My first Arduino project.
Eventual goal: Internet users input text into an online form which is then displayed on a local LED scrolling message board (I know, it's been done - but I want to do it!). I've got webcams trained on the scroller so the user can see the changes.
Looking for: comments on early direction to take and overall initial approach. Internet connectivity isn't being addressed yet, just the control of the LED scrolling message board using an Arduino.
My wife picked up a fully functioning 7x72 scrolling LED message board at a rummage sale for $8 ("Big Message Light" manufactured by Aroa HK Ltd around 2004). The interface is a small built in keyboard (A-Z, 0-9, other control and special keys) and I can easily use it to input messages manually and scroll away merrily.
My first instincts are to use the existing LED scroller's hardware and controllers since they already are fully functional. I would use the Arduino as a substitute for the built in keyboard to control the device.
I open it up (very easy 8 screw box) and see that the tiny keyboard is sending information in a traditional keyboard way: when a key is pressed, two circuits are connected (I assume this is the keyboard matrix). There are soldered ribbon cables on each end of the keyboard circuit board, one with 7 inputs, one with 8 inputs. I'm pretty sure this is what is referred to as the keyboard matrix? When I connect an individual key's circuit (use a metal screwdriver to open the connection) it sends the appropriate letter. Each letter (key pressed) thus sends a signal to a built in controller that interprets (for example) CIRCUIT A7 and CIRCUIT B2 tells the controller to "show the letter 'G' on the display. Basically, 56 possible signals (commands) can be sent by the keyboard.
My initial approach is to interface my (in the mail) Arduino Duemilanove with the keyboard in order to send input. I'm not going to do it yet, but I'm thinking of just clipping the ribbon cables and teasing out the individual wires for testing as I proceed.
Am I correct in thinking that I can use the existing keyboard ribbon cable inputs (each individual wire) as Arduino outputs? Can I actually plug in individual wires from the ribbon cable and send a brief HIGH signal to activate display of a letter? Or, should I look into more sophisticated keyboard emulation?
The advice I'm seeking is general, including potential pitfalls that might fry my equipment (none of which costs much - it was only 8 bucks). Or other directions to explore (I'm looking at an IPAC keyboard emulator as another approach).
I'm more comfortable with hooking this up to the Internet once the Arduino can successfully control the LED scroller. But I don't play with hardware enough to be comfortable (yet) in physically mucking about.
Thanks in advance for any comments.
Parlo Italiano!