STM32 Nucleo expansion board embeds boosted NFC
ams’ boostedNFC technology enables reliable NFC coupling in space-constrained devices, and is now implemented in a complete STM32 system development board, from ST, that plugs into Nucleo STM32 main boards. This provides a complete design blueprint for implementing NFC in applications such as IoT nodes, in which NFC can be used for configuration and network commissioning, and wearable devices, in which it may securely carry data for contactless payments, ticketing or access control.
The expansion board is supplied with a full suite of NFC firmware provided by ST for its ARM Cortex-M based STM32 microcontrollers. The NFC board is complemented by other expansion boards implementing fingerprint recognition, Bluetooth connectivity, M2M communications and a display, to enable rapid prototyping of a complete NFC-enabled end product.
ST’s NFC expansion board is based on the ams AS39230 boostedNFC analogue front end, and ST’s own ST54E system-in-package (incorporating the ST21NFCC controller and the ST33G1M2 Secure Element). Depending on application requirements, the board can be connected to various antenna sizes, ranging from 400 mm² supporting NFC Reader/Writer functionality down to ultra-tiny SMD antennas for Card Emulation-only functionality.
The circuit implemented in the new board provides NFC performance in conditions hostile to RF signals, for instance when operating close to or inside metal surfaces, or when transmitting through a very small antenna. Designers of IoT nodes and wearables, for instance, often have to enclose their devices in metal housings, or must accommodate an antenna inside an extremely small enclosure. The new expansion board gives them a ready-made NFC implementation that will achieve fast, reliable coupling with any standard NFC reader, such as smartphones, con-tactless payment terminals, transit system entry barriers and access control card readers.
The design implemented in the expansion board is also suitable for use in applications which re-quire worldwide certification, including for Common Criteria, EMVCo, GlobalPlatform, and Visa, Mastercard, Amex, and the People’s Bank of China (PBoC). It enables OEMs using an STM32 MCU to quickly implement a new design for a wearable device which can be used to pay for goods at contactless payment terminals, to emulate smart cards such as metro transit ticket cards, or to perform access control functions such as keyless entry to hotel rooms.
The RF performance of the NFC expansion board is due to the active load modulation method of boosting the NFC signal implemented in the AS39230. This produces an operating volume some 10 times larger than the passive load modulation method used in smart cards. At the same time, the AS39230 based system draws as low as 1µA average current in listening mode, thus draining far less power from the battery than conventional NFC solutions.
“The secure NFC expansion board’s RF performance is absolutely outstanding, and since it con-tains very few components it is remarkably easy for users of STM32 MCUs to implement. Because it is supported by a full suite of ST firmware for NFC applications, this board provides the quick-est, surest way to implement a successful new NFC design,” said Laurent Degauque, Secure Mi-crocontrollers Division Marketing Director of STMicroelectronics.
“No other NFC development system can operate completely reliably through an antenna as small as 100 mm², or even use the metal casing of the product as an antenna. The AS39230 in the NFC ex-pansion board can do this…with a space- or performance-constrained antenna,” said Mark Dickson, Business Line Director of Wireless Connectivity at ams.
STMicroelectronics; www.st.com/securewearable
ams; www.ams.com/NFC-HF-Booster/AS39230
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