ST25R95 datasheet(42/61 Pages) STMICROELECTRONICS

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Table 40. state when behaving as ISO/IEC 14443-A tag

Value

AC state

0x00

Idle

0x01

ReadyA

0x04

Active

0x80

Halt

0x81

ReadyA*

0x84

Active*

The AC filter command activates or deactivates an anti-collision filter for ISO/IEC 14443A card protocol. This

command also forces or indicates the card emulator state.

If the AC filter is not activated, all received commands are stored in the ST25R95 buffer before being read by the

external microcontroller.

If the AC filter is activated, internal firmware will try to interpret the commands sent by the reader itself and

perform an anti-collision sequence. The internal state machine of the AC filter also handles the SLP_REQ

command and changes the AC state accordingly, in order to have the proper handling of the SENS_REQ and

ALL_REQ commands in the various state. Non-interpreted commands are stored in the ST25R95 buffer before

being read by the external microcontroller to perform card emulation.

The ST25R95 is able to interpret and respond to the commands listed in the table below. The device remains in

Listening mode after executing these commands.

The ST25R95 handles those commands as long as the AC filter is active.

Table 41. Commands to which the device is able to react

Command

Code

Definition

SENS_REQ

26 (7-bit)

Sense request

ALL_REQ

52 (7-bit)

WakeUp All request

SDD_REQ

93, 95, 97

Single device detection request

SEL_REQ

9370, 9570, 9770

Select request

SLP_REQ

5000

Sleep request

5.13

Echo command (0x55) description

The Echo command verifies the possibility of communication between a Host and the ST25R95. The ST25R95

will exit the listen mode upon reception of an echo command. This can be used to stop listen mode (see

Section 5.7 Listen command (0x05) description).

Table 42. Echo command description

Direction

Data

Comments

Example

Host to ST25R95

0x55

Command code

ST25R95 to Host

0x55

Code response

>>> 0x55: Sends an Echo command

<<< 0x55: Response to an Echo command

ST25R95

Echo command (0x55) description

DS12807 - Rev 4

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