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multiplexing chips for stamp2? — Parallax Forums

multiplexing chips for stamp2?

ArchiverArchiver Posts: 46,084
edited 2004-04-17 20:56 in General Discussion
Does anyone know of a multiplexer for a Stamp2. I vaguely remember
something about an I2c multiplexer somewhere. Basically I need to
be able to control 100 relays in a 10X10 grid, being able to turn
each one off and on individually. I need isolated control for each
relay, so shift registers won't work. Please help. I teach an
electronics class and my students are frequently asking for similar
needs.

Comments

  • ArchiverArchiver Posts: 46,084
    edited 2004-04-17 18:24
    > Does anyone know of a multiplexer for a Stamp2. I vaguely remember
    > something about an I2c multiplexer somewhere. Basically I need to
    > be able to control 100 relays in a 10X10 grid, being able to turn
    > each one off and on individually. I need isolated control for each
    > relay, so shift registers won't work. Please help. I teach an
    > electronics class and my students are frequently asking for similar
    > needs.

    What you're looking for is the "Philips PCF8574 Remote I/O Expander". You
    can put up to eight of these on two BS2 pins for 64 bits of I/O. Use five
    more on two other BS2 pins for an additional 40 bits of I/O for a total of
    104. Each of these could be used to control the relay drivers.

    --
    Enjoy,
    George Warner,
    Schizophrenic Optimization Scientists
    Apple Developer Technical Support (DTS)
  • ArchiverArchiver Posts: 46,084
    edited 2004-04-17 20:56
    If you're going to to that route, use the MCP23016. It has 16 IO pins
    per device, and each pin can sink/source 25 mA so it is much better for
    driving LEDs.

    -- Jon Williams
    -- Applications Engineer, Parallax
    -- Dallas Office


    Original Message
    From: George Warner [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=QTTDNHLPq3ZEakxvbgVeLcjTh_uok2opr3xO9q0VZAeVJhLzmb0YjBhilzsXHAd1CWwZEl8Kcx44]geowar@a...[/url
    Sent: Saturday, April 17, 2004 12:24 PM
    To: basicstamps@yahoogroups.com
    Cc: Gary Goddard
    Subject: [noparse][[/noparse]basicstamps] re: multiplexing chips for stamp2?


    > Does anyone know of a multiplexer for a Stamp2. I vaguely remember
    > something about an I2c multiplexer somewhere. Basically I need to be
    > able to control 100 relays in a 10X10 grid, being able to turn each
    > one off and on individually. I need isolated control for each relay,
    > so shift registers won't work. Please help. I teach an electronics
    > class and my students are frequently asking for similar needs.

    What you're looking for is the "Philips PCF8574 Remote I/O Expander".
    You can put up to eight of these on two BS2 pins for 64 bits of I/O. Use
    five more on two other BS2 pins for an additional 40 bits of I/O for a
    total of 104. Each of these could be used to control the relay drivers.

    --
    Enjoy,
    George Warner,
    Schizophrenic Optimization Scientists
    Apple Developer Technical Support (DTS)
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