Talking to an Arduino from PHP I was able to talk to my Arduino without using an Ethernet or a wireless shield. Best part is that I only have 4 lines in my PHP script :) Things you need to have : Arduino board with a USB Cable Breadboard 1 LED Few jumper wires 220 OHM resistor Additionally Arduino IDE, PHP, Apache2 installed Linux box :) 1. Connect Arduinos GND pin to breadboards ground line. 2. Connect Digital pin 13 to breadboards + line. 3. Connect LEDs Anode(long leg) with the breadboards + line using the 200 OHM resistor. 4. Connect LEDs cathode(short leg) with breadboards - line directly using a jumper cable. You are done with the circuit prototype, Now connect the Arduino board to your PC. Open Arduino IDE, click on tools> Serial port. You can see the device connected to a port similar to "/dev/ttyACM0". Lets write our PHP snippet, <?php $comPort = "/dev/ttyACM0"; /*Update to the correct port */ $fp =fopen($comPort, "w"); fwrite($fp, ...