AN3985 datasheet(23/105 Pages) STMICROELECTRONICS

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AN3985

CR95HF low level layer

Doc ID 022255 Rev 2

23/105

CR95HF_Sleep function

This function sends a Sleep command to CR95HF and turns the sleep state on.

CR95HF_TagDetecting function

This function sends a Tag detecting command to CR95HF. The CR95HF turns in a low

power mode and periodically checks if a contactless tag is in the operating value. In this last

case, the CR95HF will wake-up by itself.

Table 26.

CR95HF_Sleep function description

Prototype

u8 CR95HF_Sleep (CR95HF_Idle_Config* Idle_Config);

Input parameter

WakeUpSource: the source of wake-up for CR95HF(1)

e.g.: for a wake-up by a pulse on SPI_NSS pad, use CR95HF_IDLE_WAKEUP_SPIN_SS value. For a

wake- up by a pulse on IRQ_IN pad, use CR95HF_IDLE_WAKEUP_IRQ_in value.

Output parameter

Idle_Config: pointer on the structure which contains data about some idle

parameters to update

Return parameter

CR95HF_SUCCESS_CODE: The command is successful.

Table 27.

CR95HF_TagDetecting function description

Prototype

u8 CR95HF_TagDetecting (const u8 WakeUpSource, const u8

WUperiod,const u8 DACdataL, const u8 DACdataH,

CR95HF_Idle_Config* Idle_Config);

Input parameter

WakeUpSource: other source of wake-up for CR95HF than tag detecting (1)

LFOfreq: LFO frequency (2bits) (00 : 32 kHz 01 : 16 kHz 10 : 8 kHz 11 : 4 kHz)

WUperiod: tinactive = time between two bursts = ( Wuperiod +1 )* 256 / LFOfreq

DACdataL: low threshold of tag detecting

DACdataH: high threshold of tag detecting

e.g.: for a wake-up by a pulse on SPI_NSS pad, use CR95HF_IDLE_WAKEUP_SPINSS value. For a

wake-up by a pulse on IRQ_IN pad, use CR95HF_IDLE_WAKEUP_IRQ_in value.

Output parameter

Idle_Config: pointer on the structure which contains data about some idle

parameters to update

Return parameter

CR95HF_SUCCESS_CODE: The command is successful.

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