1. First, please open the settings application on the iPhone home screen.
2. In the settings list, click the Bluetooth bar.
3. By default, Bluetooth is on. If it is not open, please open it. Here you can see that the iPhone has connected multiple Bluetooth devices, including Apple Watch and other Bluetooth devices.
4. After preparing the iPhone, please prepare the Bluetooth device connected to it. As shown in the figure below, take connecting a Nokia Bluetooth headset as an example.
5. When the 5.iPhone connects to Bluetooth for the first time, it needs to be paired, just like two people know each other and need a chance. At this point, the Bluetooth device needs to enter the pairing mode. Different Bluetooth devices may have different pairing methods. Please refer to the Bluetooth device manual for operation. Under normal circumstances, Bluetooth devices have a power-on key. In the power-off state, press and hold the power-on key for a long time to enter the pairing state, and the indicator light on the Bluetooth device will flash.
6. After putting the Bluetooth device into pairing mode, return to the Bluetooth list of iPhone. At this time, you can see a Bluetooth device under the device column, and click it to connect.
7. After the connection is successful, the Bluetooth device will appear in the device list.
Bluetooth is a wireless technical standard, which can realize short-distance data exchange between fixed equipment, mobile equipment and personal area network of buildings (using UHF radio waves in ISM band of 2.4 ~ 2.485 GHz). Bluetooth technology was first invented by telecom giant Ericsson in 1994 as a substitute for RS232 data line. Bluetooth can connect multiple devices, which overcomes the problem of data synchronization.
Today, Bluetooth is managed by the Bluetooth Special Interest Group (SIG). The Bluetooth Technology Alliance has more than 25,000 member companies in the world, which are distributed in many fields such as telecommunications, computers, networks and consumer electronics. IEEE lists Bluetooth technology as IEEE 802. 15. 1, but this standard is no longer maintained. Bluetooth Technology Alliance is responsible for supervising the development of Bluetooth profile, managing certification projects and maintaining trademark rights. The manufacturer's equipment must meet the standards of Bluetooth Technology Alliance before it can enter the market in the name of "Bluetooth equipment". Bluetooth technology has a set of patented networks that can be distributed to devices that meet the standards.
Name and icon:
The word "Bluetooth" is the Scandinavian word Bl? tand / Bl？ Tann (that is, old Norwegian blát? Nn), which is the nickname of harald Bluetooth, a king in 10 century. He unified the disputed Danish tribes into a kingdom, and it is said that he also introduced Christianity. The idea of naming Bluetooth after this was first put forward by Jim Kardach in 1997. Kardach has developed a system that allows mobile phones to communicate with computers. He was inspired by the historical novel Long Ships written by Frans G. Bengtsson, which described Viking and Harald Bluetooth King in harald, which means that Bluetooth will also unify the communication protocol into a global standard.
Frequency hopping technology:
The frequency band of Bluetooth is 2400_2483.5MHz (including the protection frequency band). This is a 2.4 GHz short-range radio band, and it is an industrial, scientific and medical (ISM) band that does not need permission (but is not unregulated) on a global scale.
Bluetooth uses frequency hopping technology to divide the transmitted data into data packets, and transmits the data packets through 79 designated Bluetooth channels. The bandwidth of each channel is 1 MHz. Bluetooth 4.0 uses a spacing of 2 MHz and can accommodate 40 channels. The first channel starts at 2402 MHz and reaches 2480 MHz every 1 MHz. Using the adaptive frequency hopping (AFH) function, it usually hops 1600 times per second.
At first, Gaussian frequency shift keying (GFSK) modulation was the only available modulation scheme. However, Bluetooth 2.0+EDR makes it possible to use π/4 DQPSK and 8DPSK modulation in compatible devices. It is said that devices running GFSK can run at the basic rate (BR), and the instantaneous rate can reach1mbit/s. The term enhanced data rate (EDR) is used to describe π/4-DPSK and 8DPSK schemes, which can reach 2 and 3Mbit/s respectively. In Bluetooth radio technology, the combination of two modes (BR and EDR) is collectively called "BR/EDR RF".
Bluetooth is a packet-based protocol with a master-slave architecture. In the same piconet, the master device can communicate with up to seven slave devices. All devices * * * enjoy the master clock. Packet switching is based on the protocol defined by the master device, and the protocol is 3 12.5? S is the basic clock that runs at regular intervals. Two clock cycles form a 625? S slot, two time gaps form a 1250? The gap of s is right. In the simple case of single slot grouping, the master device sends information in even slots and receives information in odd slots. Slave devices are just the opposite. The packet size can be as long as 1, 3 or 5 slots, but in either case, the master will start transmission from even slots and the slave will start transmission from odd slots.
Communication connection:
A Bluetooth master device can communicate with at most seven devices in a piconet (a temporary computer network using Bluetooth technology), although not all devices can reach this maximum. Devices can change roles through protocols, and slave devices can also be changed into master devices (for example, headphones initiate a connection request to a mobile phone, and naturally the master device is the initiator of the connection, but it may run as a slave device later. )
Bluetooth core specification provides two or more piconet connections to form a distributed network, so that specific devices can automatically play the roles of master and slave respectively in these piconets.
Data can be transmitted between the master device and other devices at any time (except the rarely used broadcast mode). The master device can select the slave device to access; Usually, it can quickly switch between devices in a rotating way. Because it is the master device that chooses the slave device to access, theoretically, the slave device should stand by in the receiving slot, and the burden of the master device is less than that of the slave device. The master device can connect with seven slave devices, but it is difficult for the slave devices to connect with more than one master device. The specification is vague about the behavior requirements in the scattering network.