bitrex <bitrex@de.lete.earthlink.net> - 2017-05-01 13:36 -0400

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