Bluetooth on Android-What is it and How it Works


Most Android devices are equipped with Bluetooth.

bluetooth-logoBluetooth is a wireless networking protocol (like WIFI) designed to quickly and automatically connect devices like printers, PDAs, Cameras etc. to computers, and to each other without wires.

Common Bluetooth applications are:

  • Connecting mobile phones/tablets to each other to exchange pictures,ring tones, music etc
  • Connecting computer peripherals like mice, keyboards, printers etc to a computer,tablet or phone.
  • Connecting headsets to mobile phones for hands free operation (Bluetooth car kits)
  • Connecting smart watches and wearable devices to your tablet/phone.

Bluetooth uses low power, low cost transmitters, and receivers with a range of 10-100 meters making it ideal for mobile use.

Bluetooth devices automatically detect and contact each other making communication between devices very easy.

Bluetooth Versus WIFI

Because both technologies are associated with computers,tablets and mobile phones there is considerable confusion as to which one to use or which one should be used.

WIFI is the wireless equivalent of Ethernet making fast data transfer
possible between computers. It is the choice for connecting computers together in a Home/Office environment, and connecting tablets/phones to the Internet or home/office Network.

Bluetooth can connect computers together, but the data transfer rate between the computers is too slow to be off practical use.

It is more commonly associated with connecting  low speed peripheral devices like mice and keyboards.

Bluetooth Class and Standards

Bluetooth devices come in three classes 1-3. The device class determines the effective operating range/distance of the the device.

Class 1 devices have a range up to 100m, class 2 devices up to 30 meters and aclass 3 device up to 10 meters.

Bluetooth is still being actively developed and the standard has already been through a number of versions. Each version is backwards compatible with the last making it possible to inter-operate devices with different version numbers.

The current Bluetooth standard is at version 4.0, Wikipedia has more technical details on the different standards and the differences.

Bluetooth Pairing

There are two pairing mechanisms

Legacy pairing which was only method available in v2.0 and previous versions,and Secure Simple Pairing (SSP) which is available in v2.1 and above.

v2.1 devices can use legacy pairing to connect to v2.0 and earlier devices.

Bluetooth devices can automatically discover other Bluetooth devices
that are within range if discovery is enabled.

However the discovery process takes time and the device connection must be approved.

This is obviously not satisfactory for devices that must always be in contact with each other like a blue tooth keyboard and mouse or an in car hands free kit, and the mobile phone.

Device pairing makes an effective permanent connection between the two devices so that they always connect without following the normal discovery process.

In legacy pairing the connection is made by assigning the devices a shared passkey (PIN) which they use to authenticate each other.

The process will vary slightly depending on the device but the
general process for pairing two devices (Device A and B) is.

  • Switch on both devices
  • Device A should detect device B
  • Select Pairing on device A and enter the PIN (passkey)
  • Device B will ask the user for the PIN. Enter the same PIN
    (passkey)
  • You should get confirmation that the devices are paired.

For devices that don’t allow you to enter a PIN the PIN (headsets) is fixed and is usually 0000 or 1234.

Other devices may be restricted in character sets i.e. they may only allow numbers and you must take this in consideration when assigning a PIN.

Secure Simple Pairing (SSP) uses a variety of pairing mechanisms and is able to detect the capabilities of the connecting devices.

However the main mechanism also uses a PIN called a passkey which is 6 digit numeric code.

Here is a useful video that shows how to transfer a picture from a mobile phone to a PC using bluetooth that illustrates the pairing process.

Enable/Disable Bluetooth

To enable or disable bluetooth go to Settings>Wireless & Networking and select bluetooth. You can now toggle it on or off.

bluetooth-on-off

You can tell if it is enabled as when on you should see the bluetooth icon to the op right of your screen.

bluetooth-icon-on

If you are not using it you should disable it to save power.

Playing Music Through Bluetooth

One of the most common applications if for playing music that is stored on your phone or tablet on Bluetooth speakers in the home or through a car stereo.

To do that you will need to pair your tablet/phone with the Bluetooth speakers and use a media player like VLC App- Media Player App to play the music.

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