ST25R95 datasheet(19/61 Pages) STMICROELECTRONICS

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5.5

Pollfield command (0x03) description

This command can be used to detect the presence/absence of an HF field by monitoring the field detector

(FieldDet) flag. It can be used as well to wait for HF field appearance or disappearance until a defined timeout

expires. The answer to the PollField command is the value of the FieldDet flag.

Table 14. Pollfield command description

Direction

Data

Comments

Example

Host to

ST25R95

Command code

>>>0x0300 Check if RF Field is ON or OFF

>>> 0x0303010FFF - Wait for RF Field appearance for

(16*256)/13.56 µs

Flags, Presc and Timer parameters are optional. They must

be specidfied if the application has to wait for RF field appearance

or disappearance.

The time to wait is (

Presc+1)*(Timer+1)/13.56 µs.

<Len>

Length of data

<Flags>

RF field presence

(Optional):

01: Wait for RF field

appearance

00: Wait for RF field

disappearance

<Presc>

Timer prescaler

(Optional)

<Timer>

Timer time-out

(Optional)

ST25R95 to

Host

Result code

<<<0x0000 No RF field detected

Length of data

ST25R95 to

Host

Result code

<<<0x0000 or 0x000100 (No RF field detected) or

0x000101 (RF field detected)

Length of data

[7:1]: RFU

0: No field detect

1: Field detect

ST25R95 to

Host

Error code

<<<0x8200 Invalid command length

Length of data

The result of this command depends on the protocol selected. If a reader mode protocol is selected, the flag

FieldDet is set to ‘1’ because the RF field is turned ON by the reader.

ST25R95

Pollfield command (0x03) description

DS12807 - Rev 4

page 19/61

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