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[General] LCD display doesn't function.

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karthi06

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Recently i have purchase a 16 by 2 lcd display,that is DT1602C. I connected the pins of lcd display to PIC and potentiometer.But the backlight newer turned on despite there is 5V voltage supply. My question is it HD44780 compatible ? Can it interface with a 5V pic and potentiometer ?

Thank you.
 

The backlight has nothing to do with the data interface and voltage, it is normally an array of LEDs connected to the end pins of the display connector. Are you saying the display is working but the backlight isn't lighting or there is nothing on the display at all?

Brian.
 

I connected the lcd display in a solderless breadboard and connected the pins to both PIC and potentiometer.I measured the VDD pin of LCD display using multimeter and it shows 5V when switch is turned on,but the lcd doesn't display anything.
 

For backlight connection you have to put a current limiting resistor in series with LED+ or LED- pins. If you gave 5V without current limiting resistor to LCD backlight then chanses are backlight is dead. Is LCD displaying text? See if you have made wrong connections like maybe you have used power supply pins as backlight pins and backlight pins as power supply pins.
 

Hi,

The controller chip used in that lcd is said to be hd44780 compatible.

Perhaps its nothing to do with the hardware, have you proven your software on another display ?

Why don't you post a picture/schematic of your hardware and your program code so we can help more.
 

lcd display problem

Hi,

I have programmed to display simple 'hello' program into 16 by 2 lcd display.When i tested the,the code works well.But,when i tested the code in hardware,it just display a line of boxes,no 'hello' character can be seen.May i know why this happens.

Thank you.
 

re: lcd display problem

how you made the connections?
did you properly connected the contrast varying pin? its pin number is 3
If you short this pin to ground, dark boxes are seen. the recommended range of resistance to be connected is 1.5k to 2k
I am saying this by making LCD JHD162A as the reference.
 
re: lcd display problem

May be your contrast set to too high

Please post ISIS and code
 

re: lcd display problem

I connected the lcd to a potentiometer.The code doesn't seems to be the problem as i applied yhe same code used in proteus into hardware.It works in proteus buy just shows a line of black boxes in hardware.

Thank you.
 

re: lcd display problem

Which MCU is using and check configuration is correct otherwise we would not be able to help without checking code and isis
 

re: lcd display problem

I am using Pic 18f46k22 and i connected the mcu to the correct pins.

Thank you.
 

re: lcd display problem

how about configuration word
 

re: lcd display problem

What do you mean by configuration word ? Did you mean the coding ?

Thank you.
 

re: lcd display problem

As you are using mikroC PRO PIC Compiler CONFIG words are set automatically by mikroC compiler. You can see the CONFIG words in Project>Edit Project... dialog box.
 

re: lcd display problem

Check whether you are using busy flag method or enable strobe method for LCD programming. I think busy flag is most widely used and effective method.
 

re: lcd display problem

By varying the potentiometer, is there any response on the screen? any change in contrast?
 

re: lcd display problem

Use a 10k pot for Vee pin of LCD. Vary pot till you can see Text.
 

Re: lcd display problem

There are two possibilites here, either your circuit does not match the simulation, or the simulator is wrong.

Now modern simulators are seldom wrong if fed correct data, so the first thing to check is your circuit, the second thing to check is that you are simulating what you think you are simulating, in particular is the LCD module model in the simulator is the **EXACT** one you are using, lots of (more or less) compatable parts out there with sometimes subtle issues in the startup timing.

Can you deliberately introduce some delays in your code to make good and sure that you are meeting all the required setup and hold timings (Then use a scope or logic analyser to check you really are on real hardware).

Is your decoupling up to snuff, and is the lcd close enough to the board to keep ground bounce under control?
Just because your simulation works does not mean the real circuit done as a real layout will.

Regards, Dan.
 

Re: lcd display problem

Dan Mills said:
Now modern simulators are seldom wrong if fed correct data....
Click to expand...

Quite a naive statement.

Simulators can rarely, if ever, fully simulate real world hardware, even the best simulators have limitations.

There are numerous examples posted in this forum of designs which function as expected in Proteus, however do not function as expected when implemented in real hardware.




@karthi06

You have not posted either the schematic of your design or the current version of the code, please do so.

Without both the schematic and code it is difficult to offer relevant advice.

HD44780 compatible LCDs require specific delays for proper initialization and configuration.

Is the display similar to the attached image?



If so, a single row of black boxes typically indicates the LCD was not proper initialized or configured.


BigDog
 

Re: lcd display problem

You will note that I hedged that statement with something about correct data (Which includes correct models), and I have to admit the only time I would use a simulator for something like that would be if it was hooked to some sort of PLD and I wanted to run a testbench.

It has however been a long time since I have had a simulator fail to converge, and while they are only ever as good as the device (And board parasitic) models I would hate to do modern high speed design without computer support.

Regards, Dan.
 

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