NFC-based E-wallet Design

- Apr 03, 2018-

NFC, short-range wireless communication, is a wireless technology initiated by NXP that is jointly promoted by famous vendors such as Nokia and Sony. It combines inductive readers, proximity cards, and peer-to-peer functions on a single chip. Recognize and exchange data with compatible devices within a short distance.

Background

NFC has the characteristics of two-way connection and identification. It works in the 13.56MHz frequency range and its working distance is close to 10cm. NFC technology promotes standardization within the framework of ISO18092, ECMA340, and ETSITS102 190. It is also compatible with the widely-used ISO14443 Type-A, B, and Felica standard contactless smart cards.

The PN544 complies with the latest NFC specifications developed by the European Telecommunications Standards Institute (ETSI) and provides mobile phone manufacturers and telecom operators with a fully compliant platform for the rollout of next-generation NFC devices and services: The PN544 is fully compatible with all the now-launched single-line products. Protocol (SWP) NFC specification that connects the SIM card to the Host Controller Interface (HCI).

The PN65O is the SmartMX security module of the PN544 plus NXP. The PN544 and PN65O hardware PINs are fully PIN compatible. At the same time, the PN65O/PN544 offers a variety of host interface options to ensure that handset manufacturers can easily integrate High Speed UART, SPI, I2C, and support multiple RF interface protocols: ISO14443A/B, ISO15693, MIFARE, Felica. In addition, NXP Work closely with leading SIM card manufacturers such as Gemalto, Oberthur Technologies and Giesecke & Devrient to ensure the interoperability of SWP interfaces including MIFARE technology.

PN544 and PN65O Advantages

(1) Small size for easy size optimization

(2) Low power consumption

(3) Battery Shutdown and Low Battery Operation Mode

(4) Optional platform-independent software stack

(5) Provide GPIO PORT for external unit control

(6) Interrupting the IRQ makes the command communication of the external control unit easier

(7) Support security unit control interface

(8) Integrated Power Control Unit

About NXP's Newest NFC Wallet Solution

The NFC e-wallet function is a mobile phone as a trading platform. The PN544 NFC controller (PN65O has a built-in security module) and a security module are two major mobile payment and data exchange functions.

RF section

The NFC RF circuit is composed of four parts: an EMC filter circuit, a matching circuit, a receiving circuit, and an antenna.

EMC circuit

This system is based on an operating frequency of 13.56 MHz. This frequency is generated by a quartz crystal. At the same time, high-order harmonics will also be produced. In order to comply with the internal electromagnetic compatibility rules, the higher harmonics of the third, fifth, and fifth times of 13.56MHz must be appropriately suppressed. So the EMC circuit is configured as an LC low-pass filter to filter out higher harmonics.

Antenna matching circuit

Since the antenna coil itself is a low-impedance device, a matching circuit must be added between the antenna and the NFC IC in order to transmit the energy sent from the NFC IC to the antenna maximally. Eliminate energy loss due to signal reflection due to mismatch.