Bluetooth Troubleshooting Guide for Mobile App developers
It is important to start by noting that Bluetooth wireless technology is a wireless standard and specification that product manufacturers build into their products. The manufacturer who produces the Bluetooth enabled product does so in compliance with an industry standard but integrates the technology into its product in its unique way. Therefore, for technical support for Bluetooth enabled products, consumers should ultimately rely on the product manufacturer.
There are a few things you need to think about to get Bluetooth devices to work together. The most obvious being, of course, that you will need Bluetooth wireless functionality in all devices you want to connect. If you are not sure whether your devices contain Bluetooth technology, you will need to contact the manufacturers of the devices or check the products’ technical specifications.
- Make sure that the corresponding Bluetooth profile exists in both devices.
- Make sure the devices have Bluetooth functionality switched on.
- Make sure that the devices you want to communicate with are paired with each other (exceptions exist, for example, when transmitting business cards).
- Initiate a communication session.
Have you done everything right and it still doesn’t work? Below you will find some general tips of how to deal with potential problems in regard to Bluetooth connectivity and how to easily establish Bluetooth connections.
Making sure profiles match
For devices to work together it is important that each device that communicates share the same profile. Some examples:
- If you want to connect a headset to a mobile phone you will need the Hands-Free Profile (HFP) in both devices.
- If you want to establish a dial-up session to reach the Internet from a PDA connected to a mobile phone, you would need the Dial-Up Networking (DUN) Profile in both devices.
- If you want to print from a mobile phone to a printer, both devices typically will need the Basic Printing Profile (BPP). These are just some examples, but when purchasing devices you need to keep this concept in mind to make sure that they will work together as expected. Usually you will find information about what profiles are supported in the user manual.
An example that is not likely to work together:
- A mouse, which typically supports the Human Interface Device (HID) Profile, and a camera are unlikely to work together since presently no cameras support the HID profile.
Number of Bluetooth Profiles
Currently there are 25 BT profiles. Below is the current list of Profiles defined by the Bluetooth SIG:
- Advanced Audio Distribution Profile 1.2
- Audio/Video Remote Control Profile 1.4
- Basic Imaging Profile (BIP)
- Basic Printing Profile (BPP) 1.2
- Cordless Telephony Profile (CTP)
- Device Identification Profile (DI) 1.3
- Dial-Up Networking Profile (DUN)
- Fax Profile (FAX)
- File Transfer Profile (FTP)
- Generic Audio/Video Distribution Profile 1.2
- Generic Object Exchange Profile (GOEP)
- Hands-Free Profile 1.5 (HFP 1.5)
- Hardcopy Cable Replacement Profile (HCRP) 1.2
- Headset Profile (HSP)
- Health Device Profile (HDP)
- Human Interface Device Profile (HID)
- Intercom Profile (ICP)
- Object Push Profile (OPP)
- Personal Area Networking Profile (PAN)
- Phone Book Access Profile (PBAP)
- Serial Port Profile (SPP)
- Service Discovery Application Profile
- SIM Access Profile (SAP)
- Synchronization Profile (SYNC)
- Video Distribution Profile (VDP)
Note that it is unlikely every device needs to support all above profiles. Manufacturer often decide what the anticipated use of their device’s BT functionality is likely to be and accordingly bundle the necessary profile in their phone firmware. So, don’t assume things. Sometimes, even manuals are wrong.
Bluetooth functionality must be switched on
For devices to communicate using Bluetooth wireless technology you will need to make sure that both devices have the Bluetooth functionality turned on. Even though the basic design of Bluetooth provides for extremely low power consumption, the functionality can be switched off to save even more power, or to disable radio functionality in special situations such as during airplane take off. In most devices the Bluetooth functionality (radio) is switched on by software. This is typically done from a menu choice, “Turn Bluetooth radio on.”
Normally, for security reasons, two Bluetooth devices always need to be initially paired before they can exchange data. The term, pairing (or bonding as it is sometimes referred to), normally means that two devices are exchanging protected passkeys. Once paired, all information sent over the Bluetooth link is encrypted and will only be able to reach devices that are authorized to do so by the pairing process. In certain instances it may not be necessary to conduct the pairing procedure. For example, when exchanging business cards between two mobile phones it may be too cumbersome to pair with a password. Usually there is a setting in the device, for such cases, in which you can set a lower level of security.
Typically a pairing is done in two ways, depending on the type of devices. For example, pairing a headset and a mobile phone necessitates setting one of the devices into pairing mode and activating the pairing from the other device.
- Headset is set into pairing mode, typically by specific sequence of button pushing.
- In the mobile phone, the pairing is initiated by activating this function from the appropriate menu.
With many devices, especially those that have built-in Bluetooth functionality, there is no need to perform additional operations to establish a connection once paired. Typically, a mobile phone will automatically connect to the headset when a call is initiated. If at any time a pairing or connection between two devices needs to be re-established, the pairing should be conducted in a private, secure location.
Host/guest and multipoint
For each small personal network (piconet) of between two and seven devices, one device always acts as host and the other units are guests. All devices, independent of capability, can take both host and guest roles. If you have many devices connected in a personal network (more than one guest to a host) it is called multipoint. A computer, for example, could simultaneously connect and transmit data to a PDA, a camera, and a mobile phone at the same time. However, some devices, like wireless headsets, cannot maintain more than one simultaneous connection.
Cannot pair devices
In general, pairing between devices is not a problem; however, you will need to know how to initiate and facilitate the initial pairing, which is described briefly above and for greater detail see Connecting Devices.
Most common problems are:
Devices cannot be found
Bluetooth is off or the other device is not in “discoverable mode”. Make the unit you are trying to find and pair with visible/discoverable by either turning this on from the appropriate menu or by a sequence of keystrokes usually on devices with limited user interface. When you are done pairing, you can turn the device back to non-discoverable if you have security concerns.
“Pairing unsuccessful” message appears
The pair attempt between two devices failed. Usually this is the case when a wrong passcode or PIN is entered when trying to pair. If you are certain the passcode is correct, try powering down and then powering up both devices.
Another common cause is, of course, that it is difficult to find the right commands or menus for making connections. This is more difficult to answer since it depends very much on the manufacturer implementation and the user interface of the device. The only recommendation we can provide is to look in the user documentation and/or to contact the device manufacturer’s support department.