NFC SNEP and LLCP protocols between android 4.3 and pn532

Question

Does anyone know where to find the android 4.3 nfc service source code?

I recently bought the NFC shield from seeedstudio and downloaded its library. The library works awesome with a samsung galaxy s3 on android 4.1.2 . However when using galaxy s4 and galaxy note 2 on android 4.3 , the communication just work the first time. After the first time the nfc controller gets stuck and does not read from the pn532 .

I wanted to see the source code to see whats the difference between the two services and try to change the seeedstudio library or so. I also notice that the signal strength plays an important role, when i place the galaxy note 2 antenna in the same exact position of the pn532 antenna then the failure does not occur. Maybe the strength signal matters because between the two devices the communication never fails.

I would appreciate any help on how to get the Samsung SNEP-LLCP protocol description. Or if somebody could point me to a NFC library already tested with galaxy s4 and galaxy note 2 would be awesome.

Answer 1

I already notice the reason that was causing the failure in galaxy s4 and galaxy note 2. An unexpected service coming from the phone was asking for connection in the middle of the protocol. Since the original seeedstudio library did not validated this case the whole protocol failed. I fix the llcp protocol flow bypassing this service request and now it works properly. For more details see the next link: llcp-dep p2p discovery and connections