Idea for writing code for an Alarm system

hi all,

im currently working on a PIC based project and not too sure on how to write a bit of code for it. i'm doing an alarm system that uses a keypad code to arm/disarm the alarm.

when the alarm is armed and a presence is detected the alarm allows 10 seconds to enter the correct code to disarm it otherwise the alarm siren will go off.

i am not sure on how to write the code for when the alarm is armed, how can i scan the keypad and verify if the correct code is entered within 10 seconds with the process of checking the correct code and a 10 second countdown happening at the same time.

I am writing the code in PIC C. Any ideas based around PIC C code or PIC assembly code would be much appreciated.

Thanks

I would do something like,

Hope that helps.

Mike.

managed to find the solution to the problem. it ended up being the +5v wire that needed to be pulled out after the hardware had been programmed something to do with the pull up resistors. i had previously known about this but forgot since its been a year since i needed to program a keypad.