Interface RF Module

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Interface RF Module with ArduinoPosted on December 10, 2012b y torongooo2

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What is RF module? An RF Module (Radio Frequency Module) is a small electronic circuit used to transmit and/orreceive radio signals on one of a number of carrier frequencies. RF Modules are widely used inelectronic design owing to the difficulty of designing radio circuitry. RF Modules are most oftenused in medium and low volume products for consumer applications such as garage door

openers, wireless alarm systems, industrial remote controls, smart sensor applications, andwireless home automation systems.The operating frequency of RF module can be varied. But we offer two kinds of, one of them is433 MHz and another is 315 MHZ. The transmission occurs at the rate of 600bps 10Kbps.Thetransmitted data is received by an RF receiver operating at the same frequency as that of thetransmitter.

Specification Frequency: 433 MHz Modulation: ASK Receiver Data Output: High 1/2 VCC, Low 0.7v

Transmitter Input Voltage: 3-12V (high voltage = more transmitting power). Receiver Input Voltage : 3.3-6V (high voltage = more receiving power) For total specification you can visit this link: Address

Pin Diagram

Rx module Pin description:

Pin No Function Name

1 Ground(0V) Ground
http://emguide.wordpress.com/2012/12/10/15/http://emguide.wordpress.com/2012/12/10/15/http://emguide.wordpress.com/author/torongooo2/http://www.seeedstudio.com/wiki/index.php?title=433Mhz_RF_link_kithttp://www.seeedstudio.com/wiki/index.php?title=433Mhz_RF_link_kithttp://emguide.wordpress.com/2012/12/10/15/pindiagram/http://www.seeedstudio.com/wiki/index.php?title=433Mhz_RF_link_kithttp://emguide.wordpress.com/author/torongooo2/http://emguide.wordpress.com/2012/12/10/15/http://emguide.wordpress.com/2012/12/10/15/


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2-3 Serial data output pin Input

4 Supply voltage(3.3V-6V) Vcc

5 Antenna Ant

Tx Module Pin description:

Pin No Function Name

1 Antenna ANT

2 Serial data input pin Output

3 Ground(0V) Ground

4 Supply voltage(3V-12V) Vcc

Arduino Compatibility with RF module Now we are coming to our main point. The question, is how can we connect a Arduino with RF

module?What would be the circuit diagram? You dont need to be worried. Here I have presented a tutorial so that you can easily understand what you need to do .Its so simple toconnect your Arduino with RF module. We have already developed Transmitter and Receivershields which are fully compatible with Arduino board. Just plug and play, nothing else. So itwould be very easy for you to connect a Transmitter or Receiver shield with Arduino and workwith it. In our shield we also provide a connector system so that you can also connect other Tx orRx modules to this shield. So it is a wide open door for everyone who really wants to work withRF.

Working procedure First you need to connect your Transmitter shield with an Arduino board and also a Receiver

shield with another Arduino Board. Plug 12V Dc with both of the Arduino Boards so that Arduino can start working. If you think, you dont want to use our Rx, Tx module then you need to connect wire

properly between Tx, Rx module and also shield. You dont need to be wor ried about this.By shield you also can connect other Tx, Rx module with Arduino. For Schematic pleasecheck the link:

Now your circuit setup is complete. For coding you need to plug Usb cable with your Arduino.


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Now start your code and debug. Enjoy!!!Coding technique:

I believe that you know something about Arduino coding. Now I start the coding technique forTx and Rx module. To send data you need to synchronize your Tx and Rx module . For thisyou need to send 0b01010101 or U which has a binary value 01010101. This is called pre-

amble . This pre-amble byte is usually sent 2 to 5 times in a row to synchronize sender andreceiver , BUT NOT ALWAYS! Once you have synchronized your chip to the RF receiver youcan sample the bits in the middle of your data line. In your data you also need to attach starting

bit and ending bit, without these two bits you cant understand when the main data is started andwhen finished. Data pattern can be like this: UUU/PiLabs,Rock#@ . In this data pattern youcan notice that at first I have sent U 3 times for synchronization and after that I have put thestart bit by / and then sent data which is PiLabs,Rock and finally sending finish bit by#@ . Here I will attach the full code for receiver and transmitter also . In my code I use someArduinos special function which is: findUntil readBytesUntil

For details about these two functions you need to click here, findUntil and readBytesUntil . ForArduinos function you need to visit this link Libaries . To complete the project you need to senddata according to my data pattern and then receive it by another Arduino. Here I have attachedmy code and also library which is shown below. You can easily debug your code by Arduinosserial port. In my code you can find a scan() function which I have built for scanning data from / to #@. Yo u can easily use it in your code also. This scan() function would be very helpful.By using this function you can sort out your main data.

Schematic of Receiver module

In schematic you can find Arduino board which is U1, RF receiver connector which is mentionas RF RECEIVER. Here I have connected two relays for other works. Suppose you want to

control two electrical loads by RF transmitter (Ex: RF Remote control). Here you can notice thatD9 & D10 are mentioned as Relay1 and Relay2. By these two pins you can control the relays.The main theme is you get data from RF receiver then you need to check it with your predefineddata. If it matches, then you can do anything you want.

Code for Receiver module
http://arduino.cc/en/Reference/StreamFindUntilhttp://arduino.cc/en/Reference/StreamFindUntilhttp://arduino.cc/en/Reference/StreamFindUntilhttp://arduino.cc/en/Reference/StreamReadBytesUntilhttp://arduino.cc/en/Reference/StreamReadBytesUntilhttp://arduino.cc/en/Reference/StreamReadBytesUntilhttp://arduino.cc/en/Reference/Librarieshttp://arduino.cc/en/Reference/Librarieshttp://arduino.cc/en/Reference/Librarieshttp://emguide.wordpress.com/2012/12/10/15/reveiver/http://arduino.cc/en/Reference/Librarieshttp://arduino.cc/en/Reference/StreamReadBytesUntilhttp://arduino.cc/en/Reference/StreamFindUntil


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#include // Include Software Serial libary

SoftwareSerial mySerial(4,6); // Rx,Tx

//===========Scan function=================================

void scan()

{

//=================Variable Initialization================//

char tmp[20];

char data[20];

for(int i=0;i


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tmp[i]=0;

}

byte len=0;

//========================================================//

//===============Algorithm Start=========================//

if(mySerial.available()) // If Software Serial detect any data in it's buffer

{

mySerial.setTimeout(10000);// Set timeout for 10 sec

mySerial.flush(); // Flush MySerial buffer

// This is build in function of Software serial


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// findUntil() reads data from the stream until the target string

// of given length or terminator string is found.

// The function returns true if target string is found, false if timed out

// Syntax: stream.findUntil(target, terminal)

// Sending Data pattern would be in this example: UUU/PiLabs*@

// Sending Data pattern must be: /USER DEFGINED DATA*@

if(mySerial.findUntil("@","@"))//checking the condition

{

// readBytesUntil() read characters from a stream into a buffer. The function

// terminates if the terminator character is detected, the determined length has


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// or it times out.

// readBytesUntil() returns the number of characters placed in the buffer. A 0 me

// Syntax: stream.readBytesUntil(character, buffer, length)

len= mySerial.readBytesUntil('@',tmp,50);// From this instruction we can get leng

// Also saved the string in tmp

Serial.println(tmp); // For Debugging we print tmp string in s

Serial.println(len); // For debugging we print the length of s

int i=0; // Initialize variable i

for(i=0;i


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data[i]=0;

}

// ===Algorithm for Sorting main data from Total String======

while(tmp[i]!='*') // Searching for * Because Main data star

{

i++; // Increamented index by 1

}

i++; // When * is found index increase 1 bcoz

// after *

int j=0; // Initialize j by 0


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while(tmp[i]!='/') // Now its searching for '/' And till '/'

{

data[j]=tmp[i]; // Stored data in data variable from string

i++; // Increament index

j++; // Increament index

}

Serial.println(data); // Serial data print in serial terminal

// strcmp is a function which return 0 when two string match

if(strcmp("PiLabs,Rock",data)==0)

{ // And in here it checked by strcmp function

Serial.println("GOTCHA"); // Serial Printout


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}

}

}

}

//================Setup function=============================================

void setup()

{

Serial.begin(9600); // Serial Port initialization by 9600 Bps

mySerial.begin(1200);//SoftwareSerial port initialization by 1200 bps

mySerial.setTimeout(10000); // Set time out 10 sec


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mySerial.flush(); // Software serial buffer flush

}

//=================loop Function====================================

void loop()

{

scan(); // Called scan function

}

Schematic of Transmitter Module
http://emguide.wordpress.com/2012/12/10/15/transmitter/


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In schematic you can find Arduino Board, which is denoted by U1. You can see some buttons atthe right side of the Schematic. This button is used for general purpose. In this RF shield we havetried to give you some kind of gaming flavor. But the question is, how?? There are 5 switches,you can use it like up, down, left, right and enter. And according to these buttons you need tosend data through Tx module. Here Tx module connector is denoted by TX. At the upper left

side of the schematic you can notice that we have put a seven segment display which isCC(Common Cathode)type. When a switch is pressed,the corresponding switch number(1,2,3,4,5) will be shown in seven segment display. For controlling seven segment displays wehave used 7447 BCD to Seven segment drivers IC. For 7447 datasheet you can click thislink. Datasheet of 7447 .

Code for Transmitter module

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#include // Include Software Serial libary

SoftwareSerial mySerial(6,7); // Rx,Tx

//=======================================================

//============show__segment function =========================

//=======================================================

void show__segment(int button__no)// Show__segment function start

{

if(button__no==0)// if button no 0 is pressed
http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=10&sqi=2&ved=0CGYQFjAJ&url=http%3A%2F%2Fwww.eng.uwo.ca%2Fpeople%2Fkmcisaac%2FCoursepages%2FECE339a%2FDatasheets%2F7447.pdf&ei=5VDAUNPiKIOE2gXexIGYDA&usg=AFQjCNFwZLkgdAwJ7htnhpFxkXh9v8YR5Ahttp://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=10&sqi=2&ved=0CGYQFjAJ&url=http%3A%2F%2Fwww.eng.uwo.ca%2Fpeople%2Fkmcisaac%2FCoursepages%2FECE339a%2FDatasheets%2F7447.pdf&ei=5VDAUNPiKIOE2gXexIGYDA&usg=AFQjCNFwZLkgdAwJ7htnhpFxkXh9v8YR5Ahttp://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=10&sqi=2&ved=0CGYQFjAJ&url=http%3A%2F%2Fwww.eng.uwo.ca%2Fpeople%2Fkmcisaac%2FCoursepages%2FECE339a%2FDatasheets%2F7447.pdf&ei=5VDAUNPiKIOE2gXexIGYDA&usg=AFQjCNFwZLkgdAwJ7htnhpFxkXh9v8YR5Ahttp://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=10&sqi=2&ved=0CGYQFjAJ&url=http%3A%2F%2Fwww.eng.uwo.ca%2Fpeople%2Fkmcisaac%2FCoursepages%2FECE339a%2FDatasheets%2F7447.pdf&ei=5VDAUNPiKIOE2gXexIGYDA&usg=AFQjCNFwZLkgdAwJ7htnhpFxkXh9v8YR5A


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{

digitalWrite(2,LOW);// 0|


digitalWrite(4,LOW);// 0|so no is 0


mySerial.println("UUU/PiLabsON0*@");// Data send via mySerial

}

else if(button__no==1) //if button no 1 is pressed

{

digitalWrite(2,HIGH);// 1|


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}

else if(button__no==2)//if button no 2 is pressed

{


digitalWrite(3,HIGH);// 1|



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}


{

digitalWrite(2,HIGH);// 1

digitalWrite(3,HIGH);// 1

digitalWrite(4,LOW);// 0 So no is 3

digitalWrite(5,LOW);// 0



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}


{



digitalWrite(4,HIGH);// 1|so no is 4



}

}


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//=======================================================

//=============== Scan__button function =======================

//=======================================================

void scan__button()// Scan__button function start

{

if(digitalRead(12)== LOW)// Checking 12 no pin for button press

{

show__segment(1); // show__segment function call for no:1

}

else if(digitalRead(10)== LOW)// Checking 10 no pin for button press


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{

show__segment(2);// show__segment function call for no:2

}


{

show__segment(3);// show__segment function call for no:3

}


{

show__segment(4); // show__segment function call for no:4


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}

}

//=========================================================

//=================== Setup==================================

//============================================================

void setup()

{

pinMode(2,OUTPUT);//Define output, this pin is for A of 7447

pinMode(3,OUTPUT);//Define output, this pin is for B of 7447

pinMode(4,OUTPUT);//Define output, this pin is for C of 7447


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pinMode(5,OUTPUT);//Define output, this pin is for D of 7447

pinMode(8,INPUT);//Define input

digitalWrite(8, HIGH);// Pull Up enable


digitalWrite(9, HIGH);//Pull Up enable







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Serial.begin(9600); // Serial Port initialization by 9600

mySerial.begin(1200); // Software Serial port initialization

mySerial.setTimeout(10000); // Set time out 10 sec

mySerial.flush(); // Software serial buffer flush

show__segment(0); // By default it shows 0

}

//========================================================

//==================== loop=================================

//========================================================


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void loop()

{

scan__button();// scan__button function call

}

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Interface RF Module

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