ST25R200 datasheet(25/88 Pages) STMICROELECTRONICS

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IRQ when the latest measurement is above the upper limit: i/q_adc > i/q_ref + i/q_diff

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IRQ when the latest measurement is in between the upper and lower limit: i/q_ref – i/q_diff ≤ i/q_adc ≤ i/

q_ref + i/q_diff

•

IRQ when the latest measurement is below the lower limit: i/q_adc < i/q_ref - i/q_diff

In case the bits i_tdi_en<2:0> = 0, the I channel is not used during WU, and the same applies for the Q channel

when q_tdi_en<2:0> = 0.

5.13

Transparent mode

Standard or custom 13.56 MHz RFID reader protocols not supported by the ST25R200 framing system can be

implemented directly through the AFE via the transparent mode, where the framing is implemented on the host

side.

After sending the direct command transparent mode, the external host directly controls the transmission

modulator and gets the receiver output (control logic becomes “transparent”).

The transparent mode is entered on the rising edge of signal BSS after sending the command transparent mode.

Before executing the direct command transparent mode the transmitter and receiver must be turned on and the

AFE configured properly.

While in transparent mode the AFE is controlled directly through the SPI interface:

Table 4. Signals in transparent mode

Description

MOSI

Transmitter modulation - high is modulator on

SCLK

Enable reception (rx_on) - high enables reception chain and AGC

MISO

In case dis_corr=0, correlator data output (sum of I+Q)

In case dis_corr=1, output of receiver I reception chain (digitized subcarrier signal)

IRQ

In case dis_corr=0, correlator start signal (subcarrier detected)

In case dis_corr=1, output of receiver Q reception chain (digitized subcarrier signal)

ST25R200

Application information

DS13658 - Rev 2

page 25/88

ST25R200 Arkusz danych(PDF) 25 Page - STMicroelectronics