How To Perform Loop Back Test On Xbee Connected With Arduino- (Part 30/49)

Two Xbee S1 series transceivers modules are used in this project and the image of the same module shown in the following figure. Since the pitch of the pins of the modules are not breadboard compatible one can use the Xbee based design boards which comes with breadboard compatible pins.       

                                                               Fig. 2: Xbee S1 Series Transceiver Module                                                                                                      

The Xbee modules have several digital and analog I/O pins apart from these pins and the pin out of an Xbee module is shown in the following table:

Fig. 3: Pin Out Of Xbee Module

The Arduino board used in this project is the Arduino pro-mini board and the IDE version of the Arduino is 1.0.3 for windows. The image of the Arduino pro-mini board and the Arduino IDE are shown below:

Fig. 4: Typical Arduino Pro-Mini Board

Fig. 5: Arduino IDE Software Window

Since the arduino pro-mini board has no circuitary for interfacing it with the serial port or the USB port of the PC, an external USB to TTL converter board is required to connect it with the PC. This hardware helps in programming the Arduino board and also helps in the serial communication with the USB port of the PC.

Fig. 6: External USB to TTL converter board for programming Arduino and serial communication

Since the Xbee modules communicate using serial communication protocol with the interfacing devices they can be connected to a microcontroller using a minimum of four pins, Power supply, and Ground, UART Data Out, and UART Data In pins.

The pin number 2, UART Data Out is connected to the RX1 pin of the Arduino pro mini board and pin number 3 UART Data In is connected to the TX0 pin. The code written for this project communicates with the Xbee using the serial communication functions provided by the Arduino library. The functions like Serial.begin() which helps to initialize the serial port with a given baud rate, Serial.write() to send a data to the serial port, Serial.available() and Serial.read() functions to read data from the serial port are used in this project and they are already discussed in previous projects on how to do serial communication with the Arduino, how to send and receive serial data using arduino and how to do serial debugging with the Arduino.

In this project both the Xbee modules has to perform transmission and reception to complete the transmission of a data byte from PC to the Arduino board and back to the PC again. The block diagram below represents the implementation of the entire system.

Fig. 7: Block Diagram Of Loop Back Test On Xbee Connected With Arduino

THE CODE

The loop back testing code makes use of the above mentioned serial communication functions to communicate with the Xbee module. The Arduino board waits till it receives some data from the Xbee module which is connected to the PC through the Xbee connected to it and sends back the same data to the other Xbee module which is connected to the PC. Serial monitoring software is running in the PC side which can monitor and access the serial port where the Xbee is connected so that one can observe the incoming data and also send some data to the serial port where the Xbee is connected. The following text shows how the code will look like;

if(Serial.available())                                                      // wait till a data byte is received

{

    inByte = Serial.read();                                             // get incoming byte:

    Serial.write(inByte);                                                  // send the same character back to serial port

}

When the coding is finished one can verify and upload the code to the Arduino board as explained in the project how to get started with the Arduino. As soon as the board is powered up the Xbee in the Arduino board automatically establishes communication with another Xbee which is connected to the serial port of a PC. The second Xbee board can be connected to the PC using the same USB to TTL converter board which has been used to program the Arduino board. Now open the serial monitor software and type some text using the keyboard without turning on the ‘local echo’ option and one can observe the same characters appears on the serial monitor window.

Project Source Code

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/*============================ EG LABS ===================================//


 Demonstration on how to perform loop back test on XBEE with an arduino board


 The circuit:

 LCD:

 * LCD RS pin to digital pin 12

 * LCD Enable pin to digital pin 11

 * LCD D4 pin to digital pin 7

 * LCD D5 pin to digital pin 6

 * LCD D6 pin to digital pin 5

 * LCD D7 pin to digital pin 4

 * LCD R/W pin to ground

 * 10K resistor:

 * ends to +5V and ground

 * wiper to LCD pin 3

 * LED anode attached to digital output 9

 * LED cathode attached to ground through a 1K resistor


 XBEE:

 RX PIN OF XBEE TO TX0 PIN OF ARDUINO

 SHORT THE GROUND PINS OF ARDUINO AND XBEE


============================== EG LABS ===================================*/


#include <LiquidCrystal.h>


// initialize the library with the numbers of the interface pins

LiquidCrystal lcd(12, 11, 7, 6, 5, 4);


// give the pin a name:

int led = 9;

// incoming serial byte

int inByte = 0;         


void setup()

{

  // set up the lcd's number of columns and rows: 

  lcd.begin(16, 2);

  lcd.print("ENGINEERS GARAGE");

  lcd.setCursor(0, 1);

  lcd.print("   XBEE + GPS   ");

  

  // initialize the led pin as an output.

  pinMode(led, OUTPUT);  

  // start serial port at 9600 bps

  Serial.begin(9600);

  // wait for a while till the serial port is ready

  delay(100);


// send the initial data once //    

  Serial.print('n');

  Serial.print("      EG LABS   ");

  Serial.print('n');

  Serial.print('r');

  Serial.print(" XBEE LOOP BACK TEST");

  Serial.print('n');

  Serial.print('r');

  Serial.print('n');

}


void loop()

{

  // if we get a valid byte, read analog ins:

  if(Serial.available())

  {

    // get incoming byte:

    inByte = Serial.read();          

    // send the same character back to serial port

     Serial.write(inByte); 

    // blink the LED once //    

    digitalWrite(led, HIGH);       

    delay(100);     

  }

  else

    digitalWrite(led, LOW);   

}

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Circuit Diagrams

Circuit-Diagram-Interfacing-XBEE-Arduino

Project Components

Project Video

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Filed Under: Arduino
Tagged With: Arduino, xbee, zigbee
 

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