Open Source Some questions on what arduino can do - very simple nothing too technical

Ive used an arduino before but I didnt do the coding for it.

Can an arduino monitor an input and only run a certain script when it changes (a 5v in as PWM and do one action when it goes form 5v to 0v and a different action when it does the opposite).

If this is possible, would the cycle only involve checking the input every say 1 min and not run all the other code until it changes.

So basically with A as the input
when A goes from 5v to 0v then do X (or just when it goes to 0v)
when A goes from 0v to 5v then do Y (or just when it goes to 5v)

This might be a very fundamental question now that ive written it down

 

Just thinking the input would be a constant 5v, dont think thats a PWM though

 

arduino are basically AVR's. so it's very easy to code for.

two ways of doing this: pooling or interrupt.

-pooling:
flagX, flagY.
while{
if A = 0v then do X, raise flagX, lower flagY
if A = 5v then do Y, raise flagY, lower flagX
}

-interrupt:
set A as interrupt input (interrupt only triggers on change, IIRC.
ISR{
when A = 0v then do X
when A = 5v then do Y
}


of course, i could be talking rubbish. i've coded for AVR's, and i've read Arduino uses AVR as its programmable processor.

 

double poster

 

Ah this could be it, think this would work for what I want. thanks

 

quick google showed up this:
http://gonium.net/md/2006/12/20/handling-external-interrupts-with-arduino/

the code in AVR-GCC tutorial link at the end looks very familiar to me. it seems Arduino uses a non-standard C, which enforces a healthy coding structure. AVR is indeed the programmable chip, which uses GCC compiler and takes standard C (good coding structure will look very similar to Arduino's code, except most things are in Main, loops have to be done manually).

 

To the best of your knowledge I can use an interrupt to run any script that the board would run.

 

yes, interrupt service routines are just a built-in function that will run when the set trigger happens. it's same as any other function you write.