hii, i want to make a rfid based parking lot access...for this initially i'm asked to make a barcode scanner..the code is to be sent to the microcontroller nd den interfaced wid sensors...wat type of barcode scanner can help me wid this??? can microcontroller AT89C51 be interfaced wid dis scanner???

 

Used bar code scanners can be found cheaply on places like eBay or surplus stores, even places that sell POS terminals will probably have a lot of the older ones around. Find one and gut it.

RFID is going to be more difficult, a reader that can work at any sort of distance tends to be expensive.

There's a general rule about electronics - it's expensive when it's the new "in thing" then becomes bargain basement when it becomes obsolete as several of the older bar code scanners have. We had to upgrade all of ours because several of our customers started using some new code standard the older ones won't read.

 

If you are talking about the "Touch your badge to this pad to open the gate" type, radio shack USED to sell a paralax rfid kit with 2 rfid tags.

At least I think the tags came with it.

This can be used with a uC to operate relays to operate motors, actuators, lights, and all that good stuff.

We have a member on here, BMorse, If I remember correctly, has the kit.

Ill see if I can find the post.

Well that didn't take long:
http://forum.allaboutcircuits.com/showthread.php?t=36023

 

actually i'm asked to design d barcode scanner, so i cant buy one..can u plzz help me wid how i'm supposed to start wid it...

 

You'd be crazy to try to design a barcode scanner. No matter how much it costs, go out and buy one.

Actually, if it's someone else who is telling you to design the barcode scanner, they're the crazy one. This is an unreasonable use of a person's time.

 

Buy the guts from a surplus store and build a case around it.

Do you (or the person asking) even realize what all is involved in making one of these devices work?