NFC Extend Click is NFC tag interface device with possibility of using any shape and size external antenna, offering 16 Kbit of electrically erasable programmable memory (EEPROM). This Click board™ offer two communication interfaces. The first one is an I2C serial link and can be operated from a DC power supply. The second one is a RF link activated when Click Board™ act as a contactless memory powered by the received carrier electromagnetic wave. It is perfectly suited for using in wide variety of applications, such as NFC enabled business cards, stickers, wristbands, key fobs, pens, movie passes, hang tags, medication bottles, and many more.
NFC Extend Click board™ is supported by a mikroSDK compliant library, which includes functions that simplify software development.
For any functionality NFC Extend Click has to be used with an NFC antenna.
The active NFC tag component on NFC Extend Click is the ST25DV16K - the compact NFC tag IC from STMicroelectronics. The Click board™ itself has a reasonably small number of components because most of the interface and EEPROM memory circuitry is already integrated on the ST25DV16K IC. The I2C / SMBus compatible serial interface lines, along with the GPO pin, which also works in the open drain configuration, are pulled up by the on-board resistors. The 2-Wire lines are routed to the respective I2C lines of the mikroBUS™ (SCK and SDA), while the GPO pin of the main IC is routed to the INT pin of the mikroBUS™.
Depending on the application requirements various shapes and sizes of 13.56 MHz external antenna can be used by connecting them to CN1 (male U.FL) connector.
The ST25DV16K uses the I2C/SMBus compatible communication interface, offering a fast transfer mode (FTM), to achieve a fast link between RF and contact worlds, via a 256 byte buffer called Mailbox. This mailbox dynamic buffer of 256 byte can be filled or emptied via either RF or I2C.
There is also the INT pin available, which indicates incoming event to the contact side, like RF Field changes, RF activity in progress, RF writing completion or Mailbox message availability. The built in energy harvesting element can deliver µW of power when external conditions make it possible. The integrated RF management allows the NFC Extend Click to ignore RF requests.
All these features can be programmed by setting static and/or dynamic registers of the ST25DV16K. ST25DV16K can be partially customized using configuration registers located in the E2 system area. More information about all the registers can be found in the ST25DV16K datasheet. However, provided library contains functions that simplify the use of the NFC Extend Click. The included application example demonstrates their functionality and it can be used as a reference for custom design.
The Click board™ can be supplied and interfaced with both 3.3V and 5V without the need for any external components. The onboard SMD jumper labeled as VCC SEL allows voltage selection for interfacing with both 3.3V and 5V MCUs.
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