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LCD Issues

by sillygreen on Thu May 30, 2013 3:14 am

I bought an LCD variety pack and got a 16x1 character display with a HD44780A00 controller chip. In attempting to follow the LCD tutorial I can get the LCD to power on and control the contrast, but that is it. The screen shows 8 black boxes with the contrast at max so I don't think it's broken. I wired the LCD according to the tutorial and I get no reaction from the screen when uploading code. I've attempted to use the screen in 8-bit and 4-bit mode with the same results, those 8 boxes never change. I've adjusted my contrast to both extremes and everywhere in the middle. I even attempted to manually initialize the screen by sending the appropriate data bits as noted by the HD44780A00 datasheet, still nothing. Does anyone have any ideas of what I could try? The issue seems to be initializing the screen. The 3 screen pack was only 5 dollars, so it won't be a huge loss if I can't get this working, but if I didn't try everything it would haunt me.
sillygreen
 
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Re: LCD Issues

by floresta on Thu May 30, 2013 9:36 am

The issue seems to be initializing the screen.

If your 16x1 display has only one controller chip then it is actually configured as an 8x2 display. Change your lcd.begin() statement to reflect this configuration and remember to reposition the cursor to display the second group of 8 characters.

For all the gory details you can follow the LCD Addressing link at http://web.alfredstate.edu/weimandn.

Don
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Re: LCD Issues

by sillygreen on Thu May 30, 2013 11:25 am

I've tried that with no luck. The screen doesn't appear to be receiving any data, wouldn't the display change in some way if it was? I think I'll chalk this one up to a busted display as I can't find any troubleshooting steps that I have not attempted including the initialization by instruction detailed in that link. Thanks for the reply.
sillygreen
 
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Re: LCD Issues

by floresta on Thu May 30, 2013 12:53 pm

Since you are getting the 8 blocks to show up on the display there is a good chance that the display is not defective.

The LiquidCrystal library does do the 'initialization by instruction' so that is not the problem.

Most likely you have some sort of wiring problem. Make sure that the numbers inside your LiquidCrystal lcd(...) statement match the pin numbers that you are actually using and make sure that you didn't forget to connect LCD pin 5 to GND.

Don
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Re: LCD Issues

by sillygreen on Thu May 30, 2013 1:50 pm

I have checked my wiring more times than I can count. The rs pin is on arduino pin 2, rw pin to ground, en pin to arduino pin 3, D4-D7 are on arduino pins 4-7. My lcd variable declaration is LiquidCrystal lcd(2,3,4,5,6,7). At work now, I'll post a picture of my wiring when I'm home.
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Re: LCD Issues

by sillygreen on Thu May 30, 2013 4:27 pm

As a point of interest the lcd module has 16 pins though it does not appear to have a backlight or the led is blown, applying 5v and GND to pins 15 and 16 respectively makes no change to the module.
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