433MHz vehicle unlocking with Arduino / Atmel AVR

Having only one key fob for the van is anxiety-inducing in case it fails, so I decided to build a replacement with an Arduino/ATMega and a 433Mhz transceiver module.

Resources:

• 433Utils library by ninjablocks
• Alternative rc-switch library

This was originally for a YouTube video which you can watch at https://www.youtube.com/watch?v=ANQsj8KCzRc.

Code:

sniffer.c

#include

RCSwitch mySwitch = RCSwitch();

void setup() {
	Serial.begin(9600);
	mySwitch.enableReceive(0); // Receiver on inerrupt 0 => that is pin #2
}

void loop() {

	if (mySwitch.available()) {
		int value = mySwitch.getReceivedValue();
			if (value == 0) {
				Serial.print("Unknown encoding");
			} else {
				Serial.print("Received ");
				Serial.print( mySwitch.getReceivedValue() );
				Serial.print(" / ");
				Serial.print( mySwitch.getReceivedBitlength() );
				Serial.print("bit ");
				Serial.print("Protocol: ");
				Serial.println( mySwitch.getReceivedProtocol() );
			}
		mySwitch.resetAvailable();
 
	}
}

transmitter.c

#include <RCSwitch.h>

#define CODE_one 10692289
#define CODE_two 10692290
#define CODE_three 10692296
 
const int buttonPin = 4;
const int ledPin =  13;
int buttonPushCounter = 0;
int buttonState = 0;
int lastButtonState = 0;

RCSwitch mySwitch = RCSwitch();
 
void setup() {
	pinMode(ledPin, OUTPUT);
	pinMode(buttonPin, INPUT);
	pinMode(7, OUTPUT);
	Serial.begin(9600);
	mySwitch.enableTransmit(7);
}

void loop() {
        buttonState = digitalRead(buttonPin);  
        if (buttonState != lastButtonState) {
          if (buttonState == HIGH) {
            buttonPushCounter++;
          }
          lastButtonState = buttonState;
           if (buttonPushCounter % 2 == 0) {
            digitalWrite(ledPin, LOW);
            mySwitch.send(CODE_one, 24);
            buttonPushCounter = 0;
          } else {
            digitalWrite(ledPin, HIGH);
            mySwitch.send(CODE_two, 24);
          }  
        }
     }