BLE - NFC

[Roei]

Hi,

I would like to ask a question regarding NFC connection.

When Im using my nrf52840 device to connect with a PC using NFC pad - the NFC triggers the nrf device to start advertising.

After that - a connection is established.

Can you please send me a link to the sequence of the connection? What exectly happens? (handshake etc)?

Thanks!

[Hung Bui]

Hi Roei, 
Please have a look at this example located in nRF5 SDK v17.0.2 : examples\ble_peripheral\experimental\ble_app_hrs_nfc_pairing

Documentation: 

https://infocenter.nordicsemi.com/topic/sdk_nrf5_v17.0.2/ble_sdk_app_hid_keyboard_pairing_nfc.html?cp=7_1_4_2_2_33

It does exactly what you want to do. 

[Roei]

Thanks! It helped me a lot.

In addition - can you please send me the sequence of the flow - including handshake, diffie hellman key exchange etc?

Thanks!

[Hung Bui]

Hi, 

What exactly you plan to do ? 

I would suggest just to leave the handshake and key exchange to the softdevice and the peer manager module. 
You can have a look at the message sequence charts here.

[Roei]

Hi,

I just want to understand the process, and I have some things that I don't understand.

When start advertising and connecting via mobile - I know that the mobile should recognize the device and send a connection request, and that the NRF device waits for connection requests while advertising.

But what happens when connection to a PC via NFC? After NRF device starts advertising - should the PC asks for a connection request?

Thanks!

[Hung Bui]

The NFC only act as a way to wake the device up and advertising. It's up to the central device (mobile phone or PC) to do what's next, for example send a connection request. 

[Roei]

Is that possible that the NFC pad contains a SW which sends the connection request or doing other stuff?

[Hung Bui]

No, the NFC can only transfer very limited amount of data with very low speed. I'm not aware of any way you can put software to do anything on the NFC peripheral.