What is this "Vo" pin for in 2x8 character LCD?

hkBattousai

Member

• Oct 14, 2010

• #1

Datasheet of the LCD:
**broken link removed**

The "Vo" is defined as "Power supply for LCD drive". What does it mean?
What should I connect to this pin?

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Second question;

Should I pull-up the voltage on LEDA, or give +5V directly?

 

Last edited: Oct 14, 2010

ARandomOWl

New Member

• Oct 14, 2010

• #2

Page 4 of the datasheet show how to connect it. It controls the LCD contrast.

As for the backlight. Check if the display includes an internal resistor, some do. If not use an external one.

 

Last edited: Oct 14, 2010

hkBattousai

Member

• Oct 14, 2010

• #3

Sorry, my bad, I didn't notice that figure in page 4.

So, I will connect a resistor between GND and Vo. The value of a resistor must be between 0 and 20kΩ. And the contrast will be dependent to its value.

 

ARandomOWl

New Member

• Oct 14, 2010

• #4

Use a pot as opposed to a fixed resistor.

 

Nigel Goodwin

Super Moderator

Most Helpful Member

• Oct 14, 2010

• #5

Yes, use a POT - if it's not set correctly you may be able to see absolutely nothing, and the setting is temperature dependent as well.

 

hkBattousai

Member

• Oct 14, 2010

• #6

What happens if I short circuit Vo with GND (i.e.; make POT value 0Ω)?

 

ARandomOWl

New Member

• Oct 14, 2010

• #7

As Nigel said it depends on the temperature. Most probably the screen will be completely black (or blank, can't remember which way it is).

 

Nigel Goodwin

Super Moderator

Most Helpful Member

• Oct 14, 2010

• #8

hkBattousai said:

What happens if I short circuit Vo with GND (i.e.; make POT value 0Ω)?

Click to expand...

It'll either give no display at all, or just solid black squares.

I would suggest you check my PIC LCD tutorial which explains how to use them, and how to connect them. I use a pot rather than a simple variable resistor, which seems a better solution.