1 NFC smart TV system structure and overall design plan
This article is designed with Ti's TRF7970A Transceiver IC as a TV end, and RF430Cl330H NFCTAG is applied at the remote control terminal; in this system, the basic function is applied as follows:
· The TRF7970A can communicate with the RF430Cl330H to achieve pairs between televisions and remote controls, which is the pairing before 2.4GHz data transmission;
· TRF7970A can achieve fast pairing of WiFi with NFC smartphones;
· RF430CL330H can communicate with the smart phone to implement mobile phone data information to the remote control or on the TV;
· You can upgrade the software upgrade of Firmware through NFC's air interface;
· The TRF7970A can make a TV function item selection for the reading and writing of the label;
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Figure 1 System Structure Block Diagram
TRF7970A meets the three functions of NFC: Reader / Write, Pear to Pear and Card Emulaton fully meet ISO / IEC18092, ISO / IEC21481 NFC standards; interact with information that meets NFC standards, RF430CL330H is A dynamic NFC TAG chip, complies with NFC Type 4 standard, supported data rates up to 848kbps, and SPI interfaces can be effectively communicated with MCU.
2 hardware circuit design
2.1 TRF7970A Module Hardware Circuit Design
The TRF7970A is a 13.56MHz RFID high integration RF front-end chip that fully supports the NFC's protocol standard. By configuring the ISO Control register of the chip, it can be set to different modes of operation; TRF7970A supports SPI and parallel communication Interface mode, wide voltage (2.7V ~ 5.5V) power supply, internal integration of LDO, support 5 power management mode, output power up to 200MW in 5V power supply Receive loop has two (RX1 and RX2), phase phase difference is 90 degrees, ensuring the stability and reliability of the received, and the basic hardware circuit is as shown below:
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Figure 2 TRF7970A RF front-end circuit
The radio front end matches 50 ohm radio frequency impedance, and the basic matching network is as follows:
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Figure 3 TRF7970A RF Front Front Matching Network
2.2 TRF7970A Antenna Matching Circuit Construction
The TRF7970A antenna is a 50 ohm impedance matching antenna, and its basic matching circuit is as follows:
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Figure 4 TRF7970A Antenna Matching Circuit
Since the material and size of the antenna are different, each produced TRF7970A antenna matching circuit antenna must be a complete antenna match, according to the design system Q value, the antenna's inductance value of the radio frequency front end is completely matched. .
2.3 RF430CL330H module hardware circuit design
RF430CL330H is a dynamic label that meets NFC Type 4, supports ISO / IEC14443 Type B, supports SPI and I2C interfaces, a dynamic label with RF wake-up feature; its basic hardware circuit is as follows:
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Figure 5 RF430CL330H Basic Reference Circuit
As can be seen from this schematic, few peripheral devices can be integrated into other chip peripheral circuits to achieve fast NFC functions. In this remote control project, the RF430CL330H and peripheral circuits integrate to the remote control, just take the coil as a separate module, so that it is easy to read and write operations.
3 system software design
System software design mainly includes implementation of various functions in smart television applications: reads permission to TAG to obtain specific television or network programs, there is a quick establishment of Bluetooth and WiFi-paired demand for Bluetooth pairs of WiFi, TV can obtain mobile phone related pictures, link information, and realize fast switching of information through the P2P function. FirMware can also be wirelessly upgraded via NFC.
3.1 Label reading
The TRF7970A can support reads of ISO15693, ISO14443A / B (as shown in Figure 6).
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Figure 6 TRF7970A supported card standard, reading full text, technology area
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