simple LCD displays

[patroclus]

I've seen lots of info about using LCd displays, but I want to use some very simple and cheap LCDs, from some calculators, with just 1 line and 7 segment per char (not alphanumerical LCD, you know what I mean?)

how can I control these?

 

[john1]

Hi,

i think you will find that type are matrixed up,
sometimes all the segments are commoned up
and you operate the anode for the character you want.

You may need a dedicated chip to use it,
or be prepared for some fancy chip-logic.

John

 

[patroclus]

I can use PICs like 16F84, so I think it won't be a problem.
What I need to know if how I control this LCD displays, as it is not matrix display, but 8 digit, 7 segments per digit (the ones used in cheap calculators).

Does anyone know how, or knows where I can find the pinout function?

 

[aryajur]

There are some simple LCD modules available with an an integrated LCD controller. They are simple to interface to a controller or processor with a defined register set and operations.

I suggest u can check this out:
**broken link removed**

 

[John Sorensen]

Those kind of LCDs, just the glass, can either be very hard or very easy. I think what john1 was getting at is that large displays (with many segments) are kind of multiplexed. Not in the usual sense, it has to do with planes and duty cycles and complex controls and voltages. If you're extremely lucky, you might find one that has each segment brought out to a pin, then all you have to do is figure out which is which and apply a suitable voltage at an appropriate frequency, which is not critical.

Best bet, buy a cheap alphanumeric display with an onboard controller. They're like $3 or $4, less than you would pay for all the glue logic between your pic and the glass.

j.

 

[kitedude]

theres a good few out there to choose from. it really depends on what you want to use it for.
a 3 1/2 lcd display should only be a few euros. They have a very low power comsumption but ar every easy to blow.

 

[patroclus]

Well, I can't find any for less than 10 euros... and I have some LCD seven segments already. I just thought it was easy to drive, even easier than alphanumerical LCDs, but I see that there's little or no documentation at all..

 

[Sebi]

If You have LCD with independent segments pins, use a CD4543 LCD digit driver.

 

[patroclus]

well it seems not. The one I have here has 8 digits, but only 27 lines to drive... supose they're multiplexed or something

 

[Sebi]

This is a multiplexed type. The main problem: in this case need a staircase signal for DC-free driving. Without processor need a couple of IC-s.

 

[patroclus]

I can use 16F84 with no problem. This way would be posible?

 

[elec_lover]

Driving LCD 7 segment dis. is more complicated than a LED 7 segment dis.
read first part of this articles: **broken link removed** http://www.liquidcrystaltechnologies.com/DrivingShutter.htm **broken link removed**