Writing unencrypted binary data on a Mifare Desfire V1 4096byte

[HD]

Hello community, I try to store some measurement data on a Mifare Desfire V1. I was able to reduce my measurement data to 500 points consisting out of 2 values (1000 Values total). By storing them as 32 bit (4 byte) double precision numbers I am at 4000 byte required space. I am actually trying to find out how to write these 4000 byte of binary data to my Mifare Desfire V1 4096. I found out, that I am able to get into read and write access by using the APDU commands for: - Detection of NDEF Message (00 A4 04 00 07 D2 76 00 00 B5 01 01 00) - Capability Container Select - NDEF Select Command - Read Binary of NLEN field - Write Data in NDEF file (I actually use an android phone and app to perform these APDU commands) but unfortunately all this progress I made did not bring the possiblity to do what I want. I dont need any protection for the data or any functionality defined in the NDEF standard, I only want to use the Mifare Desfire V1 as a storage of binary data. Therefore any possiblity to directly read and write on the card without any NDEF things is what I am looking for. Usecase 1: Connect to card, write 32000 bit of binary data Usecase 2: Connect to card, read 32000 bit of binary data. Can anyone tell me if this is possible and how to do it? If this is not possible, can anyone tell me which product/ NFC card I need to do so? Thank you very much. Best regards. Hans

[Jonathan_Iglesias]

 Hope you are doing great, 

I was able to use the TagWriter application for android and store a 4k NDEF in a DESFire with NDEF format, my recommendation would be that you confirm that you  created the NDEF file with enough space for the NDEF, check how are you formatting your NDEF that it is accordingly to the NDEF specification. as you may know the information regarding DESFire is secured under NDA so we cannot discuss much of the specific information about the card since this is a public forum. 

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