Connecting through Bluetooth

When we connect some devices together, one device can be a Mobile phone, one can be a DVD, one can be a digital camera, one can be a printer and all the devices which are connected, can be completely different devices. Every device has its own distinct purpose – a printer is supposed to print, a mobile phone is supposed to send and receive calls, and so on. The questions are:

  • How the connection gets initiated?
  • How do the Bluetooth technology talks, and interacts with the device’s native technology?
  • How the communication goes on?

To find the answer, let us discuss some more topics.

Initiating Connection:

All unconnected Bluetooth devices start out in the low-power Standby state. When one unit senses another Bluetooth device in the area, a connection procedure is initiated. At this time, the first device (the one that found the second unit) serves as master unit and creates a mini-network.

A Bluetooth device can issue two different types of commands to initiate the connection procedure.

Inquiry command
Page command

An inquiry command is issued when the identification number, or address, of the other device isn’t yet known. ie., at this time, the device searches for the next Bluetooth devices. Once the device’s address is known, a page command is issued. The page command is issued to “wake up” the other unit and establish a full connection between the two devices. When the slave unit wakes up, the data transmission can get started.
After initiating the connection, how the communications goes on?

Inducing Communication:

Everything happens in the communication with the Protocol stack inside the module. A protocol is simply a predefined set of instruction which gives out a precise way for devices to communicate with each other. All types of communications and networking technology include its own unique set of protocols which describes precisely how data is passed in various situations. Protocols define the data format, and how that data is to be sent and received. It forms a correct layer, and sequence of instructions, in which the repeatedly used protocols are on the bottom of the layer. This layer is called Protocol stack.

But, what are the protocols which initiate the communication?

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