I'm experimenting problems between my NFC reader and my NFC Smarthphone (I am using Host-based Card Emulation). The problem is the following... My android application is able to receive the APDU to select the AID and I am able to return a result for the reader.
After that, I try to send a specific command to reader and get the response. I receive the call in my override method processCommandApdu and when It return the result, I receive an event in onDeactivated method which reason is DEACTIVATION_LINK_LOSS (my phone is very close of the reader).
Have you any idea about it?
Background: Commands are always initiated by the terminal. Your processCommandApdu() method is there to take that command the terminal sends, and then send back a response in the format that the terminal requires. It depends on what type of application you are creating and what kind of terminal you are using for development.
Answer: [DEACTIVATION_LINK_LOSS] happens when the terminal is done sending commands out and the NFC connection between the device and the terminal is terminated. This has nothing to do with the fact that your phone is close or not, this only has to do with the fact that the terminal is done with it's communication and the connection between the device is no longer there.
Documentation: https://developer.android.com/reference/android/nfc/cardemulation/HostApduService.html#DEACTIVATION_LINK_LOSS