This series of articles are some knowledge points that I want to record after reading "Quick Introduction to Low Energy Bluetooth Technology" edited by Tan Hui. If readers want to know more about the specific information about the nrf51822 chip, you can read "Low Power Consumption". A Quick Start to Bluetooth Technology" book.
1. Bluetooth protocol
1.1. About Bluetooth 3.0 (2009)
The core technology of Bluetooth 3.0 is Generic Alternate MAC/PHY (AMP), which is an alternate radio frequency technology that allows the Bluetooth protocol stack to dynamically select the correct radio frequency for any task. AMP modifies the standard Bluetooth core architecture to use multiple alternate broadcasts below the L2CAP layer, while using standard Bluetooth radios for recovery and connection and matching.
In layman's terms, allowing consumer devices to use existing Bluetooth technology while achieving faster throughput by using a second wireless technology. The Bluetooth module is only used to create a pairing between two devices, and the data itself is done through the WiFi radio frequency. If one of the two mobile phones does not have a built-in WiFi module, the Bluetooth transmission speed will drop to the rate of Bluetooth 2.0.
1.2. About Bluetooth 4.0 (2010)
Bluetooth 4.0 includes traditional Bluetooth technology, high-speed Bluetooth technology and low-power Bluetooth technology.
1.3. About Bluetooth 4.1 (2013)
Four major improvements: (1) Better support for LTE (4G core technology). (2) Further reduce the reconnection time between devices. (3) The data transmission speed is optimized. (4) Support the IP6v standard to meet the requirements of the Internet of Things.
1.4. About Bluetooth 4.2 (2014)
The biggest improvement: support 6LowPAN, the low-power wireless personal area network technology based on the IP6v protocol. 6LowPAN is the first wireless communication standard that incorporates the IP protocol. This technology allows multiple Bluetooth devices to access the Internet or a local area network through one terminal based on IP.
In fact, most devices are not suitable for high-bandwidth, high-power WiFi access, and are more suitable for Bluetooth. Bluetooth 4.2 enables all Bluetooth 4.2 devices in the room to be connected to the home LAN without the participation of a mobile phone or PC, with only one or two Bluetooth-to-LAN access terminals in the same room. A large number of devices switching to Bluetooth will also reduce the parallel transmission pressure on the router on the WiFi side.
One big advantage: No need to update hardware for existing devices, only firmware upgrades are required to support, that is, a large number of existing Bluetooth devices may gain new network connectivity capabilities through a simple software update.
2. Other short-range wireless communication technologies
2.1、ANT
ANT wireless network is a low-power wireless network standard initiated and promoted by Dynastream, Nordic and other companies.
Advantages: 1) Very low power consumption. 2) The ANT wireless network has encapsulated the relevant wireless network protocols, anti-interference protocols, ultra-low power power management, etc. inside the chip. It only needs to configure the network of each node according to the application needs to complete the network construction and application. 3) The network deployment is extremely flexible, which can be point-to-point, star, tree or even mesh network.
2.2, ZigBee protocol
The ZigBee radio frequency transceiver "chip" is actually just a chip that conforms to the physical layer standard. It is only responsible for modulating and demodulating wireless communication signals. It must be combined with a single-chip microcomputer to complete the data transceiver and protocol implementation. Even the single-chip solution only inherits the RF part and the single-chip part, and does not include the ZigBee protocol. In both cases, users need to develop all software parts according to the structure of the microcontroller and the settings of the registers and refer to the IEEE 802.15.4 protocol in the physical layer part and the ZigBee protocol in the network layer part.
2.3. Near Field Communication (NFC)
NFC is evolved from the integration of non-contact radio frequency identification (RFID), that is, interconnection technology. It combines the functions of inductive card reader, inductive card and point-to-point on a single chip, which can identify and data with compatible devices within a short distance. exchange. Different from RFID, NFC has the characteristics of two-way connection and identification, works in the range of 13.56MHz, and has a working distance of about 10cm. The NFC chip is installed on the mobile phone, and the mobile phone can realize small-value electronic payment and read the information of other NFC devices or tags.