Circuit design and structure of universal card reader based on NFC

 EM4094 is an integrated transceiver chip that can be used to build an analog front-end module for RFID readers. The chip's data transmission and reception links allow transmission and decoding of any communication protocol, so the EM4094 supports all EM's 13.56MHz transceiver chips, ISO15693, ISO14443 A&B, and Sony Felica protocols. With appropriate settings, the EM4094 can even communicate with NFC devices. This article will explain through a series of steps how a hardware engineer should integrate and utilize the EM4094 RFID reader circuit.

Typical application circuit configuration

Card reader structure

Basically, the analog front-end module is one of the components of the RFID reader. It is responsible for encoding/decoding data and driving the RFID reader antenna with appropriate power. The analog front-end module itself is driven by a microcontroller. The microcontroller is responsible for managing the frame decoding tasks of different protocols, as well as the communication interface (serial interface, USB interface or Ethernet interface) with the PC or other background control device. Some IC vendors offer chips that integrate an analog front end and a microcontroller. In many cases, the microcontroller or integrated memory space is either more than needed or not sufficient, and stand-alone modules allow manufacturers to select the microcontroller and memory capacity that best suits their design requirements. Of course, the manufacturer will depend on the desired functionality. Make your decision based on factors such as level, read range, and power requirements. Since there are already chips like the EM4094 that provide complete flexibility, below we will discuss how to integrate this card reader chip in an actual card reader. Figure 1 shows a typical application circuit configuration.