Connecting multiple LCD modules

Forum 2005-2010 (read only) Hardware Interfacing
1

Hi there,

I'd like to use the Arduino to build a low-cost MIDI controller.
I'd like to use an LCD module to label each control, but the number of controls exceeds the width of LCD modules I can find.

I'll need to connect multiple LCD modules to get enough characters to label each control adequately. Is it possible to do this?

I'd thought perhaps that using a multiplexer might be a good idea to route the arduino serial output between the LCDs - but I worry about timing problems (especially since I'll need to send MIDI too).

2

Nope, sorry, it's not possible. You'll just have to give up your dream ;D

There are a couple of ways you could go: you could connect all the LCDs in parallel, and run a separate line to the "E" pin on each one. Or you could use I2C (either with a specialized LCD controller board, or one of the "port expander" chips, like this), and assign a different I2C address to each LCD.

Ran

3

I2C is a nice way to go for this.

127 devices on two signal wires, each independently controlled.

Check out something like this guy:
http://www.hvwtech.com/products_view.asp?ProductID=675

4

I like the "in parallel, with enable lines" approach. I might try this with a demultiplexer. I've read scary things about I2C - but that was around 5-6 years ago, so perhaps things are a little easier now.

I'm almost certain there won't be enough arduino pins to support all the buttons I require so I'll have to do some multiplexing somewhere. Maybe I2C could help in that regard too.

Thanks for the comments!