16x2 LCD powerup question.

jai · Joined: 12 Apr 2011 Posts: 11

Hi All,

I am working on a project where the display is JHD-162A. Which is a 16x2 line LCD module.
It works fine. The problem is when i turn power on first it displays black box on one line. After that it works fine. My question is how can i avoid that.
I just want the display to be blank at power on.
I also found that it does not have anything to with LCD init as the problems occur even when i don't program to use the LCD.

Thanks for any help,

Regards
Jai.

jai · Joined: 12 Apr 2011 Posts: 11

I found that the VEE voltage was 0 Volt.
When i increase the voltage to greater than 0.5 Volt.
Some of the characters do not properly appear.

Regards
Jai

temtronic · Posted: Thu Jun 30, 2011 8:17 am

All(most) LCDs have an internal powerup sequence and a default setting(usually 1 line).The LCD manual will explain this.
You can't get around this unless you reprogram the LCD chip itself which is not an option.

This procedure is inside the LCD, it does not have anything to do with the driver you use.

The LCD 'contrast' pin (usually pin 3) has to be adjusted for the best 'look' based on the angle the viewer will see it from. Most LCD modules will have a pot allowing you to 'set once and forget' this adjustment.

hth

jai · Joined: 12 Apr 2011 Posts: 11

Thanks for the input.

regards,
jai.

foxOnTheRun · Joined: 17 Apr 2010 Posts: 43

Hi, the black line appears if the LCD is not receiving an init sequence, to avoid this I do in my code:

lcd_init();
setup_oscillator(OSC_8MHZ);

rst(); // initialize vars, counters, etc

And the display is immediately driven, so no garbage is actually displayed

;)
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