ST25R3910 datasheet(35/65 Pages) STMICROELECTRONICS

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ST25R3910

Functional overview

the direct command Transparent Mode the Transmitter and Receiver have to be turned on,

and the AFE has to be configured properly.

While the ST25R3910 is in the Transparent mode the AFE is controlled directly through the

SPI interface:

•

The Transmitter modulation is controlled by pin SDATAI (high is modulator on)

•

Signal rx_on is controlled by pin SCLK (high enables RSSI and AGC)

•

The Receiver output is sent to pin SDATAO

By controlling the rx_on advanced Receiver features like the RSSI and AGC can be used.

Configuration bits related to the ISO mode, framing and FIFO are meaningless in

Transparent mode, but all other configuration bits are respected.

The transmitter modulation type used (OOK or AM) is defined by bit am of the Configuration

The direct command Calibrate Modulation Depth supports modulation depths up to 30%,

deeper AM modulation is possible by writing the Antenna Driver AM Modulated Level

Definition Register.

The receiver filters support the subcarrier frequencies from 212 to 848 kHz. The filter

characteristics can be configured via bits fs2 to fs0 in the Receiver Configuration Register.

Active receive – Use in ISO-14443B Anticollision

In some cases it is useful to know that a response from a tag is being received. This

information is provided by bit rx_act in the FIFO Status Register. This bit is set to 1 when the

start of the tag message is detected, and stays high until the end of reception.

This information can be used to speed up the ISO-14443B anticollision procedure when

more slots are used. When there is no message in a certain slot, the reader does not have

to wait for the time a complete ATQB takes before sending the next Slot-MARKER

command, but it can send the next Slot-MARKER as soon as it is clear that there is no

answer in that particular slot. The microcontroller can obtain this info by reading the rx_act

flag at the time the receiver should already be processing the ATQB message. In case

rx_act flag is set to one the receiver is processing a message and the microcontroller has to

wait for the end of receive interrupt, in opposite case when the rx_act flag is set to zero there

is no ATQB message in that particular slot and the next Slot-MARKER command can be

sent immediately.

ISO-14443B, reduction of TR0 and TR1 and suppression of EOF/SOF in PICC

response

The ISO-14443-3 standard, chapter 7.10.3 Coding of Param 1 defines possibility to reduce

the TR0 and TR1 and suppress the EOF/SOF in PICC response.

Note:

The ST25R3910 Receiver and Framing blocks do not support the reduction of TR0 and TR1

and suppression of EOF/SOF. If default settings of these parameters are changed, the

framing block will not be able to decode the PICC response.

Test pins

Pins TEST and TIO are used to test the ST25R3910. Pin TEST is a digital pin with pull

down, it is used to enter the test mode, pin TIO is used in test mode as a digital IO, in normal

mode it is in tristate. It is recommended to connect pin TEST to VSS and to leave pin TIO

open.

ST25R3910 Datasheet(PDF) 35 Page - STMicroelectronics

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