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Dot matrix display

Discussion in 'Electronic Basics' started by Roger Dewhurst, Mar 18, 2007.

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  1. I have been given a number of 7x5 dot matrix display segments. There are 7
    pins at the top and 7 at the bottom. The ID on the segment is:

    927 TAIWAN P

    Can someone be kind enough to explain the pin-out for me.

  2. BobG

    BobG Guest

    Try an ohmmeter on diode test setting both ways.... could be common
    anode or common cathode
  3. Chris

    Chris Guest

    Hi, Roger. Can't find the part -- I'd guess you might have to get out
    your DMM and use the diode tester.

    Here's a standard pinout that might help:

    ood luck
  4. Thanks. This looks like an identical device!

  5. I have printed out the document but how do I work out what the pins do.

    I can see that there are 8 anode pins and 6 cathode pins but that is about
    as far as I get.

  6. Randy Day

    Randy Day Guest

    Roger Dewhurst wrote:

    Connect 3 to 5 volts (through a current-limiting
    resistor), negative to one cathode, positive to
    each anode in turn; each time a different spot
    should come on. Move neg. to the next cathode,
    then pos. to each anode again - different spots
    come on.

    |-----/\/\/\--- cathode
    --- 3-5VDC
    |-------------- anode

    Choose the resistor value to limit current to
    25mA. As the small schematic in the doc with all
    the diodes shows, they're arranged in a row-col
  7. Chris

    Chris Guest

    Hi, Roger. Driving the displays you have might not be the easiest
    thing for a newbie. They work on the time multiplexing principle. If
    you apply 7 bits of data to the anode pins, and then activate one of
    the cathode pins, one row of the diplay will light. By using a
    computer or microcontroller amd appropriate high current latching
    drivers, you can scroll across the rows at a fast rate (say, 1000
    times a second or so), and due to persistence of vision it will appear
    that all the rows are on at once. A typical microcontroller can
    easily handle this and also take care of other things such as
    maintaining a communications link and taking care of other business.

    But unless you've got that microcontroller, it is going to be really
    difficult to get a whole lot of use out of your display.

    Good luck
  8. Thanks. I just wanted to use them to display a time in milliseconds between
    two events. Since I got a bunch of these 7x5 LED matrix devices I thought
    that I might try and use them. Obviously there are easier ways.

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