"After jobs, Apple has never launched amazing products, and it seems very" low-key "step by step. At last year's developer conference, apple quietly launched ibeacon, the next new technology of ios7. Although there was no big publicity, ibeacon still attracted the attention of many people in the industry, because this may be another technology that has a far-reaching impact on Apple's future life.
Apple's retail stores in the United States have started the ibeacon service. When you walk into the store with an IOS device upgraded with ios7, you will push some reminder messages to you to establish a connection with permission. Imagine that in front of different counters, the mobile app pushes you the latest viewed product discounts and information according to your location. On the same interface, you can complete a series of operations such as coupon redemption and payment. All this extraordinary experience can be achieved through ibeacon.
What is ibeacon? Ibeacon is a proprietary trademark launched by apple for "indoor positioning system", and "a new low-power and low-cost signal transmitter can send a signal to inform ios7 equipment of its existence". In short, it is used for indoor positioning. Beacon translates as a lighthouse. The working principle of ibeacon is based on Bluetooth low energy (ble) low-power Bluetooth transmission technology. It can be said that it is Apple's nickname for ble. The ibeacon base station continuously sends Bluetooth signals to the surrounding area. When the intelligent device enters the set area, it can receive the signal. Apple has not built ibeacon into a closed technology system. As long as it meets ibeacon technology standards, it can be used, so Android can also support ibeacon. However, Google only supported ble technology in Android 4.3 very late, and only some flagship models are configured with ble at present.
Positioning has always been a very key function, especially in the era of mobile Internet. Different from the dominant position of GPS navigation in outdoor positioning, there is no very mature application in the field of indoor positioning. Through the deployment of ibeacon base station, indoor navigation can be realized, and information can be pushed through Bluetooth. Ibeacon can provide a great experience in shopping malls, retail or some public service fields such as gymnasiums and museums. In particular, Bluetooth has good transmission distance, low power consumption and signal encryption, which makes ibeacon very promising in the field of mobile payment. In short, the potential of ibeacon seems to be infinite and has attracted more and more attention.
To understand how ibeacon works, we first need to understand ble. Ble (also known as Bluetooth smart) dates back to wibree proposed by Nokia in 2006. Later, it was integrated into the Bluetooth standard and became a part of Bluetooth 4.0. At present, we often see three kinds of Bluetooth devices:
Bluetooth: Bluetooth devices that only support traditional mode
Bluetooth smart ready: supports both traditional and low-power mode devices
Bluetooth Smart: only low-power Bluetooth devices are supported
Compared with traditional Bluetooth, the biggest advantage of ble is to reduce power consumption by 90%, increase transmission distance (more than 100m), and improve security and stability (support AES encryption and CRC verification). Ibeacon also has some characteristics:
No pairing is required. Generally, Bluetooth devices need pairing. Ibeacon does not need to be paired because it uses Bluetooth broadcast channels to transmit signals.
The program can wake up in the background, and the information push of ibeacon needs app support. However, we do not need to open the app to receive the ibeacon signal, as long as it is installed and the mobile phone Bluetooth is turned on.
How does ibeacon work? In fact, the ibeacon base station continuously sends location information through the Bluetooth broadcast channel. The faster the transmission frequency, the more power consumption. In other words, ibeacon does not push messages, but is only used for positioning. The function of pushing messages must be completed by app. Apple has defined the data format of 32-bit broadcast in ibeacon.
Ibeacon packet format
UUID: manufacturer identification number
Major: it is equivalent to the group number. Beacon in the same group has the same major
Minor: it is equivalent to identifying a single beacon in the group
TX power: used to measure the distance between the equipment and beacon
UUID + major + minor constitutes a beacon identification number, which is somewhat similar to the IP address in the network. TX power is used for ranging. Ibeacon currently defines only about three rough levels:
Immediate: within about 10 cm
Near: within 1m
Far: 1m away
Apple has released the relevant technical specifications of ibeacon and invited hardware manufacturers for trademark certification. However, ibeacon is not a patented technology. Android systems that support LBE can also support ibeacon. At present, many manufacturers at home and abroad have launched products based on ibeacon, among which estimote is the most representative.
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Ti Bluetooth / 802.15.1 development tool -- cc2541emk
Cc2540 Mini development board, the attached "key card" circuit board can be used as ble peripherals
Estimote introduction
Estimote is the first start-up company to enter the field of smart retail. According to statistics, more than half of consumers shopping will carry smartphones. Stores can provide consumers with better experience and better services by deploying the estimate beacon platform. Estimote beacon is actually a small wireless device integrating some sensors, which can continuously broadcast weak wireless signals to the surrounding areas for intelligent devices to receive. At present, the commodity package provided by estimote includes three beacons in different colors for $99.
Estimote Beacons
How does estimote beacon work,
A very simple schematic diagram. When the customer approaches the store, beacon at the door sends a welcome message; After entering the store, beacon next to the goods will send discount information; When customers buy and leave, they can pay directly through beacon.
We know that ibeacon can only send positioning signals, and the real push message needs to install app in the mobile phone. Estimote has released the source code of SDK and demo program on its official website, which can be quickly used by developers to develop their own applications. Estimate provides an interesting virtual demo program (estimate visual beacon), which can be downloaded from the app store. There are three demonstration programs (distance, proximity prompt and notification message). The author tried the distance demonstration program, which can identify estimate beacon and display three distance ranges, but the accuracy is really not high.
Estimote Visual Beacon App
The most interesting thing is that you can experience virtual functions without even buying estimote beacon. App can virtualize the ios7 device supporting LBE into a beacon, so that your IOS device becomes an ibeacon base station.
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PmodBT2 – Bluetooth interface, UART, SPI interface, low power Bluetooth interface module
Estimote disassembly
The gemstone shape of estimote beacon is very beautiful. The back can be directly glued to wood, glass or smooth wall, which is very convenient to fix. The material adopts non-toxic silica gel with certain moisture absorption. Estimote claims to be able to work continuously for 2 years. This material provides good protection.
Blue estimote beacon
The entire estimote is sealed with silica gel and must be disassembled destructively. There is a problem. If it has to be replaced after two years after deployment. Let's see what's inside estimote.
Disassembly drawing
In fact, the things inside are very simple. A white PCB board is powered by button battery (cr2540). The design of white PCB still looks very beautiful. Take a closer look. The core device adopts Nordic's low-power Bluetooth SOC chip. At present, the popular Bluetooth chip manufacturers in the market mainly include Ti, CSR and Nordic. This nrf51822 is the latest SOC chip launched by Nordic for ble and 2.4GHz wireless applications. It also integrates the Cortex-M0 core, which will be introduced in detail later. From the PCB inside estimote, the peripheral circuit of nrf51822 is also very simple. The board is also equipped with temperature sensor and St accelerometer lis3dh. User app can flexibly call these sensor data.
Estimote internal PCB
At present, TI's ble scheme is still used more, and recently Ti announced that its low-power Bluetooth products support ibeacon. The cc2540 was used as the lost finder disassembled by Aiban. However, estimote chose Nordic's nrf51822, which is also very powerful. The love board forum once organized a group purchase of nrf51822 development board, which received a warm response. It can be seen that there are many pumps.
Estimote beacon block diagram
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nRF51822
Nordic is a fabless semiconductor design company in Norway, specializing in ultra-low power consumption (ULP) short-range wireless communication in 2.4GHz and lower than 1GHz frequency band. Its nrf24l Series RF chips are widely used. Nrf51822 is the first multi protocol Bluetooth / 2.4GHz dedicated RF SOC chip of Nordic's new nrf51 series. Nrf51 series integrates a new 2.4GHz multi protocol RF transceiver and a 32-bit arm Cortex-M0 core. Therefore, the power consumption is reduced by 50%, the RF performance is greatly improved, and the processing capacity is more than 10 times higher than that of the previous generation Nordic chip.
Nrf51822 is a 2.4GHz single-chip SOC with high performance and flexibility. It supports ble and 2.4GHz ULP wireless protocols. A 32-bit arm Cortex-M0 processor is built in, with 256Kb flash and 16kb ram. Its built-in 2.4GHz RF receiver not only supports low-power Bluetooth, but also is compatible with the previous nrf24l series wireless receiver.
nRF51822 SoC
Nordic is a member of the Bluetooth Technology Alliance (Bluetooth SIG). It contributes the core technology of ULP RF design to ble, which constitutes the iconic feature of Bluetooth 4.0. The multi protocol supported by nrf51822 frees designers from the constraints of a dedicated software framework. As a single-chip SOC, nrf51822 also has a very characteristic programmable peripheral interconnection system (PPI), which is built with a wealth of analog and digital peripherals, such as RF transceiver, timer and so on. These peripheral resources can be realized through PPI without processor interaction, so as to reduce processor activity time and save power consumption. 31 IOS can flexibly configure peripheral interfaces according to PCB wiring requirements. Nrf51822 adopts single power supply (1.8v-3.6v). It can use 1.8V direct power supply or built-in step-down DC-DC. Here are some features of nrf51882:
Built in 32-bit arm Cortex-M0 processor, 256Kb on-chip flash and 16kb ram;
It supports Bluetooth low-power protocol stack and is compatible with nrf24l series
16 PPI channels;
Configurable IO interface, 6x6mm 48 pin QFN package, providing up to 31 gpios;
"When LDO on chip is configured, the power range is 1.8-3.6v, and the LDO bypass mode is 1.75-1.95v;
Flexible power management can be provided for each peripheral resource to further reduce power consumption
Three data transmission rates (2Mbps / 1Mbps / 250kbps)
On chip pull-down DC / DC converter for 3V battery (e.g. button battery);
On chip + / - 250 ppm 32kHz RC oscillator, in Bluetooth low-power applications, no external 32kHz crystal is required, which can save cost and circuit board space;
6x6mm 48 pin QFN package, providing up to 32 gpios;
Nrf51822 provides a copyright free and updatable complete Bluetooth protocol stack and a popular Cortex-M0 development environment, which can simplify the design and development. Through disassembly, it is found that the hardware design of Bluetooth solution is not very complex, and the size can be designed very small. On the contrary, the biggest limitation is the battery size. It is very suitable for consumer electronics accessories, wearable devices, sports and health, toys and so on. The biggest advantage of ble equipment is power consumption. The following table is a simple comparison of mainstream products of several manufacturers, which is only used as a reference.
Power consumption comparison, for reference only
The launch of Bluetooth 4.0 has given Bluetooth greater vitality. With the support of IOS and Android, Bluetooth 4.0 will be more widely used when it becomes the standard configuration of mobile phones. Intelligent hardware, especially wearable devices, will be more popular. Bluetooth 4.0 can be said to be a very hot field now. Bluetooth has great potential. Apple's ibeacon may not only focus on this. With the improvement of Bluetooth Security (supporting AES encryption), Apple may pay more attention to mobile payment. Unlike Android's strong support for NFC, IOS devices have not been equipped with NFC, but turned to Bluetooth. If ibeacon successfully enters mobile payment, it will be a disruptive change to our ordinary life.
At present, the deployment of ibeacon is mostly in the experimental stage, and there are still many problems to be solved:
On the one hand, in terms of security, at present, the broadcast signal format of ibeacon is public, so it is easy to copy the broadcast signal of ibeacon base station, and the received IOS device cannot distinguish the authenticity. One solution is to add authentication information to the broadcast information.
On the other hand, RF signals are in transmission
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