No data on LCD

Hi Guys,

Remember in this thread: Arduino Forum - I apologised in advance for any silly questions... Well..... :slight_smile:

I've received my wonderful arduino and i'm having some trouble getting my 16x2 LCD to display any text at all. Here's the setup

Board: Arduino Uno (powered by USB)

Sketch: LiquidCrystal "Hello World", Blink, Serial etc etc ( all of em in fact :wink: )

LCD: CrystalFontz America CFAH1602B-TMI-JT - 16x2 white on blue (because it's prettier than black/green hehe :slight_smile: )


The arduino is providing +5v and GND to the two power rails on my breadboard.

Pins 11, 12 are hooked up to LCD pins 4 and 6
Pins 5,4,3,2 are hooked up to LCD pins 11,12,13,14 respectively

LCD Pin 5 (R/W) is hooked up to the common gnd rail
Pins 15 and 16 are hooked up to +5v (w/resistor) and GND for the backlight

LCD Pin 1 : Ground
LCD Pin 2 : +5v

10K pot is hooked to +5v, GND, and wiper is to LCD pin 3

Turning the arduino on lights up the screen, and adjusting the pot for the contrast seems to work. The pot has 10 slight "clicks" around from one end to the other. It will sit half in, half out of these clicks however. So

Position 0 : nothing displayed on the LCD
Position 5 : still nothing displayed on the LCD
Position 7 : the blocks are starting to show
Position 8 : top row of blocks are solid white, second row is faint black/blue
Position 9 : Two rows of white blocks
Position 10: No change from pos 9

The problem lies in getting data from the arduino to the screen. No matter which LiquidCrystal sketch i upload, same result.. Nothing is displayed. - Just to be on the safe side, I've redone all the connections on the breadboard three times, and also checked for continuity between the end of the wire, and the pad on the LCD. All connected through without a problem.

The datasheet does say:

This module uses a Sitronix ST7066U controller. The Sitronix ST7066U is compatible with the industry standard Hitachi
HD44780 controller. Software written for modules that use the HD44780 should work without modification.

I'm just wondering if anyone has any ideas at all. I'm at my wits end and I fear the arduino is actually mocking me on purpose!

Thanks :slight_smile:


I don't see any reference to pins 2 and 1 on the LCD - power and ground.

Hi Mike,

Yeah, sorry. I missed them out. They are indeed connected. Pin 1 to GND - Pin 2 to +5v

I'll update my first post to reflect that



Try removing the +5v from one end of the contrast pot.

Okay. Removed the +5v from the pot, and still no data.. But, the pot screen now shows faint blocks when at position zero. Seems like it has a better range now

At position 0 on the pot, there is one faint line of blocks, then a fainter line beneath (barely visible)

Stay at position 8 and show us your code and pictures. The LCD is working but it is not receiving correct commands. Go buy another pot (10KOhm) that is not dedented (no clicks just smooth turns).