Arduino ZigBee Wireless Status Link

Using a pair of Arduino Uno boards with XBEE ZigBee shields, we need to continuously illuminate four LEDs on a receiver reflecting four digital inputs on the transmitter. When a digital input on the transmitter goes high, the corresponding output on the receiver must turn on in less than 1/2 second. When a digital input on the transmitter goes low, the corresponding output on the receiver must turn off in less than 1/2 second.