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ADC interface — Parallax Forums

ADC interface

ArchiverArchiver Posts: 46,084
edited 2003-05-26 23:36 in General Discussion
I'd like to interface a total of 4 11-channel ADC's from TI to my BS2p
serially, but in order to conserve I/O space on the micon i was wondering if
i could simply run all four ADC's I/O clock pins to a single pin on the
micon. Since i will only be using one ADC at once, couldn't i also tie all
the DATA IN pins to a single pin on the micon and likewise with the DATA
OUT? If i do this, do i have to provide any buffering on the individual
ADC's?
Thanks,
Christian

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Comments

  • ArchiverArchiver Posts: 46,084
    edited 2003-05-26 01:15
    In a message dated 5/25/2003 6:53:18 PM Eastern Daylight Time,
    cwentz86@h... writes:

    > I'd like to interface a total of 4 11-channel ADC's from TI to my BS2p
    > serially, but in order to conserve I/O space on the micon i was wondering if
    >
    > i could simply run all four ADC's I/O clock pins to a single pin on the
    > micon. Since i will only be using one ADC at once, couldn't i also tie all
    > the DATA IN pins to a single pin on the micon and likewise with the DATA
    > OUT? If i do this, do i have to provide any buffering on the individual
    > ADC's?
    >

    Are you using TLC2543's?

    Sid


    [noparse][[/noparse]Non-text portions of this message have been removed]
  • ArchiverArchiver Posts: 46,084
    edited 2003-05-26 03:49
    i'm using TLV2553's


    >From: Newzed@a...
    >Reply-To: basicstamps@yahoogroups.com
    >To: basicstamps@yahoogroups.com
    >Subject: Re: [noparse][[/noparse]basicstamps] ADC interface
    >Date: Sun, 25 May 2003 20:15:22 EDT
    >
    >In a message dated 5/25/2003 6:53:18 PM Eastern Daylight Time,
    >cwentz86@h... writes:
    >
    > > I'd like to interface a total of 4 11-channel ADC's from TI to my BS2p
    > > serially, but in order to conserve I/O space on the micon i was
    >wondering if
    > >
    > > i could simply run all four ADC's I/O clock pins to a single pin on the
    > > micon. Since i will only be using one ADC at once, couldn't i also tie
    >all
    > > the DATA IN pins to a single pin on the micon and likewise with the DATA
    > > OUT? If i do this, do i have to provide any buffering on the individual
    > > ADC's?
    > >
    >
    >Are you using TLC2543's?
    >
    >Sid
    >
    >
    >[noparse][[/noparse]Non-text portions of this message have been removed]
    >
    >
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  • ArchiverArchiver Posts: 46,084
    edited 2003-05-26 13:32
    In a message dated 5/25/2003 10:50:46 PM Eastern Daylight Time,
    cwentz86@h... writes:

    > i'm using TLV2553's
    >

    I have done what you want to do with shift registers but not ADCs. My guess
    is that the best approach would be to keep the clock lines separate and
    parallel all the others. I would also put a 1K resistor in each clock, datain,
    dataout and chip select line just in case.

    Sid


    [noparse][[/noparse]Non-text portions of this message have been removed]
  • ArchiverArchiver Posts: 46,084
    edited 2003-05-26 14:52
    Usually it works like this:

    Connect ADC inputs and outputs to a single IO line (each output
    through a resistor, e.g. 1k). Connect all ADC clocks to a common
    clock line. Connect each ADC Chip Select (CS) individually to the
    one of the other IO pins of the stamp. Disable all CS at startup
    and enable one to access a specific ADC.
    My be the Chip Select line is named differently on your ADC but
    it serves the same purpose

    Regards
    Adrian
  • ArchiverArchiver Posts: 46,084
    edited 2003-05-26 23:36
    Building off what Adrian said:

    One other suggestion: if you really want to conserve I/O lines, you
    could control those four -CS lines using just three data lines with
    the 74259 addressable latch (a demux. with a latchable data bit).
    Run those three lines to A (aka - A0), B (A1), and D (Data), ground
    C (A2)*, tie the four -CS lines to Q0 - Q3. That'll give you four
    usable outputs which you can address using A,B and then
    enable/disable with the latched data bit.

    http://www.fairchildsemi.com/ds/DM/DM74LS259.pdf

    *Note: you could control 8 A/D's with the addition of just one more
    address line!


    --- In basicstamps@yahoogroups.com, "Christian Wentz"
    <cwentz86@h...> wrote:
    > I'd like to interface a total of 4 11-channel ADC's from TI to my
    BS2p
    > serially, but in order to conserve I/O space on the micon i was
    wondering if
    > i could simply run all four ADC's I/O clock pins to a single pin
    on the
    > micon. Since i will only be using one ADC at once, couldn't i
    also tie all
    > the DATA IN pins to a single pin on the micon and likewise with
    the DATA
    > OUT? If i do this, do i have to provide any buffering on the
    individual
    > ADC's?
    > Thanks,
    > Christian
    >
    > _________________________________________________________________
    > MSN 8 with e-mail virus protection service: 2 months FREE*
    > http://join.msn.com/?page=features/virus
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