Searching \ for 'Driving LCDs' in subject line. ()
Make payments with PayPal - it's fast, free and secure! Help us get a faster server
FAQ page: www.piclist.com/techref/lcds.htm?key=lcd
Search entire site for: 'Driving LCDs'.

Truncated match.
PICList Thread
'Driving LCDs'
1998\01\18@134246 by Rock Thompson

picon face
I'd appreciate any suggestions on inexpensive LCD drivers to use with
a PIC.  I'm building an exercise computer with three 4 digit LCDs (7
segment). I think that's too many to drive directly with the PIC, and
the PIC with a built-in LCD driver is expensive (and I guess I'd need
one for each LCD).

I'm thinking of a 16F84 controlling three LCD drivers or maybe one
driver multiplexed amoung the three LCDs.
This is my first project using LCDs (for low power) and the blasted
things seem more complicated than LEDs.  Which drivers and method make
sense to use?

I am so consumed with designing this that I've given up exercising
until it is done.  I'm turning to fat even as you read this.  Please
help.
_________________________________________________________
DO YOU YAHOO!?
Get your free @yahoo.com address at http://mail.yahoo.com

1998\01\25@213105 by sam Haile

picon face
Hi
I have the same problem with my project
"talking clock"

my advice is use LED instead of LCD
if you want to use LCD you must know that
it require a backplane strobe pulse
to keep the display refreshed, otherwise it'll go blank.  This is
more difficult to impliment with the PIC because you really need to
use interupts to keep regular pulses so that the displays don't flicker.


by the way I would be interessted if you solve the problem

do email me back you have some tip for my project

sam

______________________________________________________
Get Your Private, Free Email at http://www.hotmail.com

1998\01\25@223851 by Bob Blick

face
flavicon
face
At 10:30 AM 1/18/98 -0800, you wrote:
>I'd appreciate any suggestions on inexpensive LCD drivers to use with
>a PIC.  I'm building an exercise computer with three 4 digit LCDs

How about the AY0438? It is like the LCD driver PIC without the PIC. $4 at
DigiKey, or thereabouts. Made by Microchip, even.

-bob

http://www.bobblick.com/

1998\01\26@002248 by rlunn

flavicon
face
> My advice is use LED instead of LCD.
> If you want to use LCD you must know that
> it requires a backplane strobe pulse to
> keep the display refreshed, otherwise
> it'll go blank.

       Yeah, but almost nobody actually bothers
       to drive an LCD _directly_.

       For a four-digit seven-segment LCD with
       one backplane I would use an MM5452 or
       MM5453, which drive 32 and 33 LCD segments
       respectively.

       These chips require only a resistor and
       capacitor (to produce the backplane strobe),
       and have a two-line interface to the micro-
       controller (clock and data).

       The comms protocol is trivial.

       For a four-digit seven-segment LCD with
       two backplanes I would use a PCF8577, which
       can drive up to 64 LCD segments.

       Again, only an RC pair is required, and the
       two-line interface is now IIC!  This allows
       the chip to share the comms bus with other
       devices (including other '8577s).

       The comms protocol is no longer trivial,
       but IIC software is readily available.

       As I recall, the original mailer needed to
       drive three LCD's...

       With '5453s this would require three chips,
       and they can't be connected to the same
       two clock and data lines.  They could share
       a data line, but would all need seperate
       clock lines.  This gives a total of four
       I/O lines required.

       With '8577s (and assuming static drive LCDs,
       that is, one backplane) three chips would
       again be needed.  But in this case all three
       chips could be connected to the same two-wire
       IIC bus and separately addressed.  So only
       two I/O lines required.

       Go to

               http://www.semiconductors.philips.com/search/

       to search for the PCF8577 data sheet (.pdf).

___Bob

1998\01\26@041026 by Mike Ghormley

flavicon
face
Rock wrote:

>I'm building an exercise computer with three 4 digit LCDs (7 segment). I think
>that's too many to drive directly with the PIC, and the PIC with a built-in LCD
>driver is expensive (and I guess I'd need one for each LCD).

I have used the Telcom TC7211 chip a long time ago.  It is a four-digit
7-segment
LCD controller.  I believe that MAXIM is now making (or at least second-sourcing
the chip) as ICM7211.  I've no idea on the price, but I have used these and the
ICM7218 (8-digit 7-segment LED Mux/Decoder/Driver) with success.

It (the `7211) uses a four-bit data bus and four seperate digit select pins.
Of course you could reduce the pin count by two using some logic circuitry
between
two pic pins and the four select lines.

The data sheet in PDF format can be found at:
       http://209.1.238.250/arpdf/1675.pdf

Best of luck on your reducing program!  ;^)

Michael

/*******************************************************************************
\**  When the way of the Tao is forgotten, kindness and ethics must be taught.
**
**  Men must learn to pretend to be wise and good.  --  Lao Tzu
**
\*******************************************************************************
/

1998\01\26@075015 by WF AUTOMACAO

flavicon
face
Rock Thompson wrote:
>
> I'd appreciate any suggestions on inexpensive LCD drivers to use with
> a PIC.  I'm building an exercise computer with three 4 digit LCDs (7
> segment). I think that's too many to drive directly with the PIC, and
> the PIC with a built-in LCD driver is expensive (and I guess I'd need
> one for each LCD).
>
> I'm thinking of a 16F84 controlling three LCD drivers or maybe one
> driver multiplexed amoung the three LCDs.
> This is my first project using LCDs (for low power) and the blasted
> things seem more complicated than LEDs.  Which drivers and method make
> sense to use?
>
> I am so consumed with designing this that I've given up exercising
> until it is done.  I'm turning to fat even as you read this.  Please
> help.
> _________________________________________________________
> DO YOU YAHOO!?
> Get your free @yahoo.com address at http://mail.yahoo.com

I have done for PIC16F84 (I used the Tango for D.O.S for the Schematic)

(PIC16F84 WITH FOUR 7 SEGMENT DISPLAYS)

Do you want? :)))

MIGUEL.

1998\01\26@075210 by WF AUTOMACAO

flavicon
face
sam Haile wrote:
{Quote hidden}

I resolved the Flick with computed delay!

Miguel.

1998\01\26@103602 by Rajnish

flavicon
face
Hi Mike,
Would appreciate if you can send me your asm code for the ICM7218.
Rajnish.

At 01:08 AM 26/1/98 -0800, you wrote:
>Rock wrote:
>
> snip...... but I have used these and the
>ICM7218 (8-digit 7-segment LED Mux/Decoder/Driver) with success.
>
>Best of luck on your reducing program!  ;^)
>
>Michael

1998\01\27@130944 by Montaigne, Mike

flavicon
face
I would appreciate a copy of TANGO schematic and PIC code.
Also are you still using TANGO DOS or have you switched to something
else.
I am trying to decide what to switch to.
Mike Montaigne

{Quote hidden}

More... (looser matching)
- Last day of these posts
- In 1998 , 1999 only
- Today
- New search...