How to read info from an Xbee Pro S2B to an Arduino with a Xbee Pro S2B

Question

I am using two XBee Pro S2B modules. One (Router) connected to the laptop via a UART cable. The other (Coordinator) connected to an Arduino Mega with the sketch below. All I need it to do is turn a LED on and off and display the status in the IDE serial monitor. I am using Arduino IDE (v1.6.0).

Arduino sketch:

#include <SoftwareSerial.h>

SoftwareSerial xbee (2,3);

int myData = 0;
int ledPin = 13;

void setup()
{
    Serial.begin(9600);
    xbee.begin(Serial);

    pinMode(ledPin, OUTPUT);
}

void loop()
{
    if (Serial.available())
    {
         int myData = Serial.read();

         if(myData == '1')
         {
             digitalWrite(ledPin,HIGH);
             Serial.write(myData, DEC);
         }
         if(myData == '2')
         {
             digitalWrite(ledPin,LOW);
             Serial.write(myData, DEC);
         }
     }
 }

Where did I go wrong?

Answer 1

You have two serial connections. One for the main USB of the board and one for the XBee.

So you need to read from the XBee and write to the serial USB?

I don't know what speed you have configured for your XBee so I have set it to 9600.

This example reads from the XBee and writes to the Serial/USB port

#include <SoftwareSerial.h>

SoftwareSerial xbee (2,3);

int myData = 0;
int ledPin = 13;

void setup()
{
    Serial.begin(9600);
    xbee.begin(9600);

    pinMode(ledPin, OUTPUT);
}

void loop()
{
    if (xbee.available())
    {

         int myData = xbee.read();

         Serial.print("Data has arrived on the Arduino");
         Serial.write(myData);
         Serial.println();

         if(myData == '1')
         {
             digitalWrite(ledPin,HIGH);
             Serial.write(myData);
         }
         if(myData == '2')
         {
             digitalWrite(ledPin,LOW);
             Serial.write(myData);
         }
     }
 }

Note: Your example also used Serial.write() with the wrong argument DEC which applies to Serial.print(). X-CTU and Arduino both send ascii which is also what the Serial.print() does. However the Serial.read() just reads the byte so we need to use Serial.write() to send the same bytes back to the other end.

You can also make life a bit easier by replacing xbee.available() with Serial.available(). Then use the Arduino IDE serial monitor to both send and receive. This means that you just use the one USB connection to prove the code.