 In this module, we'll take a look at the internal functional blocks that make up the ST25R3916. We'll briefly describe how they operate and their primary uses. In a previous module, we describe the output circuit and how it functions. In addition to the output circuit and the serial communication to the IC, one must also apply a crystal, an analog, and digital voltage supplies. The external crystal supplies the input signal to the crystal oscillator. It operates with a 27.12 MHz crystal and provides timing for all the internal functions of the IC. In addition, it can also provide the clock signal for the external microcontrollers. Upon startup, an interrupt is generated when the oscillator is stable and the device is ready for operation. The RC oscillator is used for low power car detection and does not require the external crystal. The RC oscillator provides the clock signal to the wake-up timer. The ST25R3916 has four internal voltage regulators. These regulators supply the voltages needed for the analog circuitry, the digital circuitry, the RF transmitter, and the transmitter amplitude modulated level. These internal regulators have excellent power supply rejection ratios, which ensure very stable voltages are supplied to the internal circuitry. The transmitter block provides several key functions to the operation of the IC. First, it drives the antenna that produces the RF field that powers up the tag. It generates the modulation of the RF signal that provides communication to the tag. And finally, it generates the load modulation needed for card emulation. In front of the transmitter block is the TX encoding block. This block generates the start of frame, end of frame, and CRC and encodes them according to the desired RF mode and bitrate. The receiver's main function is to detect the tag modulation superimposed on the 13.56 MHz carrier signal. In order to do this, it can employ such functions as automatic gain control and squelch to clarify the incoming signal in noisy environments. It also decodes the incoming frames based upon the RF mode and bitrate selected. The start of frame, end of frame, CRC, and parity bits are removed leaving only the data payload. The amplitude and phase detector provides information about the phase and amplitude of the incoming signal with respect to the transmitted output. An A to D converter allows these parameters to be captured and displayed in the phase and amplitude display registers. The external field detector is used to determine if an external RF field is present at the antenna. This can be used as a wake-up mechanism when in peer-to-peer mode. The ST25R3916 has two 8-bit D to A converters used for the auto antenna tuning function. These DACs provide the input signal to the voltage-controlled caps, which are used to adjust the antenna matching. When used with the amplitude and phase detector, antenna tuning becomes automatic. There are two internal timers within the ST25R3916. The protocol timers reduce the overhead on the external microcontroller by internally providing the timing necessary for each of the reader-supported protocols. This improves the portability of the code since the timing function is generated by the reader and not the MCU. The wake-up timer is used for low-power mode and wake-up mode. The wake-up timer is unique because it does not require the crystal oscillator to be running, thus reducing the power consumption of the reader. The FIFO contains data to be transferred or the data received by the antenna from the tag. That is to say it contains the raw payload to be sent across the RF link. The FIFO on the ST25R3916 has been increased from 96 bytes to 512 bytes so they can hold one full frame of data. This lowers the overhead on the MCU as it will not have to service the reader as often. The ST25R3916 contains a total of 80 registers divided between register space A and B. The registers are either configuration registers that are read-write or display registers which store information about the state of the device. Display registers are read-only. The ST25R3916 offers both an I2C and an SPI interface. The interface selection is done via the I2C-enabled PIN. If this PIN is set to zero, the SPI interface will be active and one to this PIN will enable the I2C interface. These serial interfaces are activated by either commands from the MCU or the IRQ PIN. Thank you for viewing this presentation.