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### Topic: Reading LCD Datasheet Schematic (Read 1 time)previous topic - next topic

#### afhaque89

##### Mar 29, 2011, 04:28 pm
Hi everyone,

I'm trying to wire up my new LCD (NHD?0208AZ?FL?YBW). But so far I haven't gotten much more luck than getting the backlight turned on.

Here's something I'm unsure of... but might be the source of my problem. In the data sheet the following schematic is provided:

What exactly does it mean to have an arrow pointing directly to a resistor.. and what are those white arrows coming off on both sides of the resistor? I always thought white arrowheads meant go to ground but that doesn't quite make sense here.

Thanks for the help!

#### frank26080115

#1
##### Mar 29, 2011, 04:29 pm
http://en.wikipedia.org/wiki/Potentiometer
Freelance engineer, consultant, contractor. Graduated from UW in 2013.

#### afhaque89

#2
##### Mar 29, 2011, 05:02 pm
So it just means connect to potentiometer? (So I should be able to just go with a regular resistor instead right?)

And what the white arrow heads above and below the pot?

#### GaryP

#3
##### Mar 29, 2011, 05:04 pm
The little picture:
The one you see connected to GND, goes to... GND! Other one connected to Vcc, goes...?

Cheers,
Kari
The only law for me; Ohms Law: U=R*I       P=U*I
Note to self: "Damn! Why don't you just fix it!!!"

#### frank26080115

#4
##### Mar 29, 2011, 05:20 pm

So it just means connect to potentiometer? (So I should be able to just go with a regular resistor instead right?)

And what the white arrow heads above and below the pot?

The top arrow is probably Vcc (connect to 5V if it's a 5V LCD), and bottom arrow is ground.
Freelance engineer, consultant, contractor. Graduated from UW in 2013.

#### liudr

#5
##### Mar 29, 2011, 05:29 pm
The white arrows are confusing a bit. Just pretend they're not there. Get a potentiometer like this:

http://dipmicro.com/store/R4V10-3296

Connect its first pin to 5V, 3rd pin to GND, and the middle pin to LCD pin 3. Then turn the little sucker all the way one way and/or then the other way until you see a row of black boxes (not two rows).

#### floresta

#6
##### Mar 29, 2011, 05:47 pmLast Edit: Mar 29, 2011, 05:50 pm by floresta Reason: 1
Quote
The white arrows are confusing a bit. Just pretend they're not there.
Not true.  They indicate how the backlight gets its power.  There are arrows on the left as well as on the right.  The arrows pointing up are connected to one another and the arrows pointing down are connected to one another.

You do not want to try to implement the schematic that you got from the data sheet.  That schematic was drawn in the days of microprocessors that used external memory.  In that diagram the LCD is 'memory mapped' so that it looks like another memory chip to the microprocessor.

Don

#### floresta

#7
##### Mar 29, 2011, 06:00 pm
Quote
What exactly does it mean to have an arrow pointing directly to a resistor
I'm not sure that you have figured this out yet.  This is not a arrow pointing to a resistor it is the symbol for a three terminal device called a potentiometer.

Don

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