Bluetooth (1) several terms and descriptions

Several terms:

HFP (hands-free profile) headset mode:

Allows a bluetooth device to control the phone number, such as answering, hanging up, rejecting, And dialing the voice. The rejection and dialing depend on whether the Bluetooth headset and phone number are supported.

HPS (handset profile) headset Mode

Used to support use between Bluetooth headsets and mobile phones

Hid () Man-Machine Interface Device Configuration File

The hid configuration file defines the protocols, programs, and functions used by bluetooth hid (such as keyboards, pointing devices, game devices, and remote monitoring devices ).

Dial-Up Network configuration file (Dun)

Dun provides standards for using Bluetooth wireless technology to access the Internet and other dial-up services. The most common case is to dial up on a mobile phone and connect to the internet wirelessly from a laptop.

Personal LAN configuration file (PAN)

Pan describes how two or more Bluetooth devices form an instant network and how to use the same mechanism to connect to a remote network through a network access point. Configuration File roles include network access points, group instant networks, and LAN users.

SDP (Service Discovery Protocol) Service Discovery Protocol

It provides the service that the application finds available in the Bluetooth environment and determines the features of those available services.

Gap (Generic Access Profile) Universal Access Application

Generally, the access application specification defines how a bluetooth device discovers and establishes secure (or insecure) connections with other devices. It handles some common business (such as inquiry, naming, and search) and some security issues (such as guarantees ), it also processes connection-related services (such as link establishment, channel establishment, and connection establishment ). Gap specifies some general running tasks. Therefore, it is mandatory and serves as the basis for all other Bluetooth Application specifications.

Notes

1.To avoid interference from the ISM frequency band, Bluetooth uses a variety of technologies.

-ARQ)

-Cyclic redundancy check "(CRC)

-Forward correction (FEC)

-Time Division Duplex and group exchange technology.

-Frequency hopping technology

2. Bluetooth Network Communication Process

1) when a bluetooth device is not connected, it is in sleep mode-standby mode ). In this mode, it wakes up every 1.28s or 2.56s and selects a channel to listen for the information sent to it.

2) A device initiates a connection, and the device will become the main unit of the network.

3) when a connection is initiated, the master unit may not know the existence of other devices and their addresses. At this time, the main unit

You must first perform the query (Inquiry) operation.

4) with the addresses of other devices, you can perform page operations to establish a connection.

5) after the connection is complete, data can be transmitted through communication.

6) during communication, the master and slave units exchange and send messages. The Master Unit depends on the data traffic of the slave unit.

Determines when to send and receive data from the slave unit.

7) if the data does not need to be sent and received from a unit, it switches to the hold mode until the main unit sends data again.

Information is sent to it. During this period, the Main Unit regularly sends information to it so that the slave unit synchronizes to the frequency-hopping channel, and does not need to listen to the channel for the rest of the time.

8) after the data transmission is complete, you can use the detach command to end the connection. In this way, the unit goes back to the standby mode.

9) connection status transition diagram

3.Three low-power modes for Bluetooth device connection

Sniff Mode

In this mode, the period of sending and receiving information from a unit is longer, and the master unit can only send information at the specified time slot.

Hold Mode

In this mode, only the internal clock is running in the slave unit, but once this mode is switched, the slave unit can send and receive information immediately. In this mode, the slave unit can participate in another micronetwork, so it can be used to connect several micronetworks.

Park mode

This mode is enabled when the slave unit does not participate in communication but still wants to synchronize with the frequency-hopping channel.