BlueLink-Silver Bluetooth Modem

BlueLINK-Silver is an excellent Class 2 Bluetooth modem. It can be used to create desired personal area networks which includes your embedded project. The main advantage of such a network is that it offers very high level of security for data transmission. The modem supports wireless transmission of about 10 meters. Thus it is an excellent option for short range applications. The input voltage is strictly regulated by the voltage regulator in the module that is inbuilt. Also no extra level conversion is needed The 7 pin module has 4 important pins which are VCC, GND, TXD and RXD.

The Bluetooth modem could be easily powered by simple battery attachment. This module can be powered from 3.3V up to 6V for easy battery attachment. All signal pins on the remote unit are 3V-6V tolerant.It requires a maximum voltage of nearly 6V. RS232 to TTL or USB to TTL converters are very relevant for the connection of modem to your system.

These modems play a good role in establishing wireless communication between your system and the target circuitry. One could easily transfer data using Bluelink Silver with simple connections.

Features

•   FCC Approved Class 2 Bluetooth® Radio Modem
•   SPP (Serial Port Profile) support
•   Extremely small radio – 0.15×0.6×1.9″
•   Breadboard Compatible
•   Onboard Status,Connected and Power LED
•   Very robust link both in integrity and transmission distance (18m)
•   Hardy frequency hopping scheme – operates in harsh RF environments like WiFi, 802.11g, and Zigbee
•   Encrypted connection
•   Frequency: 2.4~2.524 GHz
•   Operating Voltage: 3.3V-6V
•   Serial communications: 2400-115200bps
•   Operating Temperature: -40 ~ +70C
•   Built-in antenna
•   Dimensions: 51.5×15.8×5.6mm
Specification
Pin Diagram

Pin Detail

Layout

How to Test?

1.Bluetooth configuring of BLueLink(SILVER) via PC:

The BLueLink SILVER is one of the efficient Bluetooth TTL modules from Roving Networks. BLueLink SILVER is RN42 based .The speciality of Bluetooth modules from rhydoLABZ is that you can interface these with microcontrollers without any external hardware circuitry, let it be a controller with 3V3 logic level or a controller with 5v logic .You just need to give appropriate supply (3v3/5v) to the module.

Before interfacing BLueLink directly with a controller using its serial port, it would be better to first learn how the module actually works!The easiest way is by connecting it with a PC and passing AT commands. The module works at logic level of 3v3 or 5v , so in order to interface BLueLink with the system you should make use of a converter ,probably a USB to TTL (3v3/5v) converter or an RS232 to TTL converter. More preferable option will be to use a USB converter since RS232 ports are little obsolete and are not available in modern desktop systems and laptops. Hence it would be better to choose a TTL converter with USB option.

It is preferable to use a FTDI Breakout(3v3) or FTDI Breakout(5V) from rhydoLABZ, let it be 3v3 or 5v whichever be, it would be suitable with the BLueLink module.This breakout basically acts as a converter and is very compact and easy to use.

When we have a look at BLueLink (SILVER), Six interfacing pins can be seen in the product namely CTS,RTS ,RX ,TX ,VCC ,GND and RST. VCC and GND form the supply for the module. Through the RST pin we can Reset the module if required.RX and TX pins are the serial communication pins available in the module for serially communicating in UART.CTS & RTS are the pins made available for Hardware flow control which we shall see later in this thread.

Make connections from the BLueLink module to the FTDI breakout as shown below:

Connect TX(module) to RX of FTDI Breakout and similarly RX(module) to TX of FTDI breakout and you can obviously give supply to the BLueLink module from the breakout by simply connecting VCC (breakout) to VCC(module) and make GND common. You can have a bunch of jumper wires to make suitable connections.After that interface the FTDI breakout with a PC using a USB miniB cable. Information regarding installing FTDI breakout in your PC can be found here.When you reach this point all your hardware connections are complete. Now you can proceed with configuring the Bluetooth module by using a PC.

When you first connect your breakout you can view the COM port to which the breakout got selected in your PC in the Device Manager. For Example you can see the image below:

When connected the module you can see it got connected to COM38 as we can clearly observe in the above picture.
Now in order to communicate with module there is a terminal software like Realterm which provides systematic user interface options to communicate with any device via PC’s COMport. Hyperterminal will also work but Realterm is Recommended.

Using REALTERM

When you have connected the module to the FTDI breakout which in turn has been connected to the system, you can see a blue LED that glows constantly and remains stable when the module has been powered up, it is shown by the name PWR.
The status LED (Green) blinks continually with pauses ,which represents the mode in which the module is in.
When you have first powered up then this status LED blinks Two times a second indicating that it is in Startup/Config timer Mode. After the configuration timer has elapsed it comes to IDLE mode in which the status LED blinks once in a Second. This state is also used by the module to represent that the module is discoverable or is inquiring.
Now open realterm and follow the steps below:

Select the ANSI option from display as you can observe from the above picture.Now, when the module comes to your hand it is by default configured at 115200 baud rate. So select the appropriate baud rate as you can give in the leftmost top Baud option.Keep all other settings as shown in the window like for parity and data bits…

After selecting the comport as 38 click on change.

Before exiting these options click Open. At this the port gets connected at 115200 baud rate to the FTDI breakout.Keep the hardware flow control also as none.Now click the Send option and you will be able to see the facilities described in the picture.

Inorder to test the connectivity of the module to the system we first send ‘$$$’ as shown in the picture, write it in that space provided and then click ‘Send ASCII ‘then the module enters Command mode and the status LED (green) starts blinking rapidly at the rate of 10times/s indicating that it has entered configuring mode.
Now whatever data you are trying to send to the module will be treated as commands and the module responds accordingly. All the commands whether it be data should be given at the same location where ‘$$$ ‘ was written or else you can click the window where CMD is written and start typing the characters directly there.
When you are finished you can return back to the earlier mode by giving command ‘—\r’ .’\r’ or the carriage return is a must as without it the module shall not respond to the command. Apart from ‘$$$’ all commands should be preceded with \r. Now you can proceed with rest of the commands as described in the datasheet….
For Example:You can view the current configuration of the BLueLink module by giving command ‘D\r’Then the reply will be like ,as shown in the picture below:

In the beginning you can see ‘END‘ which is actually the result of a previous ‘—\r’ command and then after that ‘$$$’ was again given to Enter the command mode at which the modem replied with’ CMD‘.
Now we gave the command ‘D\r’ and modem replied with all its basic settings .We can observe that the BLueLink Module is by default in slave mode which means that it can be paired from an external Bluetooth device or a master and can be connected to it.

Now we have reached a situation in which we can search this module from other Bluetooth devices, Although the BLueLink is configured as slave we can also initiate a Bluetooth connection from it, and obviously it can also be discovered and connected from other Bluetooth devices in SPP profile.The serial port profile behaves as a wireless serial link, the data bytes that we send from a Bluetooth device are received at the other end like if we have connected a serial cable in between them.
The simplest way to begin is a USB Bluetooth dongle. You can connect it to your PC and make Bluetooth connectivity available. Here are some steps by which you can search for the BLueLink module which we already powered using the FTDI breakout described earlier.

First install the Bluesoleil software and Bluetooth dongle in your system.
Then open it you can see a window like this:

When you press the red button in the middle then the software displays status as ‘Searching for devices..’You can also do this by going to the view option and then by clicking Refresh services.
After the search is complete you can see our RN-42 based BLueLink module has been found out by Bluesoleil:

When it gets detected simply right click and give refresh services as shown above. At this you will be able to view the status like shown below:

After that you can right click the RN42 icon and click connect, if the module is not already paired it may ask a passcode and at this you can give the default set passcode as 1234 and then press OK.

Once connected you will be shown the above window and the BLueLink SILVER module will have its CNT led(yellow) turned on when connected. Now see status by right clicking..

You can observe the COM port to which the SPP connection from Bluesoleil got connected.Select the very same Comport(COM4 ) in the terminal window that you wish to use in order to communicate with BLueLink.
BLueLink SILVER was connected to COM38 which we already know.Now what we have to do in order to test our Bluetooth connection?We will open a terminal with COM4 selected, in this, baud rate is not important as the communication is from the dongle.
And another terminal will be opened in which COM38 will be selected which we saw earlier, in this case giving appropriate baud rate is significant ,in our case it will be 115200 baud ,with other settings like parity none, data bits 8,stop bit 1 and hardware flow control also none .
Let us see some images relating to the data transfer.

It would be better to use realterm for one COM and HyperTerminal for the other one because sometimes two realterms may not work correctly, Or else you can first try with realterms itself,If you are finding problems in opening a new realterm with one realterm already opened then you can switch to HyperTerminal.

Whatever data we type in one terminal will be reflected in the other one .
You can also do by connecting the Bluetooth dongle to any other system and then initiating Connection from there.

Using hardware flow control in BLueLink :

Now if you make the CTS pin high during data transmission then the BLueLink module will not send any further data till it is cleared. So in this way you can buffer in the incoming data to the BLueLink over the Wireless link. This is the case when you don’t want the module to send data.
Usually RTS pin always remains low, it becomes high when it wants us not to send any more data, if its high then whatever data we send to BLueLink will not get transmitted over the wireless SPP link.
Such a situation rarely happens only in the case when we are using the module for high-end applications and you are sending a very large amount of data chunks over the wireless link. So when module again clears RTS pin we can send data to the module.

Initialising Bluetooth connection using BLueLink SILVER

Till Now we were treating BLueLink as slave. When we configure it as master then the module cannot be discovered or connected from other Bluetooth devices ,it can only initiate one. In slave mode the module is connectable and discoverable that is how we were able to discover and connect the module from the Bluesoleil software but we can also make outbound connections from the module even when it is in slave mode this makes it unique when compared with other Bluetooth modules and the older version of BLueLink itself.
As now you have become familiar with Realterm so you can proceed with below steps:
To search a Bluetooth device when in slave mode simply give:
$$$
The module responses back with
CMD
Then start an inquiry session,give:
I\r and then press send ASCII.It shall reply with inquiry,COD=0.After sometime the number of Bluetooth devices that have been
found in the vicinity will be replied from the module with “found <number>”. Along with it we will be receiving the Bluetooth device’s address in the format may be after a little delay :
<Bluetooth address>,<Bluetooth device name>,<Device Class>
Store this remote address just found by giving command:
SR,<Bluetooth Address>\r
Module Replies with AOK
Now to initiate connection give C\r.
It replies TRYING
On connection you may not see any indication in your terminal the status of connection can be known by the CNT LED(yellow) on the module.
For more details regarding commands you can refer the AT command set and datasheets from here.

2.Testing BlueLINK-SILVER with Arduino

Bluelink SILVER Bluetooth module can be interfaced easily with Arduino board. Here we have used the board : Arduino Duemilanove for checking the Bluelink SILVER Bluetooth Module. The connection diagram is shown below:

Bluelink-Arduino connection

Following is the sample code to show communication of Bluelink SILVER Bluetooth module with Arduino:

/****************************************************************************************
 The following program turns the LED( 13th pin of Arduino board)  ON when letter 'O' or 
 'o' is pressed and turns OFF the same LED when 'F' or 'f' is pressed (slave mode) .
 BOARD   : Arduino Duemilanove
****************************************************************************************/

#include<string.h>
char string[30];
boolean sendata=false;

void setup()
{
 Serial.begin(115200);
 pinMode(12,OUTPUT);//reset
 pinMode(13,OUTPUT);//Onboard LED status
 digitalWrite(12,LOW);
 delay(20);
 digitalWrite(12,HIGH);
 delay(1000);
 Serial.print("$$$");
}
void loop()
{ 
   static int i=0;
   static char x;

  if(Serial.available()>0)
 { 
     x=Serial.read();
     if(x!='\r' && x!='\n')
     string[i++]=x;
     string[i]='\0';
     if(sendata==true)
    {
     if(x=='O'||x=='o')
     digitalWrite(13,HIGH);
     else if(x=='F'||x=='f')
     digitalWrite(13,LOW); 
    } 
     if(i==3 && strcmp(string,"CMD")==0)
    {
     delay(1000);
     Serial.flush();sendata=true;
     i=0;
    }

 }
     if(sendata==true)
    {
     delay(2000);
     Serial.print("BLueLink SILVER is sending data");
    }  
}

/****************************************************************************************

The following program turns the LED( 13th pin of Arduino board) ON when letter 'O' or

'o' is pressed and turns OFF the same LED when 'F' or 'f' is pressed (slave mode) .

BOARD : Arduino Duemilanove

****************************************************************************************/

#include<string.h>

char string[30];

boolean sendata=false;

void setup()

{

Serial.begin(115200);

pinMode(12,OUTPUT);//reset

pinMode(13,OUTPUT);//Onboard LED status

digitalWrite(12,LOW);

delay(20);

digitalWrite(12,HIGH);

delay(1000);

Serial.print("$$$");

}

void loop()

{

static int i=0;

static char x;

if(Serial.available()>0)

{

x=Serial.read();

if(x!='\r' && x!='\n')

string[i++]=x;

string[i]='\0';

if(sendata==true)

{

if(x=='O'||x=='o')

digitalWrite(13,HIGH);

else if(x=='F'||x=='f')

digitalWrite(13,LOW);

}

if(i==3 && strcmp(string,"CMD")==0)

{

delay(1000);

Serial.flush();sendata=true;

i=0;

}

if(sendata==true)

{

delay(2000);

Serial.print("BLueLink SILVER is sending data");

}

3. Testing BlueLINK-SILVER module with PIC Micro-controller

Bluelink SILVER Bluetooth module can also linked to PIC microcontroller. Here we have used PIC16f877A microcontroller for testing the Bluelink SILVER Bluetooth module.The connections are clearly shown below:

/****************************************************************************************
The following program turns the LED( connected to RB3 of PIC16F877A)ON when letter 'O'
or 'o' is pressed and turns OFF the same LED when 'F' or 'f' is pressed (slave mode) .
****************************************************************************************/

#include<pic.h>
#include<string.h>
void USART(const char *USART);
#define  TxF  while(!TRMT);	
char Rx;
int OK=0;

int count=0;                                     
void main()
{
TRISB=0x00;
PORTB=0x00;                            //setting PORTB as output port
TRISC=0X80;
TXSTA=0X24;                                                    
RCSTA=0X90;
SPBRG=0X81;                            // setting baud rate as 9600
INTCON=0XC0;
PIE1=0x20;
USART("$$$\r\n"); 
while(1);                            //sending $$$ command
                                     //checking for OK received                                           
}

/****************************************************************************************
Function    : interrupt isr()
Description : interrupt service
****************************************************************************************/

void interrupt isr()
{
RCIF=0;
Rx=RCREG;
if (Rx=='C')						
OK=1;
if (Rx=='M')						
OK=2;

if (Rx=='D')
OK=3;

if(OK==3){
	if (Rx=='o'||Rx=='O')	
         PORTB=0XFF;
	if (Rx=='f'||Rx=='F')	
         PORTB=0X00;
	}

	}
}

/****************************************************************************************
Function    : USART(const char *USART)
Description : transmiting string of data
****************************************************************************************/

void USART(const char *USART)	
{	
	while(*USART!='\0'){
	TXREG=*USART;
	TxF;USART++;}	
}

/****************************************************************************************

The following program turns the LED( connected to RB3 of PIC16F877A)ON when letter 'O'

or 'o' is pressed and turns OFF the same LED when 'F' or 'f' is pressed (slave mode) .

****************************************************************************************/

#include<pic.h>

#include<string.h>

void USART(const char *USART);

#define TxF while(!TRMT);

char Rx;

int OK=0;

int count=0;

void main()

{

TRISB=0x00;

PORTB=0x00; //setting PORTB as output port

TRISC=0X80;

TXSTA=0X24;

RCSTA=0X90;

SPBRG=0X81; // setting baud rate as 9600

INTCON=0XC0;

PIE1=0x20;

USART("$$$\r\n");

while(1); //sending $$$ command

//checking for OK received

}

/****************************************************************************************

Function : interrupt isr()

Description : interrupt service

****************************************************************************************/

void interrupt isr()

{

RCIF=0;

Rx=RCREG;

if (Rx=='C')

OK=1;

if (Rx=='M')

OK=2;

if (Rx=='D')

OK=3;

if(OK==3){

if (Rx=='o'||Rx=='O')

PORTB=0XFF;

if (Rx=='f'||Rx=='F')

PORTB=0X00;

}

/****************************************************************************************

Function : USART(const char *USART)

Description : transmiting string of data

****************************************************************************************/

void USART(const char *USART)

{

while(*USART!='\0'){

TXREG=*USART;

TxF;USART++;}

}

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Frequently Asked Questions(FAQ):

Q. In which situations BlueLINK-Silver is chosen for data transfer?
Ans. BlueLINK-Silver is chosen as Bluetooth module is if the distance between the System and target board is less.

Q. In which frequency band does the data transfer process fall in?
Ans. The data transfer process fall in RF band of the frequency spectrum.

Q. is any external antenna required for sending asnd receiving data?
Ans. No external antenna is required since the module comes up with inbuilt on-chip antenna.

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