Hi everyone, so this is a pretty frequent topic but I am having trouble with the 16x2 LCD.
I have wired up the 5 set up wires that should allow for contrast control and turning on the back light. I tried to get the display with the 2 rows of blocks to show up but despite the back light turning on and adjusting the contrast successfully with a 10k pot there are no blocks showing up and the screen just dims and brightens.
The LCD I am using are ones that have been around the lab different periods of times but I tried 3 different ones and the all have the same issue so either they are all broken or I am missing something. I am using a 220 ohm resistor for pin 15 and a 10k pot to pin 3. Piin 1 is 5V, pin 2 is ground, and pin 16 is ground.
My bad so I used the adafruit tutorial and because it was a frequent topic I assumed the 16x2 LCD was pretty decently known, I'll post some pics and links soon
Also the arduino portion hasn't really kicked into effect yet since the blocks don't show up in the first place so I don't really mention those connections
So
VSS is to 5V
VDD to ground
V0 has a 10k pot between 5V and Ground with the wiper leading into it
A has a 220 ohm resistor connected to it that leads to 5V
K is connected to ground
These connections are connected correctly and I everything works according to the tutorial up to the contrast step where blocks should appear
So I did connect the wiper and the the potentiometer works in changing the contrast of the lcd display. But in the tutorial it said blocks are supposed to appear as the contrast changes but as I turned the potentiometer to both ends only the contrast/brightness changed but the blocks never appeared. I’m suspecting it’s in lcd thing since no arduino is involved and the contrast portion works fine but I wanted another opinion in case I’m missing something
jesseye:
Hi everyone, so this is a pretty frequent topic but I am having trouble with the 16x2 LCD.
I have wired up the 5 set up wires that should allow for contrast control and turning on the back light. I tried to get the display with the 2 rows of blocks to show up but despite the back light turning on and adjusting the contrast successfully with a 10k pot there are no blocks showing up and the screen just dims and brightens.
The LCD I am using are ones that have been around the lab different periods of times but I tried 3 different ones and the all have the same issue so either they are all broken or I am missing something. I am using a 220 ohm resistor for pin 15 and a 10k pot to pin 3. Piin 1 is 5V, pin 2 is ground, and pin 16 is ground.
Does anyone have any ideas or suggestions?
What you are saying in the first paragraph does not make any sense at all. The potentiometer should have no effect on the brightness of the display. The display brightness is affected by the 220 ohm resistor. The potentiometer should only affect whether or not you can see the blocks and how dim or dark those blocks appear once you do see them.
You are absolutely right that was a real bad mistake on my part. I was mainly using my arduino sketch comments when I was checking (which were also flipped) and I guess I had a case of confirmation bias that twisted how I reread the tutorial. It works now, thank you for your help
Hey Don
So it seems that was actually an effect of me mixing up pin 1&2, rather adjusting the contrast of the 2 rows of blocks it actually adjusted the contrast of nearly the whole display. So rather than having blocks show up and fade out, practically the entire display was getting its contrast changed so it looked like the screen was getting brighter and dimmer. After fixing it I noticed the screen is a lot brighter than it ever was and now only the blocks come and fade rather than the whole display doing. Basically it was due to my careless mistake, and the thread helped clear that up. Thank you for your help
