what im trying to do is have 1 board control 4 or more doors. is it possible or do i need a board set up for each door? i know i will need a rfid at each door. i also know theres some issues with the signal distance but they make a usb model that could work since i wouldnt have the loss. i would want the door that i scan only to open, not all doors.
Depending your your RFID reader, one Arduino should have sufficient I/O capacity to control 4 locks and connect to 4 readers.
For example, this reader provides a serial output and would only need 1 input pin on the Arduino to read it. Controlling a door lock should only take 1 digital output pin. This would total 8 pins on your Arduino (less then available), but would require software serial for the Arduino UNO. The performance capabilities should be fine for the Arduino for this purpose, the biggest issue would be the additional hardware you would need to extend your signals from your Arduino to the RFID pads and to the locks.
any idea on the code and how to wire it all up? im new to all this but i have seen walk throughs on 1 door reader and lock.
any idea on the code and how to wire it all up?
See this
Open access RFID control
https://code.google.com/p/open-access-control/