LCD-00791 software driver problem

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rgsparber
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LCD-00791 software driver problem

Post by rgsparber » Tue Jul 04, 2017 4:43 pm

I bought an LCD-00791 16X2 display and it worked fine in 2015. I just wrote some new code that uses this display and find that I can't move to the second row. Anything that is printed appears on the first row. "lcd.setCursor(0,1);" has no effect.

I do have lcd.begin(16,2); in my setup(). I'm driving the display with a Pro Micro. Printed characters are correct.

I understand that this is a discontinued product but hope that the drivers are still available.

Help would be greatly appreciated!

Thanks,

Rick
PS: I'm also having no joy with an MCP23017 port expander that runs via I2C but don't think it is related.

rgsparber
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Re: LCD-00791 software driver problem

Post by rgsparber » Wed Jul 05, 2017 12:21 pm

I doubt this is the right way to do it, but I modified LiquidCrystal.h at line 75 from begin(16,1); which says 16 columns and 1 row to begin(16,2); which says 16 columns 2 rows. Display now works as expected. It is not at all clear why I had to do this.

Rick

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Ross Robotics
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Re: LCD-00791 software driver problem

Post by Ross Robotics » Wed Jul 05, 2017 7:22 pm

That is odd. Not sure why either..
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lyndon
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Re: LCD-00791 software driver problem

Post by lyndon » Thu Jul 06, 2017 11:02 am

Did you update your Arduino libraries in that time? I'm trying to debug a similar problem remotely. My code works just fine at my site, but at the overseas site, the same display does weird things. The actual display over there was working before I updated libraries.

If you figure out the answer, I'd really like to know. It's a puzzle.

rgsparber
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Re: LCD-00791 software driver problem

Post by rgsparber » Fri Jul 07, 2017 11:01 am

I did not update my library AFAIK.

Are you sure the overseas site has the same hardware configuration? A broken wire or misplaced wire can cause strange results. It is not unheard of that around the time of a software update, a wire breaks. I suggest you go back to basics and assume that it never worked. Check every connection and then check the version of each software component. If that is the same as at home, try downloading the code again.

Rick

lyndon
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Re: LCD-00791 software driver problem

Post by lyndon » Mon Jul 10, 2017 9:42 am

Thanks, but we've already troubleshot the hardware. It's definitely a software problem. Most likely culprit is that there's an existing software bug, but it only shows up on the remote site since it has a slightly different display board.

Anthony Fremont
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Re: LCD-00791 software driver problem

Post by Anthony Fremont » Thu Jul 20, 2017 7:30 am

I have an older Hitachi based LCD that needs a longer reset period than the datasheet would indicate. It wouldn't work with the library default. Perhaps you have a similar issue.

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