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Topic: How to control 2 graphic LCDs with one Arduino (Read 16012 times) previous topic - next topic


Hi Bill
I confirm that with your correction it is working fine in 128X128 configuration.
Thank a lot.


Raoul, Great. I've already added the correction to the library and will get out an updated library soon.
So will this dual display mode work for you?

For everyone else still following along. This "bug" only affects glcd configurations that use vertically stacked chips.
That is to say GLCDs that have more than one chip controlling the glcd in a vertical direction.
The common 128x64 or even 192x64 glcds are in a horizontal orientation and are not affected by this.

That said, the library should handle vertical chip splits properly so I'll be posting an updated
library on the google code site (project glcd-arduino) that includes the updated code to fix this soon.

The reason that Raoul was seeing this bug using 128x64 glcds,
is that in a dual glcd module configuration where two 128x64 glcds are configure as one
"big" 128x128 glcd, there will be both horizontal and vertical chip splits.
The horizontal splits are on each glcd module, and the vertical splits are between the two modules.

--- bill



I am still reading through all the posts in this topic and others about the GLCD library.
I posted about 2 years ago about compatibility with some displays I have. I think the library then was revision 0.1 and was related to the SED1520.

My displays are EA DIP122-5NLED and are 122x32 and feature a chip which is compatible with the SED1520.

The reason for posting on this topic is the dual display question.
I am building my own version of a home power/energy monitor and I would like it to feature 2 of the displays I have.

I am not sure if anyone has had this working with the SED1520 based displays or not, I still have a bit of reading to do yet.

Tonight I am going to pull the displays out and have a play with them, see if I can get anything working.
I have had the displays for about 3 years but never used them.

Hopefully the GLCD library will work ok with this particular display, it would be nice to utilise the displays.



Got 1 Display working, as per the main topic about GLCD.
Question remains about 2, but thought I would repost saying I got it working with 1 which is the first step.

Thanks for the great library.


If you don't mind using an extra chip per display, you could have a lot of them. I did an article about driving graphical LCD displays using I2C or SPI here:


With I2C you could potentially have 8 displays (since you share the same 2 pins: SDA/SCL) and you can configure the chip to have up to 8 addresses. With SPI you can have as many displays as you can spare SS pins for (3 wires for MOSI/MISO/SCK plus one extra one for SS per display).

With a Mega you might not need to bother because you have some spare pins, but it is an idea.

Awesome! I will be switching over to I2C GLCD control asap!  This will save me the expense of buying a mega just to get more I/O points. :)

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