[AVR] Problem with lcd contrast

[Mohsen6265]

the characters are almost invisible. i tried connecting pin 3 of the LCD to ground directly but it wouldnt work and ive tried using pot but its still not working can any body help?
i need to add that when the pin 3 is connected to ground i get the max contrast which is still invisible.

 

[KlausST]

Hi,

How can we help? We even don´t know which LCD you refer to.

And if we have the information, then we need to read the datasheet to tell you what is written in there.
Best is if you read the datasheet by your own.
Then if there any doubts you should give detailed informations about LCD manufacturer, LCD exact type, Document section you refer to...

Klaus

 

[FvM]

You might have a LCD expecting a negative polarisation voltage, e.g. 3.3V type.

 

[Mohsen6265]

this is the lcd im using:ts1620a-20 and here is the datasheet:https://www.pazhelec.com/download.php?download=catalog&id=390
based on what i figured out i think the pin 3 needs a pot between VCC and GND but its not working so i might have made a mistake, can u take a look at it plz and tell me what u think.

 

[FvM]

Corrupted link (shortened with ...)

It seems to be a 5V display. Did you manage to power the backlight? Otherwise the contrast would be pretty poor, I presume...

 

[Mohsen6265]

yes the back light is working perfectly. sorry about link let me give u a better one:
https://www.datasheetspdf.com/datasheet/TS1620.html
i hope it works

 

[FvM]

I don't see a datasheet for ts1620a-20 under your link. I also notice that the device is offered by different manufacturers, ts1620 seems to be a kind of collective term.

I believe the question has been answered as far as we can. It's obviously a 5V device, expected to work with typically up to 5V polarisation voltage (measured between Vdd and V0). I found a typical polarisation voltage of 5V mentioned in a ts1620-1 datasheet, means the wiper would be typically near the GND pot end.

Did you check the actual polarisation voltage with a meter? According to maximum ratings, V0 can be supplied with a negative voltage (up to 11V below VDD), if the contrast can be improved with a polarisation voltage above 5V, you have probably got a device with rather marginal specification. Or it's simply defective.

 

[Mohsen6265]

thx for the help buddy u have been helpfull.
i figured out the problem and u were right, my regulater had problem and the out put voltage was lower than what it was supposed to be now that i connected the power source directly to the micro its working fine.
thx again for the help.