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MAX7219 LED Driver — Parallax Forums

MAX7219 LED Driver

ArchiverArchiver Posts: 46,084
edited 2000-04-18 02:42 in General Discussion
I am trying to use the MAX7219 along with a keypad to output the
numbers selected by the user. The user selects for example, 400 on
the key pay, I would like to display each number as it is entered,
display the total number entered, then when the program runs, begin a
count down from 400 and stops on 0. I have very limited knowledge on
the Stamp, and any ideals, hints or directions would greatly help me
out.

thanks,
John

Comments

  • ArchiverArchiver Posts: 46,084
    edited 2000-04-18 02:42
    In case you don't have your 7219 going yet here is a pointer. USE THE 10uF
    CAP AS IS THE SCOTT EDWARDS STAMP APP. IT IS NOT OPTIONAL. SAVE YOURSELF 3
    HOURS OF HASSEL TRYING TO FIGURE THAT OUT. I'm not trying to be rude but it
    is REALLY important that the cap is there and that it is physically within
    about 1"(of wire) of the 7219. It took me 3 hours to figure that out, very
    frustrating. Also to make entering the numbers look better you may have to
    have the digits "shift" their current value one digit to the left. This is
    kinda a tricky, but is certainly do able.
    Here is what I mean, say you wanted to enter the number 178. the digits
    could appear as follows if you don't "shift" the digits. B=blank

    1BBBBBBB
    17BBBBBB
    178BBBBB

    if you do your shifting right it'll look like this.

    BBBBBBB1
    BBBBBB17
    BBBBB178

    Let me know if you need any help. I have had a great deal of experience
    with the MAX7219. BTW, if you want a challenge write code that scrolls a
    quantity on the digits.


    >From: tripwire27@h...
    >Reply-To: basicstamps@egroups.com
    >To: basicstamps@egroups.com
    >Subject: [noparse][[/noparse]basicstamps] MAX7219 LED Driver
    >Date: Mon, 17 Apr 2000 23:26:36 -0000
    >
    >I am trying to use the MAX7219 along with a keypad to output the
    >numbers selected by the user. The user selects for example, 400 on
    >the key pay, I would like to display each number as it is entered,
    >display the total number entered, then when the program runs, begin a
    >count down from 400 and stops on 0. I have very limited knowledge on
    >the Stamp, and any ideals, hints or directions would greatly help me
    >out.
    >
    >thanks,
    >John
    >
    >
    >
    >

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