Author Topic: LCD Display (HD44780) Display Issue  (Read 1002 times)

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Offline RyltarTopic starter

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LCD Display (HD44780) Display Issue
« on: January 14, 2012, 01:44:59 PM »
I'm using webbotlib v2.08 c++ to work with a HD44780 compatible display (link) and I'm getting two full rows of rectangles.

I have it wired up same as I planned in the project designer and when I don't have the data lines connected, it only shows the one row of rectangles as expected.

I've tried both 4 and 8 control line modes on the LCD but the result is the same. I only see the rectangles on both lines.

Using the display.clear() or display.print( ... ) functions don't cause any change in the display. Once the axon/webbotlib inits the LCD, I've got the two lines.

Adjusting the contrast pot doesn't help either. I get the rectangles or nothing.

I noticed that there was one issue in a recent version of webbotlib (topic), but it sounds like I'm having a different one.

I tested the device on my Arduino board and can verify the display works.

Suggestions?

Update: Tried with .08 and same issue.
« Last Edit: January 14, 2012, 02:19:13 PM by Ryltar »

Offline Webbot

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Re: LCD Display (HD44780) Display Issue
« Reply #1 on: January 14, 2012, 07:53:40 PM »
The issue you linked to previously only applied to using all 8 data lines. So if you are using 4 then it should be fine. Make sure that you also connect ALL of the control lines as shown in PD (some folk think you don't need the R/W line so don't hook it up or just connect it to ground).
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Offline RyltarTopic starter

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Re: LCD Display (HD44780) Display Issue
« Reply #2 on: January 15, 2012, 08:30:35 PM »
I have all the pins plugged in as described in the PD. Tried several different locations along the axon to control it with power on analog 15. The display looks the same if I don't send a command to it and if I do. Any ideas on where to look next for debugging?

Offline Webbot

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Re: LCD Display (HD44780) Display Issue
« Reply #3 on: January 16, 2012, 06:17:56 PM »
Hmmm nothing immediately comes to mind. Others (and myself) have got it going ok. Given a bit more time I'll have a look at the datasheet for your device
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Offline RyltarTopic starter

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Re: LCD Display (HD44780) Display Issue
« Reply #4 on: January 17, 2012, 12:57:39 PM »
As I understand it, it should work just fine with webbotlib. It is HD44780 compatible, product information and arduino tests have shown that. I must be wiring something wrong then. How frustrating.

Offline Webbot

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Re: LCD Display (HD44780) Display Issue
« Reply #5 on: January 17, 2012, 04:54:45 PM »
Keep me (us) informed of any progress - just in case there is something I've missed in the docs etc.
Webbot Home: http://webbot.org.uk/
WebbotLib online docs: http://webbot.org.uk/WebbotLibDocs
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