Is there a way i can wire a calculator to the arduino so that when the numbers on the calculator are pressed in a certain order it sends a signal to a led or somet help! :-[
You'll need to understand how the calculator detects button presses.
After you've figured that out, it'll be a simple matter of adding some wires to connect to inputs, and then some code to detect it.
The calculator probably uses a button matrix. You may want to start there.
Do you actually want the calculator bit or is it just the keypad? If the latter then look:- http://www.arduino.cc/playground/Code/Keypad
Thanks for the replies im chekin the web address out at the moment i do want the circuit board and the keypad bit.
i am a compleate newbie and i dont no what your on about when u say i have to
how the calculator detects button presses.
Most calculator have a processor in them that scans the keyboard matrix. This means it is difficult to tap into one and just have a key press detected. There is a bit of investigation to see exactly how your calculator is accessing the keys. This normally involves looking at signals with an oscilloscope. If you are a complete beginner or have no access to a scope I suggest you find a local group who can help you. It's not the sort of thing you can do over the internet as you need to measure signals.
Okay. Listen closely.
Firstly, press a few buttons and stick your multimeter to near the button leads (if you can get at them) and see if you get volts and trace the current to where it ends up and then solder wires from there.
That probably won't work if you're calculator wasn't made 10-15 years ago. Then, download this: http://accrochages.drone.ws/en/node/90 and stick it onto your arduino. Next, do something similar to the the multimeter and check for any waves at all. After poking at quite a few buttons you should be able to trace the current and solder wires onto the board that lead to your arduino. Then, if you don't know how to read input, read the tutorials on the website and don't look back until you're done. Finally, it should pretty simple. Read input from the buttons, and "parse" it and do whatever you want with the input you get.
Thanks Poincare This Helps Loads!! :D