Ok, so while thinking about it some more I decided to try to detach the interrupt befor doing anything LCD related..... and sure enough that has "worked".  I would prefer not to have to do this though, does anyone know why or how to prevent this?

Thanks,
Josh

First, a disclaimer - I'm new to this and could be way off on my diagnosis - but I need help.  I have some very simple code that tries to use an interrupt using the "attachInterrupt", and also interfaces to an LCD using the 4-bit library.  If I don't attach an interrupt - everything runs fine without any issues, looping on into infinity.  If in the setup I attachInterrupt to either 0 or 1, first or last thing I do in setup, etc. - The loop will run, but after a few itterations through the loop - it will stop and hang the board.

If I remove all other code for the LCD except for the "lcd.init()" - everything still works fine - it seems that it is only an issue if inside the loop I try to do anything to the LCD - even an "lcd.clear" will eventually cause everything to hang.  I'm confident all my wiring is correct as everything works fine until I try and attach an interrupt.

Any thoughts?  Do you need code examples or hardware diagrams to know?  I am just doing the basic 4-bit LCD stuff, and almost nothing else at all.

Thanks,
Josh

Thanks for all the help, I was able to find lots of options including the one you provided which sent me in the right direction.  I think I can really lower my costs - and later might consider something like this for an I2C I/O expander:

http://www.sparkfun.com/commerce/product_info.php?products_id=8130

Now I'm just trying to find a relay that is cheaper then what I have found so far.  $10 per relay, needing 16 relays.... thats a lot more then I wanted to spend.

Where do you all shop for parts?

Thanks again,
Josh

Yes, that is helpful, and I totally agree about the waste of money (it gets up there for sure).  I would love to not need to use something similar, but I need all 16 relays where as as you described I could get 12 with Arduino by using every single digital pin.  I did not mention earlier, but I also need 2 pins for a planned serial LCD and 2 more for a keypad (or maybe not depending on how I use the keypad).  This would limit me to even less relays.

Perhaps my question should be - How did they do this serialy addressible board, and could I do it with Arduino? -  So I can make my own.

 - OR -

 How can I address 16 relays and still leave room for 2 other serial devices?

After looking around some - I think I want an I2C setup:

http://en.wikipedia.org/wiki/I2C

I have more reading to do there, and may find my own answer, but can anyone point me to an example for this on anArduino?

Thanks so much for the help and the quick reply!


-- Josh

Ok, so I'm very new to all of this so please excuse what may be a silly noob question, but before I purchase an Arduino and start playing around - I'm wondering how hard it would be to interface with the "RC-4" from EFX-TEK:

http://www.efx-tek.com/topics/rc-4.html

I ask because I'm not sure how to build something like the RC-4 (is it easy?), and it seems simple enough to interface with one of the Parallax Basic Stamps which I was thinking of purchasing prior to finding the Arduino.

I did a lot of "googling" and searching and could not find anyone already doing this - so any help or suggestions would be great.  One of the main reasons I'm looking at the RC-4 is because you can chain up to 4 together and control them all with just I/O – and for my application I need a lot of power control.

Thanks,
Josh