I started working with the NXP NTA 424 chips, however I haven't worked with any other nfc chips on a low-level basis (which is why I ask the following, probably simple, question).
My question is this: In the application note, it is specified, that one needs to "Select ISO DF (Dedicated File) Application" before writing to it. They further specify that this is the NDEF application. So my question is why? Why does the ISO specify that you need to select a file? Is this relevant for writing to this file (but could't you just specify where to write with the write command?)
If someone could explain to me the background to this, I would be very thankful,
Best regards, U_flow
To answer your question in a simple way, think of DF as a folder and NDEF file etc. as files inside the folder. The ISO select command specifies that you are selecting the folder level/DF. Now that your folder/DF is selected, by using WRITE command you'll specify that to which file you wanna write to(eg. NDEF File) along with the data to write. It works in hierarchy fashion same way as that of file system of Windows or MAC.
Hope it answers your questions and Happy Learning.