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Topic: [SOLVED] 128x64 LCD Guide. Can't see the components in Picture. Please identify. (Read 3 times) previous topic - next topic


There are two black-ringed white circles on the breadboard that I do not know what they are. Do they represent capacitors?

[Image Attached]

I have not found a decent wiring diagram for the larger LCDs. Anyone have something better than these?

This one isn't one I can use since it isn't for the Uno.

This is the LCD I have:

Thanks for the heads up in advance.


looks like potentiometers, one for contrast adjustment, one for backlight brightness, I'd use a 10 kohm one for the first and a 1 khom for the second
Freelance engineer, consultant, contractor. Graduated from UW in 2013.


I'm not sure why you think you can't use the diagram on the playground site.

The diagram with the black circles (potentiometers) has incorrect wiring for the contrast pot.
The contrast pot has 3 connections that needs to be wired like this:
leg------ vee
wiper--------------------- Vo
leg------ gnd

The diagram with the breadboard shows:
leg------ vo
wiper--------------------- vee
leg------ (not connected)

The pot wiring is described several times on the ks0108 playground page and in the html documentation included in the library.
The html documentation included in the glcd library can be viewed and searched with your web browser.
There is a wealth of additional information in the included html documentation that is not on the playground page or
in the included pdf documentation.

The display in the spec sheet you linked to is "Pinout A" in the wiring table that is on the playground page
and also in the HTML documentation included in the library.

The diagram you referenced from the playground page is correct for your glcd.
For your Arduino, you may need to hook up the glcd modules reset (glcd module pin 14) to
vcc using a resistor rather than hooking it up to the Arduino reset line - to avoid auto reset issues
on the UNO board.

If you prefer, you can use the wiring table rather than a wiring diagram to hook up the wires.
For the glcd your referenced, simply follow down the "Pinout A" column and wire up the pins
according to the Arduino pins referenced in the "Arduino 168" column.
So for example, if you look in the "Pinout A" column you can see that glcd module pin 4 is connected to
Arduino pin 8.

--- bill


I gave it a shot. I thought I had it but once I powered up the Uno board via USB, the power light comes on very dim then shuts off.
I am going to look over the connections once more. They looked right the second time I checked them. I switched the two legs on the pot, +5 and ground, but I don't think you can hook them up backwards, the two outside legs. They can be connected either way, right? I have One outside leg to 18, the other to 20 of the LCD. LCD pin 3 is connected to the center leg of the pot. The resistor I am using for the pin 19 of LCD is 330 ohm. I believe it's from left to right, orange, orange, brown, gold. I think the multiplier is brown. It's hard for me to tell if it's brown or red but I think it's brown.
The potentiometer is the one that came with the UNO kit. I believe it's the 10k one.

EDIT: Ok, I've redone the wiring completely and still same issue. Doesn't appear to be anything wrong with the Uno; I tested it with the wires removed. Lights ok.

Thanks in advance for any help.

EDIT: "hook up the glcd modules reset (glcd module pin 14) to
vcc using a resistor rather than hooking it up to the Arduino reset line "

Ok, I am going to try that. I was thinking resetting might be light on and off. But maybe it's happening so fast that the light appears off.


Ok, one thing I did find wrong was that LCD's pin 20 has to go to pot leg 3 AND ground.

Also, I now have the LCD's pin 14 passing through a 330 ohm resistor before going to reset on the arduino.

Same thing is occuring, the arduino's board lights come on and then fade off. Staying off.

I'm gonna keep researching.

THis is what I am following:

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