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Connecting a graphical LCD via a I2C/SPI using a 16-bit port expander

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Posted by Tristec   (1 post)  [Biography] bio
Date Reply #15 on Sun 25 Mar 2012 09:44 AM (UTC)
Message
Hey Nick,

I have the same situation like moe: I cant see anything on screen, but the backlight with the poti is working.

I checked the connections several times but without solving the problem. Your I2C scanner printed "Found address: 32 (0x20)".

My LCD is labeled with "RT12864J-1" - the datasheet can be found here: http://www.satistronics.com/myfiles/file/LCD/RT12864J-1.pdf

Do you have an idea how to fix this problem, I would be very happy ;-)
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Posted by Nick Gammon   Australia  (21,391 posts)  [Biography] bio   Forum Administrator
Date Reply #16 on Mon 26 Mar 2012 03:36 AM (UTC)
Message
Without the hardware in front of me it's hard to say. Could be a timing issue. I would be measuring the data lines to make sure that they are clocking out what I expect to see.

- Nick Gammon

www.gammon.com.au, www.mushclient.com
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Posted by Moe69   (7 posts)  [Biography] bio
Date Reply #17 on Mon 26 Mar 2012 07:34 PM (UTC)
Message
hi there,

i bought a new expander chip, because i thought it was broken. but i got the same problems. theres nothing on screen, only white pixels with full contrast.
how can i change the timing of the output pins?

---moe
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Posted by Nick Gammon   Australia  (21,391 posts)  [Biography] bio   Forum Administrator
Date Reply #18 on Mon 26 Mar 2012 07:47 PM (UTC)
Message
I would be surprised if the chip was broken, I don't usually have problems with them.

You could try directly connecting the LCD to the processor, leaving the expander out for now, just to check the LCD is OK.

I think I had problems a while back with the backlight control. If it isn't right the characters can be impossible to see.

As for the timing, a brief delay between sending stuff might be required or it might arrive too fast for the LCD to store it.

- Nick Gammon

www.gammon.com.au, www.mushclient.com
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Posted by Nick Gammon   Australia  (21,391 posts)  [Biography] bio   Forum Administrator
Date Reply #19 on Tue 27 Mar 2012 04:54 AM (UTC)
Message
You are probably best off going to the Arduino forum:

http://arduino.cc/forum

... and ask there. There may be someone there who can say "ah I used LCD X and this is how I got it to work".

- Nick Gammon

www.gammon.com.au, www.mushclient.com
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Posted by Ijohnson   USA  (1 post)  [Biography] bio
Date Reply #20 on Wed 13 Jun 2012 05:09 PM (UTC)
Message
I have an HJ19264A 192x64 GLCD. I am trying to adapt this LCD to your libraries. It adds a third KS0108 chip. To "chip select" the proper chip, you must do as follows:

chip / pin CS0 CS1 CS2
chip 0 LOW HIGH HIGH
chip 1 HIGH LOW HIGH
chip 2 HIGH HIGH LOW

How can I implement this using your library?

Thanks!
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