Can CR95HF inform external MCU by itself when some TAG/Device is detected?

MIdzk · ‎2019-06-26

Hello!

I have question about CR95HF (with SPI interface selected, MODE: Reader).

Is it possible that chip can inform HOST/external MCU (STM32F4) when some TAG/Device shows up in RF field range?

There is IRQ_OUT pin, but it's only informing when some data to be received by HOST is ready.

So I assume HOST has to poll device with SendRcv Command (0x04) and checks respond if it is not an ERROR_CODE (0x8700)?

Also there something like "Wake-up by Tag Detection". Is this something I am asking for?

Thanks!

Brian TIDAL · ‎2019-06-27

Hi Michal,

For new development, ST recommends to use the ST25R95 rather than CR95HF.

Both ST25R95 and CR95HF supports a Tag Detector (see §3.1 in ST25R95 Datasheet). Tag detector is a state where ST25R95/CR95HF is able to detect an RF event, a wake-up will occur when a tag sufficiently modifies the antenna load and is detected by the ST25R95/CR95HF.

The Idle command can be used to enter Tag Detector mode (see §5.9 in ST25R95 Datasheet). When an RF event occurs (e.g. tag in the RF field), the ST25R95/CR95HF exits the Tag detector state and the Idle response indicates the wake up source. Application has to rely on IRQ_OUT before reading the answer to the Idle command (while in low power mode, the SPI polling mechanism is not supported). Once a tag has been detected, the application has to use ProtocolSelect and SendRecv to perform technology detection, anti-collision and activation.

Before using the Tag detector, a calibration is needed.

See Application Note AN3433 for further details on Tag Detection on ST25R95/CR95HF.

The tag detection feature is available in the X-CUBE-NFC3 v2.0.0 software expansion package running on X-NUCLEO-NCF03A1 expansion board for ST25R95/CR95HF. This package includes a Polling demo application: when pressing the user button of the NUCLEO board, the wakeup mode is toggled. In this mode, once a RF event has been detected (i.e. tag in the field) , the device returns in active mode and the application polls for the various technologies, displays the UID and returns in wakeup mode. Note: the calibration is automatically performed in the X-CUBE-NFC3 software expansion package

Welcome to X-NUCLEO-NFC03A1 (SPI Interface)
RFAL initialization succeeded..
Going to Wakeup mode. (<-- message displayed when pressing the User Button)
ISO15693/NFC-V card found. UID: E0022400026AE452

Rgds

BT

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View solution in original post

Brian TIDAL · ‎2019-06-27

Hi Michal,

For new development, ST recommends to use the ST25R95 rather than CR95HF.

Both ST25R95 and CR95HF supports a Tag Detector (see §3.1 in ST25R95 Datasheet). Tag detector is a state where ST25R95/CR95HF is able to detect an RF event, a wake-up will occur when a tag sufficiently modifies the antenna load and is detected by the ST25R95/CR95HF.

The Idle command can be used to enter Tag Detector mode (see §5.9 in ST25R95 Datasheet). When an RF event occurs (e.g. tag in the RF field), the ST25R95/CR95HF exits the Tag detector state and the Idle response indicates the wake up source. Application has to rely on IRQ_OUT before reading the answer to the Idle command (while in low power mode, the SPI polling mechanism is not supported). Once a tag has been detected, the application has to use ProtocolSelect and SendRecv to perform technology detection, anti-collision and activation.

Before using the Tag detector, a calibration is needed.

See Application Note AN3433 for further details on Tag Detection on ST25R95/CR95HF.

The tag detection feature is available in the X-CUBE-NFC3 v2.0.0 software expansion package running on X-NUCLEO-NCF03A1 expansion board for ST25R95/CR95HF. This package includes a Polling demo application: when pressing the user button of the NUCLEO board, the wakeup mode is toggled. In this mode, once a RF event has been detected (i.e. tag in the field) , the device returns in active mode and the application polls for the various technologies, displays the UID and returns in wakeup mode. Note: the calibration is automatically performed in the X-CUBE-NFC3 software expansion package

Welcome to X-NUCLEO-NFC03A1 (SPI Interface)
RFAL initialization succeeded..
Going to Wakeup mode. (<-- message displayed when pressing the User Button)
ISO15693/NFC-V card found. UID: E0022400026AE452

Rgds

BT

In order to give better visibility on the answered topics, please click on Accept as Solution on the reply which solved your issue or answered your question.