Bluetooth + Arduino Tutorial

Bluetooth and its wonders. Set it up with Arduino and Attiny85!

Introduction

This is my very first tutorial and it is on Bluetooth with Arduino.  I feel this is necessary for the community as there are not so many of them out there. The ones that are floating around the web are highly outdated or just not to my taste. Sorry! I know I'm not the best one to do a tutorial either but I will try my best. I learned how to use the Seeeduino Bluetooth, or any Bluetooth the hard way. This is created to make it easier for you! 

note: When I was learning about how to add Bluetooth to my project I was following closely the Wiki page of Seeeduino Bluetooth Shield. Find it here. Also, I will be covering how to set up your Bluetooth as a slave. If you would like to learn how to set it up as a Master reference the link above.

I hope you enjoy this tutorial / how to

What you need, Arduino Bluetooth

What you will need for the first part of this tutorial (Bluetooth with Arduino not Attiny!!) is an Arduino Uno, I'm using version 3, and the Seeeduino Bluetooth Shield. You can use a different one by modifying the
tutorial slightly. In the second part of the tutorial I will introduce a different Bluetooth module and how to work it with the Attiny85. 

The list:

• Arduino Uno (I'm sure you can use others but I haven't had a chance to test)
• Seeeduino Bluetooth Shield

OK! We are Ready to Set Up! 

First of, lets connect everything like it should be. When you are placing your shield onto the Arduino make sure the analog side is on the analog side of the Arduino and the Digital on Digital. Make sure the pins are matching and just place it down and push it in.

We are ready to upload! I'm going to assume you have the Arduino software installed and you know how to upload a sketch to your Arduino. The only problem is that we don't have the code!

The Seeeduino Bluetooth Shield Code

This is my favorite part, the coding! 

Start off by opening up a new Arduino sketch. Fill in the usual aka Bare Minimum:

 void setup(){ }  
   
 void loop(){ }  

Now, for us to set up a communication via a serial port we can use a library called SoftwareSerial. Go to tools -> library and choose the SoftwareSerial library. Once you have it imported we can start using it.

For the first part we are going to set up the software serial port on Arduino channel 6 and 7. 6 being the receiving pin and 7 being the transmitting pin.

 #include            // this will include the software serial port library
 int rx_pin = 6;     // setting digital pin 6 to be the receiving pin
 int tx_pin = 7;     // setting the digital pin 7 to be the transmitting pin

 SoftwareSerial Bt(rx_pin,tx_pin); // this creates a new SoftwareSerial object on 
                                   // the selected pins!
 void setup(){ }  
   
 void loop(){ }  

OK, so far so good! The code is not doing much yet but we are getting somewhere. Now its time to set up the pinModes like so.

 void setup(){
 Serial.begin(9600); // this is a connection between the arduino and 
                       // the pc via USB
 pinMode(rx_pin, INPUT);  // receiving pin as INPUT
 pinMode(tx_pin, OUTPUT); // transmitting pin as OUTPUT

 bluetoothInitiate(); // this function will initiate our bluetooth (next section)
 }  

And now the Bluetooth as a slave. What this means that your android phone or your PC will be able to pair with it and send information back and forth. For this I will create a separate function to keep everything neat in the setup function.

 void bluetoothInitiate(){
 // this part is copied from the Seeeduino example*
 Bt.begin(38400); // this sets the the module to run at the default bound rate
 Bt.print("\r\n+STWMOD = 0\r\n");        //set the bluetooth work in slave mode
 Bt.print("\r\n+STNA=SeeedBTSlave\r\n"); //set the bluetooth name as "SeeedBTSlave"
 Bt.print("\r\n+STOAUT=1\r\n");          // Permit Paired device to connect me
 Bt.print("\r\n+STAUTO=0\r\n");          // Auto-connection should be forbidden here
 delay(2000);                            // This delay is required.
 Bt.print("\r\n+INQ=1\r\n");             //make the slave bluetooth inquirable
 delay(2000);                            // This delay is required.
 Bt.flush(); 
 Bt.print("Bluetooth connection established correctly!"); // if connection is successful then print to the master device
 }

Congrats! You can now connect to your Bluetooth, but it wont do much at all.
So... now we need to do something to receive the packets thrown at us from a PC or any other device.
For this we setup the RX pin and the TX pin, so lets put it to works.

 char buffer; // this is where we are going to store the received character
 void loop(){
 if(Bt.avaliable()){     // this will check if there is anything being
                           // sent to the Bluetooth from another device
   buffer = Bt.read();   // this will save anything that is being sent to the Bluetooth
   Serial.print(buffer); // this will print to the local serial (tools->serial monitor)
   }
 // this is for recieving on the device with bluetooth, now we can make it send stuff too!
 if(Serial.available()){   // this will check if any data is sent
                             // from the local terminal
   buffer = Serial.read(); // get what the terminal sent
   Bt.print(buffer);       // and now send it to the master device
   }
 }

Putty and COM

In order for us to communicate between the PC and Arduino via Bluetooth we have to establish a connection via COM. A really good and free program that we can use to establish a serial connection between the Bluetooth module and our PC is Putty. You can download it and read more about it here. Now once you have installed Putty we can move on to the next step. 

Power on your Arduino with the shield and the code already uploaded. Remember to restart the Arduino after you have uploaded the code. 

You should notice two leds flashing on the shield, red and yellow. This is good, now you can search for the module using your PC's Bluetooth software. It should be named SeedBtSlave. The pairing code is "0000" Once you have it paired with your computer we can start working our magic, but first we need to check what COM port we are running the Bluetooth connection on. We can do this by clicking start then typing "device manager". Open device manager and navigate down to Ports(COM&LPT), expand it. Now you should notice that you have two new things there. It should say "Standard Serial over Bluetooth link (COM#)" If it does, then you know that you paired your device correctly and are ready to start using it. NOTE: I have more than one Bluetooth device connected therefore there are 4 ports!

Note the COM number. (usually the top one out of the two) and lets go over to Putty. 

Open up Putty and select the "serial" radio button. Now set the COM# and the speed as 38400. This is what we used in the code*

At this point I would recommend that you restart your Arduino before proceeding to open the connection. When the red/yellow lights are flashing on the Arduino you are ready to connect! If everything went right you should see this screen:

Congratulations!!! This message has been sent over Bluetooth from your Arduino to your PC!
Now open your local terminal monitor (the USB connection between your PC and Arduino) and send messages between the two. I have used this to turn on and off LEDS and move SERVOS. Its heaps of fun and the limits are your imagination.

Later on this week I will post a tutorial building upon this and how to use a different Bluetooth module with the Attiny85. Stay tuned! I hope you enjoyed this tutorial, if you have any questions please comment. Also, keep in mind that this is my first tutorial and one of the first blog posts ever. If you do not understand something or if you would like to comment on anything do not hesitate to post.

Thanks for reading!