Rev. 1.00
206
September 11, 2018
Rev. 1.00
207
September 11, 2018
HT45F4050
A/D NFC Flash MCU
HT45F4050
A/D NFC Flash MCU
Application Descriptions
The Near Field Communication, NFC, is a wireless high frequency communication technology,
supporting data exchange within a distance of less than 10cm. Compared with IR, Bluetooth and
other such like technologies, communication connection for NFC can be easily implemented only by
device touching, wihout requiring beforehand device match or APP opening, resulting in faster data
link.
The HT45F4050 acts as a passive NFC tag which can only be accessed by other NFC active devices.
NFC tags are usually used in advertisement, small amount of data storage and data transmission
to the NFC active devices, etc. As the HT45F4050 includes an integrated MCU, it can be used for
applications such as smart meters, smart home appliances, NFC data loggers, etc.
NFC Operating Principle
Briefly speaking, NFC communication is a technology uses radio frequency signals to transmit
data wirelessly and then uses the back-end application system to implement identification. An NFC
system is mainly composed of electronic tag, reader and system application software. The reader
antenna emits a range of radio waves, when the tag is within the radio range, the reader can read the
information stored in the tag.
The function of the NFC system coil circuit is divided into two parts, one is to use radio frequency
signals to generate power, the other is to receive and transmit data by means of signal modulation.
Generally the reader will first emit a radio scan signal with a frequency of 13.56MHz. If a passive
NFC tag presents within the scan range, it can receive the scan signal. Then the tag will implement
signal decoding. If the signal decoding is correct, the tag will change the electromagnetic field using
signal modulation to notify the reader its presence.
Because of the coupling between the HT45F4050 antenna and reader antenna, the passive lising
device (tag) can also act on the active querying device (reader). The impedence change on the tag
antenna will directly affect the voltage amplitude or phase change on the reader antenna, which can
be detected by the reader. This is the load modulation technology. The HT45F4050 is a NFC Type A
tag which uses the Manchester coding method.
Hardware Block Diagram
To demonstrate the functionality of the HT45F4050 application system, Holtek has developed
an NFC data logger demo board. This board (tag) including hardware sensors, an SPI Flash data
memory and non-contract communication interface, supports the 13.56MHz NFC communication
technology. The hardware sensors include a temperature sensor (833ET-2) and a humidity sensor
(DHT12).