ST95HF datasheet(26/93 Pages) STMICROELECTRONICS

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Commands

ST95HF

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DocID025630 Rev 4

5.5

Pollfield command (0x03) description

This command returns the current value of the FieldDet flag.

The result of this command depends on the protocol selected. If we select a Reader mode

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

Table 14. POLLFIELD command description

Direction

Data

Comments

Example

Host to

ST95HF

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):

: Wait for RF field

appearance

: Wait for RF field

disappearance

<Presc>

Timer prescaler (Optional)

<Timer>

Timer time-out (Optional)

ST95HF to

Host

Result code

<<<0x0000 or 0x000100

(No RF

field detected) or 0x000101 (RF field

detected)

Length of data

, if FieldDet is set.

Otherwise, 00.

Table 15. Response for <POLLFIELD> command

Function

Explanation

Response example

Comments

Pollfield

Response

01 or 00

This command returns the

current state of the RF

field.

<<<0x0000 or

0x000100

(No RF field

detected) or 0x000101

(RF field detected)

Result code

Length of data field

Bits [7:1]: RFU

Bit 0: Field detected (if set)

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