Replace a Power-On Switch with NFC

[vince1]

We make a credit-card size Data Acquisition device which transfers data over Bluetooth to our iOS or Android App running on a phone which can be optionally attached to the phone.  The device has a PIC Microcontroller with an I2C interface and is powered by a 700 mAh Li-ion battery.

We want to replace or supplement the device's Power Button so the device can be powered-on with an NFC tap to the phone that is running our App.  We can add an NFC Connected Tag with loop antenna to do this.

Do you have a reference design showing how to do this?

Is there a demo board (perhaps with Arduino) that supports Power-on Reset using an NFC connected tag?

[vince1]

Eduardo,

Making progress.  I use Energy Harvesting enabled during boot for this proof of concept, though likely we will make a custom App and use Energy Harvesting by session registers if the project moves forward.

By the way, I have the OM13074UL “LPCXpresso board (V2) for LPC1” on backorder with the NXP Store.  Not sure why this Development board is out-of-stock.

Vince

[EduardoZamora]

Hello @vince1

Hope you are doing well.

NTAG 5 family from our Connected NFC Tags portfolio include Energy Harvesting feature, which provides the capability to harvest energy from the RF field. This feature can be used to supply external circuits or devices with enough energy to operate. Perhaps this feature could be useful for your development.

If you are interested in NTAG 5 Energy Harvesting, please refer to NTAG 5 - How to use energy harvesting; here you will find some considerations, configurations, antenna recommendations and relevant links.

Regards,
Eduardo.

[vince1]

Eduardo,

I enable Energy Harvesting using session registers using the procedure in Section 4.1 of https://www.nxp.com/docs/en/application-note/AN12365.pdf?_gl=1*yitg9y*_ga*MTI1NjkyMTg2Ni4xNzE4MTM5Nz....

But the EH_CONFIG_REG session register does not change and there is no Energy Harvesting.

Do you have any suggestions?  Here are the Commands and Responses:

1. VCD triggers current detection by by writing to EH_CONFIG_REG session register

(A7h) → EH_TRIGGER (Bit3) set to 1b

Command and Response to Trigger Current Detection

(A7h) → EH_TRIGGER (Bit3) set to 1b (Note: 0x08 = 0000 1000)

Command: 21 A7 08 00 00 00

Response: OK

1. VCD polls EH_CONFIG_REG (A7h) until the available field strength is sufficient →

EH_LOAD_OK (Bit7) equal to 1b

Commands and Responses to Read EH_CONFIG Reg A7

Command: 20 A7

Response: 08 00 00 00

Command: 20 A7

Response: 08 00 00 00

Command: 20 A7

Response: 08 00 00 00

Command: 20 A7

Response: 08 00 00 00

1. VCD enables the energy harvesting by writing to EH_CONFIG_REG session register

(A7h) → EH_ENABLE (Bit0) set to 1b and EH_TRIGGER (Bit3) set to 1b (Note: 0x33 = 0011 0011)

Enable Energy Harvesting

Command: 21 A7 33 00 00 00

Response: OK

1. VCD polls STATUS1_REG (A0h) until VCC ramps up → VCC_BOOT_OK (Bit7) equal

to 1b

Commands and Responses to Read EH_CONFIG Reg A7

Command: 20 A7

Response: 33 00 00 00

Command: 20 A7

Response: 33 00 00 00

Command: 20 A7

Response: 33 00 00 00

Command: 20 A7

Response: 33 00 00 00

Command: 20 A7

Response: 33 00 00 00

Command: 20 A7

Response: 33 00 00 00

Regards,

Vince

[EduardoZamora]

Hello,

Could you please try enabling energy harvesting by following the procedure shown in NTAG 5 - How to use energy harvesting, Section 4.2?

After this, please let me know your findings.

Regards,
Eduardo.

[vince1]

Eduardo,

Enabling Energy Harvesting during boot "using Configuration Registers" (Section 4.2 in AN12365) works!  See attached photos.

Enabling Energy Harvesting "using Session Registers" (Section 4.1 in AN12365) does not work, as described in my previous post).  The tag produces no EH.  This is where I need help.

Vince

[EduardoZamora]

Hi,

Please, consider that changes to session registers take effect immediately, but only for the current communication session. After POR, the session registers values will again contain the
configuration register values as before.

If the RF field is off (device loses power), session registers values may be lost.

Regards,
Eduardo.

[vince1]

Eduardo,

Yes, I understand the Session Registers persist only for the current communciation session.   The EH_CONFIG_REG session register does not change (during the communication session) and there is no Energy Harvesting.

Do you have a working EH example using session registers to share?

Here are the Commands and Responses:

1. VCD triggers current detection by by writing to EH_CONFIG_REG session register

(A7h) → EH_TRIGGER (Bit3) set to 1b

Command and Response to Trigger Current Detection

(A7h) → EH_TRIGGER (Bit3) set to 1b (Note: 0x08 = 0000 1000)

Command: 21 A7 08 00 00 00

Response: OK

1. VCD polls EH_CONFIG_REG (A7h) until the available field strength is sufficient →

EH_LOAD_OK (Bit7) equal to 1b

Commands and Responses to Read EH_CONFIG Reg A7

Command: 20 A7

Response: 08 00 00 00

Command: 20 A7

Response: 08 00 00 00

Command: 20 A7

Response: 08 00 00 00

Command: 20 A7

Response: 08 00 00 00

1. VCD enables the energy harvesting by writing to EH_CONFIG_REG session register

(A7h) → EH_ENABLE (Bit0) set to 1b and EH_TRIGGER (Bit3) set to 1b (Note: 0x33 = 0011 0011)

Enable Energy Harvesting

Command: 21 A7 33 00 00 00

Response: OK

1. VCD polls STATUS1_REG (A0h) until VCC ramps up → VCC_BOOT_OK (Bit7) equal

to 1b

Commands and Responses to Read EH_CONFIG Reg A7

Command: 20 A7

Response: 33 00 00 00

Command: 20 A7

Response: 33 00 00 00

Command: 20 A7

Response: 33 00 00 00

Command: 20 A7

Response: 33 00 00 00

Command: 20 A7

Response: 33 00 00 00

Command: 20 A7

Response: 33 00 00 00

[EduardoZamora]

Hi,

I tested the procedure by using session registers method as described in NTAG 5 - How to use energy harvesting, Section 4.1, PEGODA Reader and RFIDDiscover, and it is working as expected:

Regards,
Eduardo.

[vince1]

Eduardo.

Thanks!  I reproduced your results using RFIDDiscover v5.5.0.0 / Pegoda 3.  I have some debug on my PoC to do.

Vince

[vince1]

Eduardo

Thanks for your suggestions / references.

The NTAG 5 link can be a good fit as Energy Harvesting is necessary to wakeup our Data Aquisition device.

I have the NXP OM2NTP5332 NTAG 5 development kit, but not the OM13071UL LPCXpresso board for the USB-I2C bridge which is need for the NTAG 5 I2C Cockpit application (Section 3.1.1 USB-I2C bridge in UM11406).  The OM13071UL is back ordered on the NXP Website and from your Distributors.  Is there an alternative?

Vince

[EduardoZamora]

Hi,

The USB-I2C implementation can be ported to another environment using the instructions provided in UM11406, Chapter 5 Porting to other hardware.

Regards,
Eduardo.

[vince1]

Eduardo,

Thanks for your support.

I attempted unsuccessfully to port the USB-I2C implementation to the LPCXpresso824-MAX Evaluation board "OM13071" using the instructions provided in UM11406, Chapter 5 to implement the USB-I2C bridge, with the NTAG 5 development kit "OM2NTX5332" mounted, to be used NTAG 5 I2C Cockpit v1.1.

Please advise if the USB-I2C bridge configuration instructions are available specific for the OM13071.

Regards,

Vince

[EduardoZamora]

Hi,

My apologies, since the NTAG 5 I2C Cockpit tool interfaces to USB-I2C bridge via VCOM port, a device supporting USB may be required to act as bridge.

Regards,
Eduardo.

[vince1]

Eduardo,

Thanks for the confirmation.

Fortunately I got the PNEV5180BM "PN5180 Development Board" to connect with NXP NFC 5 Cockpit.  So I can continue.

Vince