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This video shows a very basic setup of two arduinos talking wireless over RF.

The two rf-boards used in this setup were discussed earlier in this post.

The left arduino has a sensorshield with a PIR-sensor and a rf-transmitter connected to it. When the PIR-sensor detects changes in IR-radition in it’s field of view, it triggers the rf-transmitter and a red led.

The right arduino just has a rf-receiver and a green led connected to it. When the right arduino receives a radio signal the green led turns on.

Code for the transmitting arduino:

int ledPin = 12;                 // pin
int pirPin = 4;                  // pin for PIR-sensor
int RFoutPin = 7;                // pin for RF transmitter
int value = 0;                   // used to store data from PIR-sensor

void setup() {
pinMode(RFoutPin, OUTPUT);       // declare RF-transmitter as output
  pinMode(ledPin, OUTPUT);       // declare led as output
pinMode(pirPin, INPUT);          // declare PIR-sensor as input
}

void loop() {
value = digitalRead(pirPin);     // read PIR-sensor
if (HIGH == value) {             // transmit HIGH signal
digitalWrite(RFoutPin, HIGH);
digitalWrite(ledPin, HIGH);
}
else {                           // transmit LOW signal
    digitalWrite(RFoutPin, LOW);
    digitalWrite(ledPin, LOW);
 }

}

Code for the receiving side:

int ledPin = 11;                  // pin for the LED
int RFinPin = 7;                  // pin for the RF receiver
int val = 0;                      // variable for reading the pin status
void setup() {
pinMode(ledPin, OUTPUT);          // declare LED as output
pinMode(RFinPin, INPUT);          // declare RF receiver as input
}
void loop(){
 val = digitalRead(RFinPin);      // read input value
 if (val == HIGH) {               // check if the input is HIGH
    digitalWrite(ledPin, HIGH);   // turn LED ON
 } else {
  digitalWrite(ledPin, LOW);      // turn LED OFF
  }
}

Ok, maybe this example was a bit too easy.

Check part 2 to learn how to connect arduino to a network and send/receive data to/from a webpage using the ethernet shield discussed here.

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