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PICList Thread
'LED Display driving'
1998\07\16@113528 by ali

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Hi,

In a PIC based project I need to drive 3 groups of 8 digits 7+1
segment (including decimal point) LED displays.

Any suggession will be appreciated..

Thanks...

1998\07\16@120653 by Ricardo Seixas

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Ali,

I can see two paths:
1) You can multiplex the 3 displays (11 pins used). See AN557 for an example.
2) Use 3 shift-register in cascade (i.e. 74595), in this case you use only
3 pins to control
all 24 outputs.

Ricardo Seixas


{Quote hidden}

1998\07\16@132554 by andre

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> A few days ago I posted swtester.asm file that

uses two led display. you can modify mycode very easy. just add 3 Th. register
and
shift subroutine. for first digit REGA for
second digit REGB. wiring  I did very simple

RB0 - DT
RB1 - A
RB2 - B
RB3 - C
RB4 - D
RB5 - E
RB6 - F
RB7 - G

RA0 - to select first digit
RA1 - to select second digit

I used TMR0 for brightness.

Andre Abelian

{Quote hidden}

1998\07\16@132957 by Steve Lawther

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    Ali,

    So its 24 off 7 seg + d.p displays?

    Seems a job for 3 off MAX7129 (I think that's the number) three
wire
    bus to 8 x 7 seg + d.p displays driver controller or for 2 off
Texas
    Inst. TLC5920 16x8bit LED driver controller.

    As for availability - both devices are in production, but I
remember a
    while back people has problems getting the maxim device quickly,
and
    I've only learnt about the TI device this week. The TI data says it

    has been in production from nov '97 at least.

    Hope it helps,

               Steve Lawther



______________________________ Reply Separator
_________________________________
Subject: LED Display driving
Author:  Ali Haydar GOKTOGAN [SMTP:spam_OUTaliTakeThisOuTspamDYNAMITE.COM.AU]  at UKExchange
Date:    16/07/98 15:46


Hi,

In a PIC based project I need to drive 3 groups of 8 digits 7+1
segment (including decimal point) LED displays.

Any suggession will be appreciated..

Thanks...

1998\07\16@155937 by PIC development

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Have you used the '7219. I read the datasheet and thought Yes! this is
just what I want to drive one of those little 8 digit "bubble" display
that the older members of this list may remember in LED calculators.
(pass my walking stick, it's over by my pensioners bus pass).

I got it to work, eventually but it was difficult. In the end I had
to run it at 4V - any higher and the internal oscillator would stop
and freeze the display. In a moment of doubt, I actually thought there
was a bug in my code :-)

Got it to work, and it now has pride of place in a microsecond resolution
stopwatch using a 16c84. Code available on request - but I'm not very
proud of it

Pete

..............................................................................
. Never trust a man who, when left alone in ....... Pete Lynch               .
. a room with a tea cosy, doesn't try it on ....... Marlow, England          .
..........Billy Connolly. ......................... .....picKILLspamspam@spam@beowulf.demon.co.uk ..


On Thu, 16 Jul 1998, Steve Lawther wrote:

{Quote hidden}

1998\07\16@172234 by Michael S. Hagberg

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MAX7219. the only trouble i had was getting it to initialize on startup. i
resolved the problem by initializing the display inside my first display
loop. (when the device was powered on i display 'AAA' for two seconds)

michael


-----Original Message-----
From: Ali Haydar GOKTOGAN <.....aliKILLspamspam.....dynamite.com.au>
To: EraseMEPICLISTspam_OUTspamTakeThisOuTMITVMA.MIT.EDU <PICLISTspamspam_OUTMITVMA.MIT.EDU>
Date: Thursday, July 16, 1998 10:45 AM
Subject: LED Display driving


Hi,

In a PIC based project I need to drive 3 groups of 8 digits 7+1
segment (including decimal point) LED displays.

Any suggession will be appreciated..

Thanks...

1998\07\17@024245 by Dr. Imre Bartfai

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Hi,
I use daisy-chained 74164's, each for very digit. I need only 2 wire for
one display. The Pic Basic Pro does it fine with SHIFTOUT command, but it
is easy to write it in assembly, too. I think for your three groups you
can connect all the DATA lines, only the CLOCK lines should be separate.
If you want nice result, you should turn the display OFF whilst updating
their content. And don't forget the correct CLEAR circuit.

I hope it helps you.

Imre


On Fri, 17 Jul 1998, Ali Haydar GOKTOGAN wrote:

{Quote hidden}

1998\07\17@142014 by Calvin

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If you want to use the '164, you will only need one line for CLK and another
one for DATA, tie all the clock inputs for every '164 together, and the last
output of every '164 to the data input of the next. If you do it fast
enough, you don't even need to shut off the displays while updating.

The way I do it is, with two '164s and four 7447s, and I only use two
microcontroller pins.

Calvin

{Original Message removed}

1998\07\17@163700 by rank A. Vorstenbosch

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Steve Lawther wrote:
>
> So its 24 off 7 seg + d.p displays?
>
> Seems a job for 3 off MAX7129 (I think that's the number) three wire
> bus to 8 x 7 seg + d.p displays driver controller or for 2 off Texas
> Inst. TLC5920 16x8bit LED driver controller.

Hmmm, looking it up in QuestLink and on the TI website didn't give any
results.  Do you have a pointer to a datasheet for this device?  Somewhere
on TI's website???

Thanks,
Frank
------------------------------------------------------------------------
Frank A. Vorstenbosch    <UCE_ACCEPT="NONE">    Mobile:  +44-976-430 569
Wimbledon, London SW19                          Home:   +44-181-544 1865
@spam@frankKILLspamspamfalstaff.demon.co.uk                      Office: +44-181-636 3391

1998\07\17@191912 by Michael S. Hagberg

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Maxim wouldn't like your reference to TI try this link

http://209.1.238.250/arpdf/1339.pdf

michael


{Original Message removed}

1998\07\20@044017 by Steve Lawther

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    Sorry Frank / All,

    You're right about it not being on the ti web site.

    Having looked at the paper copy again, although the front page says

    'production data' - not 'preliminary' and is dated nov 97, looking
on
    the back cover says:-

    Document code SODSE01 - copyright TI 5/98

    So I guess it's just released - But TI wants you to believe it's
    mature(?)

            Steve Lawther


______________________________ Reply Separator
_________________________________
Subject: Re: LED Display driving
Author:  Frank A. Vorstenbosch [SMTP:KILLspamfrankKILLspamspamFALSTAFF.DEMON.CO.UK]  at
UKExchange
Date:    17/07/98 21:26


Steve Lawther wrote:
>
> So its 24 off 7 seg + d.p displays? >
> Seems a job for 3 off MAX7129 (I think that's the number) three wire
> bus to 8 x 7 seg + d.p displays driver controller or for 2 off Texas
> Inst. TLC5920 16x8bit LED driver controller.

Hmmm, looking it up in QuestLink and on the TI website didn't give any
results.  Do you have a pointer to a datasheet for this device?
Somewhere
on TI's website???

Thanks,
Frank
------------------------------------------------------------------------

Frank A. Vorstenbosch    <UCE_ACCEPT="NONE">    Mobile:  +44-976-430 569

Wimbledon, London SW19                          Home:   +44-181-544 1865

RemoveMEfrankTakeThisOuTspamfalstaff.demon.co.uk                      Office: +44-181-636 3391

1998\07\21@043642 by Jose Antonio Gracia

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part 0 542 bytes content-type:text/x-vcard; charset=us-ascii; name="vcard.vcf"--
Un saludo a todos
               Jose Antonio Gracia

spamBeGonejgranespamBeGonespamcolon.net
http://www.geocities.com/SiliconValley/Pines/7097


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1998\07\21@052253 by Frank A. Vorstenbosch

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Jose Antonio Gracia wrote:
>
>                 You know C.I. MC14499?
> Attached scheme in format BMP compressed with ARJ and auto-executable
> It is possible to connect several in series.

What?!?!

Using BMP (a Windoze specific format) compressed with a self-extracting
ARJ (a DOS executable) on the piclist?

First of all, you should not be posting binaries to this list -- many
people object to receiving very large emails like that.  Secondly,
surely GIF would be a more appropriate format -- one that can be decoded
on any machine that can run a web-browser, not just Windoze based ones.
Think of the millions of people not running a PC, or running a PC under
Linux.

Frank
------------------------------------------------------------------------
Frank A. Vorstenbosch     <SPAM_ACCEPT="NONE">    Phone: 0181 - 636 3000
Electronics and Software Engineer                 Mobile: 0976 - 430 569
Eidos Technologies Ltd., Wimbledon, London        Email: TakeThisOuTfavEraseMEspamspam_OUTeidos.co.uk

1998\07\21@065045 by Jose Antonio Gracia

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part 0 1791 bytes content-type:text/plain

Frank A. Vorstenbosch escribi—:

{Quote hidden}

Pardon Frank. I am new in the list.New attached in format GIF.
Thanks for your explanations.

--
Un saludo a todos
               Jose Antonio Gracia

jgraneEraseMEspam.....colon.net
http://www.geocities.com/SiliconValley/Pines/7097


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1998\07\22@105458 by paulb

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Frank A. Vorstenbosch wrote:

> Using BMP (a Windoze specific format) compressed with a self-
> extracting ARJ (a DOS executable) on the piclist?

 Could be *much* worse.  At least he didn't post the .BMP ;-)  It's
been done more than once!

> First of all, you should not be posting binaries to this list -- many
> people object to receiving very large emails like that.

 Many people object to most things!  Others have a descriptive term
for them.

> Secondly, surely GIF would be a more appropriate format -- one that
> can be decoded on any machine that can run a web-browser, not just
> Windoze based ones.

 This is true, but conflicts with the previous dictum.  Had he used a
better compression algorithm for the task, such as LHArc, he would have
compressed the graphic to only 4943 bytes; a figure so comparable to the
average size of an e-mail that only a professional whinger would object.
As it is, his GIF was a mere 8131 bytes.  (The ARJ SFX was 22,582 by way
of reference and the BMP - 349206!)

> Think of the millions of people not running a PC,

 Is it not hundreds of millions not running a PC?  Or do you mean the
minority *on the internet* not running a PC?

> or running a PC under Linux.

 Can you not get LHA and even ARJ for Linux?  SFXs are unnecessary and
violate commonsense anyway, even if they are not platform-limiting.

--
 Cheers,
       Paul B.

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