ST25R3911B datasheet(36/116 Pages) STMICROELECTRONICS

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Table 13. Test Access Register - tana signal selection of CSI and CSO pins

Tana_

Pin CSI

Pin CSO

Comments

3 2 1 0 Type

Functionality

Type

Functionality

0 0 0 1

Analog output of AM channel (before

digitizer)

Digital output of AM channel (after

digitizer)

Normal operation

0 0 1 0

Analog output of PM channel (before

digitizer)

Digital output of PM channel (after

digitizer)

Normal operation

0 0 1 1

Analog output of AM channel (before

digitizer)

Analog output of PM channel (before

digitizer)

Normal operation

0 1 0 0

Digital output of AM channel (after

digitizer)

Digital output of PM channel (after

digitizer)

Normal operation

0 1 0 1

Analog signal after first stage

Analog signal after second stage

Normal operation:

•

PM channel if enabled

•

AM if PM is not enabled

1 0 0 1

Channel selection from logic

Collision Avoidance detector output

Collision Avoidance detectors

are enabled

1 0 1 0

Digital TX modulation signal

Select PM

Analog part of channel selection

0 0 0 1

Analog output of AM channel (before

digitizer)

Digital output of AM channel (after

digitizer)

Normal operation

1.2.16

Power-up sequence

At power-up, the ST25R3911B enters the Power-down mode. The content of all registers is set to the default

state.

The microcontroller, after a power-up, must correctly configure the two IO configuration registers. The

content of these two registers defines operation options related to hardware (power supply mode, Xtal type,

use of MCU_CLK clock, antenna operation mode).

Configure the regulators. It is recommended to use direct command Adjust Regulators to improve the

system PSRR.

When implementing the LC tank tuning, send the direct command Calibrate Antenna.

When using the AM modulation (ISO-14443B for example), set the modulation depth in the AM modulation

depth control register and send the command Calibrate Modulation Depth.

The ST25R3911B is now ready to operate.

1.2.17

Reader operation

To begin with, the operation mode and data rate have to be configured by writing the Mode definition register and

Bit rate definition registerBit Rate Definition register. Additionally, the receiver and transmitter operation options

related to operation mode have to be defined. This is done automatically by sending the direct command Analog

Preset. If more options are required apart from those defined by Analog Preset, then such options must be

additionally set by writing the appropriate registers.

Next, the Ready mode has to be entered by setting the bit en of the Operation control register. In this mode the

oscillator is started and the regulators are enabled. When the oscillator operation is stable, an interrupt is sent.

Before sending any command to a transponder, the transmitter and receiver have to be enabled by setting the bits

rx_en and tx_en. RFID protocols usually require that the reader field is turned on for a while before sending the

first command (5 ms for ISO14443). General purpose timer can be used to measure this time interval.

If REQA or WUPA have to be sent, this is simply done by sending the appropriate direct command, otherwise the

following sequence has to be followed:

Send the direct command Clear

Define the number of transmitted bytes in the Number of transmitted bytes register 1 and Number of

transmitted bytes register 2.

Write the bytes to be transmitted in the FIFO

Send the direct command Transmit With CRC or Transmit Without CRC (whichever is appropriate)

When all the data is transmitted an interrupt is sent to inform the microcontroller that the transmission is

finished (IRQ due to end of transmission)

ST25R3911B

Application information

DS11793 - Rev 6

page 36/116

ST25R3911B Datasheet(PDF) 36 Page - STMicroelectronics

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