Smartphones have become a must-have digital device, and the growing number of applications centered on smartphones is also enriching people's lives. As a user, mobile phone users want a better application experience and more application choices. From the iPhone6, Huawei MATE7, Samsung GALAXY Note 4, S6 and Nubian Z9, it can be seen that mobile phone manufacturers are adopting higher performance processors to improve the performance of the whole machine. Provide users with a new app experience. New features such as health and medical-related features, mobile payments, and wireless charging have become the trend of design.
First, let's review some of the new technologies and applications that mobile phone manufacturers have demonstrated and the technologies involved.
1, health and medical related functions
Samsung GALAXY Note 4 can monitor Cinga professional coaching services, heart rate monitoring, UV index monitoring and other functions in addition to regular indicators such as exercise mode and distance, calories burned. Apple also offers HealthKit, which works closely with health and fitness apps to provide heart rate, calories burned, blood sugar, cholesterol and more.
Wearable smart health devices and smartphone connections mostly use BLE as a means of wireless transmission. BLE has low power consumption, low cost, fast connection and good compatibility. It is suitable for low power consumption and high compatibility requirements of mobile phone accessories and other smart devices. Moreover, the newly released BLE4.1 standard of the Bluetooth organization upgrades the BLE4.0 standard, improves the transmission rate, supports the conversion of the Slave and Master roles, and improves the pairing mode to make BLE4.1 more suitable for wearable smart devices.
2, hardware support mobile payment
The mobile wallet is considered a new payment method that will replace a large number of credit cards and cash. Apple introduced Apple pay, Google launched Google Wallet, and Softcard offers similar payment methods. Apple Pay, Google Wallet and Softcard all use NFC technology as the data channel for identity authentication and data exchange during payment. NFC evolved from the integration of contactless radio frequency identification (RFID) and interoperability technologies, and is a technology for short-range wireless communication. Samsung is the most active mobile phone manufacturer to promote NFC technology in mobile applications. Its various mobile phones use NFC technology. For example, Samsung Galaxy S5 adopts NXP PN547, and Apple has followed the NXP PN65V in iPhone6.
Moreover, NFC can be used not only as a payment means on the smartphone side, but also in the pairing of Bluetooth and wifi of smart devices.
3, better audio characteristics
Smartphones are increasingly becoming platforms for multimedia applications, so the demand for smartphone audio features is growing. For example, from only 8bit, 8KHz voice services to 16bit, 44.1KHz Hi-Fi services. And with the improvement of audio characteristics, the requirements for hardware tuning are getting higher and higher. Therefore, the improvement of audio characteristics has become one of the focuses of mobile phone manufacturers.
4, wireless charging technology
Smartphones consume a lot of power, and “one-day charging†is almost a hot spot for every smartphone user. Wireless charging technology will greatly enhance the convenience of smartphones. Qi's wireless charging standard is currently the most widely used standard. Its low-power standard uses inductors to transmit 5W or less of power and transmits energy inductively. The distance between the two inductors (coils) can reach 5mm, and can be increased to 40mm as needed. Samsung's S6 supports wireless charging devices based on the Qi standard.
Below we discuss some issues and types of design considerations for BLE, NFC, and wireless charging and mobile audio amplifiers.
BLE
Several BLE chips commonly found in the market include NXP's QN902x (QN902x was previously Kuntianke products, and later Kuntianke was acquired by NXP), TI's CC254x and the newly released CC2640.
The more common problem is that the same program works fine on the development board provided by the factory. However, if the customer's own circuit board is not connected to the mobile phone, it will be interrupted after a period of connection, but the test power supply voltage meets the requirements. I can't do anything about it. In fact, these two problems are likely to be related to the crystal deviation used, which should be said from the BLE protocol standard and crystal selection.
The BLE chip usually requires two crystals. One high-frequency crystal is responsible for clocking the phase-locked loop of the RF section. A low-frequency 32.768KHz crystal is responsible for providing the wake-up clock after entering the low-power mode.
A slave device will enter the broadcast state after power-on, and send broadcast frames on the 37, 38, and 39 channels. If the master device scans to the slave device, it will connect and exchange data.
When a slave device is in the broadcast state, if the mobile phone or the packet sniffer does not hear the broadcast frame at this time, it is likely that the center frequency of the transmission is deviated. In the BLE protocol, the frequency offset of the modulation is not greater than 150KHz. If the frequency offset of the center frequency is greater than 50KHz, communication may not be possible, as shown in the following figure.
The deviation of the center frequency is related to the deviation of the high frequency crystal, that is to say, the larger the deviation of the high frequency crystal, the larger the deviation of the center frequency point.
If the connection is disconnected after a certain time has elapsed after the Slave and Master are connected, the problem is most likely caused by the deviation of the ground crystal. After entering the connection state, the Master will send CONNECT_REQ to maintain the connection state every time, this time is called connInterval (connSlaveLatency=0). Between two connIntervals, Slave puts it to sleep (after all, it's a low-power device, if it's always in accept mode, how can power consumption drop?). If the frequency of the low-frequency crystal is not accurate, it will cause a deviation in the wake-up time. If CONNECT_REQ is missed, the connection will fail. Of course, you can also increase the time window for Slave wakeup, but it will definitely increase the power consumption.
The QN9021 has a built-in 32.768KHz RC oscillator, and users can also use an external high-precision 32.768KHz crystal, which provides a flexible choice for low-power design.
NFC
In the NFC system design, the antenna design is a difficult point, and the designer can only balance the antenna size and communication distance. If you want to increase the communication distance without increasing the size of the antenna, you can only increase the signal strength of the drive.
NXP's PN66T module has a built-in 5V driver to reduce the antenna by 25%, and in card mode, the antenna size is reduced by more than 3 times. The balance between antenna size and communication distance can be well achieved.
audio amplifier
Mobile audio hardware, mainly including DSP (digital signal processor), Codec (codec, including DAC and ADC) and amplifier. Among them DSP is generally integrated in the mobile phone processor SoC, Codec is also integrated in the chip, the amplifier is outside the main chip.
In order to achieve better sound quality and greater output volume, increasing the driving voltage for driving the speaker has always been a design requirement. The TFA9890 speaker driver IC, which can be boosted to 9.5V, provides a larger voltage margin for the amplifier and prevents the amplifier from clipping.
Smartphone manufacturers have improved their hardware performance from simple attention to focusing on improving hardware performance while focusing on providing more applications that are close to life to enhance the user experience. The traditional IC manufacturers as the upstream of the industry chain have also adapted to this change, and strive to provide complete solutions to help smart phone manufacturers simplify the design process, shorten the time to market, and provide APP developers with more imagination. NXP also provides a matching MIFARE SDK that provides access to all hardware features at the Java level, optimizes the development of Android applications that interact with NTAG devices, and simplifies the system design flow and cycle of handset manufacturers.
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