i am using 16*2 lcd diplay with arduino uno when i connect pins with lcd it led is on but nothing will display in the lcd screen.i am connected rs , enable, read/write, 4 digital pins .plzz how to fix it?
This topic has been split from another one as it involves a different problem
Please do not hijack topics
UKHeliBob:
This topic has been split from another one as it involves a different problemPlease do not hijack topics
sryyyy, i want solution. if u know about it plzz help me
can you get the back light work ?
Find an online tutorial to follow and say which it is ( post a link to it).
If that doesn't work, post your code and a wiring diagram.
Hi,
Welcome to the forum.
Please read the post at the start of any forum , entitled "How to use this Forum".
OR
http://forum.arduino.cc/index.php/topic,148850.0.html.
Then look down to item #7 about how to post your code.
It will be formatted in a scrolling window that makes it easier to read.
Can you please post a copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png?
Thanks.. Tom.. 
thiyagesh:
sryyyy, i want solution. if u know about it plzz help me
Please help us to help you by providing details.
Usually when nothing shows on the LCD it is because the brightness setting is not correct.
Deva_Rishi:
Usually when nothing shows on the LCD it is because the brightness setting is not correct.
Not really. The brightness of the backlight is seldom the issue.
Contrast on the other hand can be an issue, but a contrast issue is not nearly as common as a wiring issue from either incorrectly wiring it up or not matching the lcd constructor pin mappings to the actual wiring used.,
--- bill
Not really. The brightness of the backlight is seldom the issue.
Of course i meant the brightness of the LC, that you call that contrast is fine with me. The problem with that setting in particular is that it is less obvious (one tends to think of it as optional, and it requires a part that not everyone has lying around. Wiring everybody has, and usually one tends to double check those before posting on the forum (though admittedly not always) And a few more times after getting questions about it anyway. Mind you how many people have felt silly for posting here only to find they made a wiring issue is a lot. Anyway for the Brightness/Contrast of the LC you need a (trim-)pot anywhere in the order of 1K up to 100K should work (all it takes is a reference voltage.) Trying to do it with just loose resistors is sometimes the attempt, but that hardly eliminates it as a possible issue if you can not get it to work.
Deva_Rishi:
Of course i meant the brightness of the LC, that you call that contrast is fine with me.
It sounds like you may have meant contrast and are confusing brightness and contrast.
Brightness is not the same as contrast. They are distinctly different.
Terminology matters.
"Brightness" refers to the brightness of the backlight, contrast refers to the duty cycle of the pixels on the display.
They are very different and are controlled/adjusted in different ways using different pins on the LCD module.
While some people incorrectly refer to the intensity of the pixels as "brightness" there is no brightness level adjustment going on when contrast is adjusted.
The contrast adjustment is controlling the duty cycle of the pixels which can cause the pixels to appear to our eyes to be more intense or to fade away.
But again, there is no brightness adjustment going on when the contrast is adjusted.
When dealing with things at this level, terminology and small details very much matter.
Also, having watched users posts related to issues with LCDs for the past 12+ years, I can say that contrast and backlight control issues are not the top issues that users have.
Wiring issues is by far more common.
The most common wiring issues are forgetting to wire the r/w pin to ground, or wiring up pins incorrectly so that the pins in the lcd object constructor do no match the actual pins used.
This is why when there is an issue, the one of the most helpful things is code being used as well as a few photos to be able to verify the wiring and verify that the wiring matches the code.
--- bill
Also, having watched users posts related to issues with LCDs for the past 12+ years, I can say that contrast and backlight control issues are not the top issues that users have.
You should always provide the OP with the complete list. Why didn't you ? Now i had to add to it, and i didn't do that perfectly, which caused your response and mine and now yours again. I was just putting it on the list, and the few cases that i get involved it scores a decent percentage (decent enough to put on the list.) The backlight rarely is an issue, hence i didn't even consider the possible confusion. (and someone else had already put that on the list) The only issue i've seen with a backlight was my own, but further investigation revealed that not only wasn't it connected on the PCB, but it didn't actually have one (and then it doesn't work) Anyway we will find out (or not, not all respond with the final solution) what the issue is or was.
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