ST25R95 datasheet(28/61 Pages) STMICROELECTRONICS

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5.9

Idle command (0x07) description

This command switches the ST25R95 into low power consumption mode and defines the way to return to Ready

state.

The Result code contains the Wake-up flag register value indicating to the application the wake-up event that

caused the device to exit WFE mode.

Caution:

In low power consumption mode the device does not support SPI poll mechanism. Application has to

rely on IRQ_OUT before reading the answer to the Idle command.

Table 24. Idle command description

Direction

Data

Comments

Example

Host to

ST25R95

Command code

Example of switch from Active mode to

Hibernate state:

>>>0x07 0E 08 04 00 04 00

18 00 00 00 00 00 00 00 00

Example of switch from Active to WFE

mode (wake-up by low pulse on IRQ_IN

pin):

>>>0x07 0E 08 01 00 38 00

18 00 00 60 00 00 00 00 00

Example of switch from Active to WFE

mode (wake-up by low pulse on SPI_SS

pin):

>>>0x07 0E 10 01 00 38 00

18 00 00 60 00 00 00 00 00

Example of wake-up by Timeout (7

seconds):

Duration before Timeout = 256 * tL * (WU

period + 2) * (MaxSleep + 1)

>>>0x07 0E 01 21 00 38 00

18 00 60 60 00 00 00 00 08

Example of switch from Active to Tag

detector mode (wake-up by tag detection

or low pulse on IRQ_IN pin) (32 kHz,

inactivity duration = 272 ms, DAC

oscillator = 3 ms, Swing = 63 pulses of

13.56 MHz):

>>>0x07 0E 0A 21 00 79 01

18 00 20 60 60 64 74 3F 08

Example of a basic Idle command used

during the Tag detection Calibration

process:

>>>0x07 0E 03 A1 00 F8 01

18 00 20 60 60 00 xx 3F 01

where

xx is the DacDataH value.

Length of data

Specifies authorized wake-up sources and the LFO

frequency

EnterCtrlL

Settings to enter WFE mode

EnterCtrlH

WUCtrlL

Settings to wake-up from WFE mode

WUCtrlH

LeaveCtrlL

Settings to leave WFE mode (default value = 0x1800)

LeaveCtrlH

Period of time between two tag detection bursts. Also

used to specify the duration before Timeout.

Defines the wait time for HFO to stabilize:

<OscStart> * tL

(Default value = 0x60)

Defines the wait time for DAC to stabilize:

<DacStart> * tL

(Default value = 0x60)

Lower compare value for tag detection (1) .

This value must be set to

0x00 during tag detection

calibration.

Higher compare value for tag detection (1).

This is a variable used during tag detection calibration.

Number of swings HF during tag detection (Default

value = 0x3F)

Max. number of tag detection trials before Timeout (1).

This value must be set to

0x01 during tag detection

calibration.

Also used to specify duration before Timeout.

MaxSleep must be:

0x00 < MaxSleep < 0x1F

ST25R95

Idle command (0x07) description

DS12807 - Rev 4

page 28/61

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