Connection of LCD display with avr

[sazzad7]

I have declared port B of atmega8 for LCD display. I have connected portB.0 to portB.3 with lcd's pin D4 to D7 and RS with portB.4 and E with portB.5 . R/W pin of LCD is grounded. But the problem is i didnt get any out put from LCD. Should i connect LCD'S pin D0 to D3 with ground? Note: programme simulation is ok!

 

[wkrug]

What do you see on Your Display?.
When the Initialisation fail's there shoud be a black bar visible.
When there is nothing to see you should check the contrast adjustment and the Supply Voltages of the Display.

The Software must fit to the connections of the Display. Have You checked your used library?

 

[sazzad7]

Thanks for your reply.
There is nothing on the dislplay. I gave supply voltage= 5v and contrast voltage= 2v. I also applied 5v on the contrast voltage but no result. Yes, i checked the library and proteus simulation is successful. Should i grounded data pin d0 to d3 or unconnected?

 

[wkrug]

Normally it doesnt matter if the D0..D3 Pin are grounded or not.
Try to put the Contrast Pin neally to GND. Most Displays need there a very low Voltage until down to Ground, or a little negative Voltage.
That's depending of the Display and should be a Part oft the Datasheet.

 

[sazzad7]

Yes you are right. I applied nearly zero voltage to the contrast pin and it shows squer box on the lcd display but contrast intensity of lower line is greater than upper line and another problem is when i connect the display with microcontroller the display becomes totally blank again

 

[wkrug]

When the Bar at the 1st Lind disappear, the Display is initializied in any matter.
The contrast setting before and after Initializing of Display are different.
Try to Display some Text on the Display and readjust the contrast voltage again.

Without Initializing the first Line of the Display should Show a black Bar, the second becomes blank.

That with the Bar is depending, how the Display controller is connected to the LCD.
Some show an half Bar at the first and the second Line, other do a full Bar at the First and a Blank Line at the second.

Look if the Port's of the ATMEGA are conected right manner, right direction ( input Output? ) and not used for other Functions like debug Wire, Fosz out and so on.
Some of that functions can be enabled in the Fuse settings.

 

[sazzad7]

Thanks bro

 

[sazzad7]

At last i got text from the display. But contrast is too low although i applied less than one voltage to the contrast pin. Is that for back light of the display? I applied 5v to the back light. Thanks for your help.

 

[wkrug]

When the Display has an Backlight Option, there are 2 additional pins at the Connector.
Most they called A(node) and C(athode).
Some Displays had integrated Resistors for the Backlight, at most Displays you have to apply the Resistor external.
The Current goes from 10mA up to 100mA maximum value. The exact Value for Your display can be found in the datasheet the display.