help making a security system...

hey people... i am new to all this. I want to make a security system using arduino, LCD Display, pir motion sensor and buzzer.

first of all tell me that should i use arduino with atmega 328 or arduino with atmega 1280, also known as arduino mega.

i want that when the pir sensor senses a motion it should display a warning on the lcd along with a buzz through the busser.

please help me... thank you...

sounds like a fun starter project!

Well for your purposes, i think the 328 should suffice. What you made is all quite simple if you just go through the playground a bit and find what your looking for. As for the pir, theres some sample code here; http://www.arduino.cc/playground/Code/PIRsense

The lcd screen: http://www.sparkfun.com/commerce/product_info.php?products_id=9393 and the info to use it: http://www.arduino.cc/playground/Code/SLCD

and for the buzzer, either find a 5vdc buzzer, or perhaps use a relay with a louder buzzer, connected to an outside power source.

GOOD LUCK! and please keep us updated!

yeah... i have seen everythng in tha playground are. but there is everything in parts. like i know how to use the pir and buzzer seperately. but i dont know that how will it work collectively. what i mean to say is that i know how to make the buzzer work when the pir senses motion. but what i dont know is that how to display an alert on the lcd at the same time.

but what i dont know is that how to display an alert on the lcd at the same time.

Well, that’s the bit you should concentrate on.
If you know how to sound a buzzer in response to a stimulus from a PIR, then the same principle applies to displaying messages.

AtMega vs 328, well 328 seems to be fine if your alarm system only wants a few zones. 1 out for the buzzer, 1 out for the serial display, and still plenty for input zone detection.

i was just experimenting. Please tell me that are there any specific pins which are alloted for the lcd, buzzer? or i can use any of the pins?

and i have the same question for the pir motion sensor as well.

Some pins have specific uses. Digital pins 0 and 1 are used for the hardware serial port. They should not be used for other purposes.

There are specific pins for PWM. If you need PWM output, you should use those pins.

Other than than, you can use any pin for any device.

i was just going through the manual on the website. i am a bit confused. can i delete some program from the memory of the chip? and once i have uploaded the program do i have to lock the atmega chip using burn bootloader?

You can only have 1 program on the chip at a time. Uploading a new one overwrites the old one.

No need to lock or burn anything.