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[on:]

Hi all!

At our architecure lab at the University of Leuven we'll be building a sort of media facade in the forthcoming weeks, with - preferably - 3 graphical LCDs (Newhaven Display or the like). We try to avoid having three microcontrollers, each controlling one screen, and as such are now looking for a driver that handles multiple displays. Do these exist? Are there other alternatives that we might have to look into? Is daisy chaining Arduinos (i2c) an option, in terms of performance and cost?

Any help is greatly appreciated!

All the best,
Niels

[Reply #1 on:]

The standard KS0108 GLCD library has been used to control two or more GLCDs. For other displays, I suppose it's doable but provide what exact display you will use.

[Reply #2 on:]

If you use 3 serial displays that will make your life easy.
(vs 3 parallel interface displays)

[Reply #3 on:]

Thanks for the assistance guys! Thing is we really want to work with graphical LCDs, preferably like http://www.newhavendisplay.com/index.php?main_page=product_info&cPath=21_107&products_id=3295. In this case, I think the most feasible option is to daisy-chain Arduinos?

All the best,
Niels

[Reply #4 on:]

I'm sucessfully using buffers to drive multiple LCD's. Such as 74HC241. If you set OE pin low, first LCD is receiving, when OE high, second. Use more for more outputs.
Also if I'm not wrong it should be able to provide 3.3v logic from 5v if needed for the GLCD.
This way you can drive multiple LCDs, but only one at a time.

[Reply #5 on:]

I'm sucessfully using buffers to drive multiple LCD's. Such as 74HC241. If you set OE pin low, first LCD is receiving, when OE high, second. Use more for more outputs.
Also if I'm not wrong it should be able to provide 3.3v logic from 5v if needed for the GLCD.
This way you can drive multiple LCDs, but only one at a time.

How good was refresh rate? Can you notice the screens are refreshed one at a time?

[Reply #6 on:]

Do you need all 3 updating at the same time?
If not, connect them all in parallel and have 3 seperate CS/ control lines so you only one sees commands at a time - unless you want all 3 to receive the same command.

[Reply #7 on:]

You can't. The old data will stay on the display until you "update" it. Therefore if you don't update the LCD and will be sending to the second one, the first LCD will keep displaying whatever was send to it before.
Check the refresh rate of one display and then divide it by three (or how many displays you use at the same time). Another thing is, if you don't need all data refreshed, you're just updating part of the data on the display and it is much quicker.
On my current project I'm sucessfully sending data using 74HC241  to 4x TLC5925 (serial), 1xTLC5940(serial + GSClock) and 1x 40x2 LCD (RS, RW, E, D4 - D7)  and still have enough IO pins to connect and read 23 switches (voltage divider and use of 2 analog pins), DS1307, DHT11 and have  for proximity sensor (with 555) connected to 1x Arduino UNO.
Notice, that the OE on the 241 is negated on the second half. It'll save you another pin