[SOLVED] Trouble connecting Arduino to DFRobot APC220

Hello all,

I am trying to set up wireless communication between two Arduinos via DFRobot APC220 radio modules. The simplest thing I want to see is: I press a button on one Arduino, the other one flashes the LED. Here is my setup:


Code for Arduino 1 (the transmitting one):

Code: Select allint ledPin = 13; int myPin = 3; int prev=LOW; void setup() {                  pinMode(ledPin, OUTPUT);   pinMode(myPin,INPUT);   Serial.begin(9600); } void loop() {     int a=digitalRead(myPin);   if( a==HIGH && prev==LOW ){     digitalWrite(ledPin,HIGH);     // short flash to confirm button press     delay(100);     digitalWrite(ledPin,LOW);     Serial.write(50);            // send one byte   }   prev=a;     delay(100); }

Code for Arduino 2 (the receiving one):

Code: Select allint ledPin = 13; void setup() {                  pinMode(ledPin, OUTPUT);   Serial.begin(9600); } void loop() {} void serialEvent(){   int b=Serial.read();   if(b>=0){     if(b==50){       digitalWrite(ledPin,HIGH);        // long flash to confirm correct reception       delay(500);       digitalWrite(ledPin,LOW);     }else{       for(int i=0;i<3;i++){             // three short flashes to indicate error         digitalWrite(ledPin,HIGH);         delay(100);         digitalWrite(ledPin,LOW);         delay(100);       }     }   } }

It doesn't work.   I press the button, the first Arduino flashes, the second Arduino does nothing. I tried connecting them by wires: GND to GND and TX to RX, this way it works, but wirelessly it doesn't.
 

How can I find out where is the problem? Does the first APC220 understand my signals, does it transmit anything, does the second one receive something from the air?Are both APC220 devices ready to work upon applying power to them?Do I just need to send bytes to Serial and they will come out on the other side? Or should I use AT commands or something?I did not connect the EN pin, but it is "high" by default, so the device should be always on.The default baud rate of APC220 is 9600, so I am starting Serial with this value.On my APC220, pin 6 is marked AUX. In one datasheet, pin 6 is described as "MUX - expanded for other functions"; in another datasheet and in the wiki, it is "AUX - Receive (low) Transmit (high)". Should I use this pin? I tried to connect it to VCC on the transmit side - still no luck.I connected both APC220 to computer and set them up via RF-Magic. I have set them to the same frequency, keeping all other parameters unchanged. There are some mysterious settings like "parity" and "stop bits". Should I worry about them from the Arduino side?

Am I missing something obvious?