Mac LCD

Information for using small character LCDs such as the HD44780 with Mac OS X, LCDproc and Growl. And other Apple and Mac USB stuff.

Thursday, April 14, 2005

LCD proposal cont'd

So, to implement this LCD Project on Mac OS X, I figured I would have to write a daemon or command line utility that would accept messages to display. Then write a bunch of scripts or clients to display server data, then have users make their own if they wanted. (Sort of like LCDproc.) Obviously this would be a pain, and have little usefulness for existing applications.

Then I discovered an application that is designed to take message notifications from applications and display them to a user. Growl will allow me to just code up a small "Display" plug-in and immediately, the LCD will be able to display noitifications from a whole list of supported applications.

This might turn out very useful and functional!

Thursday, April 7, 2005

LCD Project Proposal...

So I have this idea for a LCD controller project for my Mac.

  1. Take a USB -> IEEE 1284 parallel printer adapter, open it up and take off the centroncs connector.
  2. Connect it to a parallel character LCD which uses the Hitachi HD44780 controller.
  3. Write a program on the Mac to send data through usb to the LCD.

Why is this any different from all of the other LCD's I have seen?

Well, any LCDs designed for the Mac use a serial connection. May others use serial connections too. This would require a USB -> RS232 adapter . This doesn't seem very elegant considering the project this will be a part of (more to come...). Any that use USB are generally pretty expensive:

http://www.j-works.com/jsb815.html - $65 for just the controller!

http://www.usblcd.de/products/showprod.php4?gr=1&lang=en - 45 euro for the controller.

I imagine I should be able to make this for $10-$20.

potential problems:

  • The IEEE 1284 USB adapters are made for printing, and maybe this won't work with an lcd (I'm not sure this will be a problem).
  • writing to USB devices is a little less obvious to program than writing to serial devices using the darwin IOKit. I sould be able to work this out though. You just can't open up a terminal program and make it work though.
  • Parallel won't let me use a keypad on the device like a serial controller would. But hey, I can use usb, right?