Hi,
That's not so easy to answer. For more background information see the PDF docs/DataStorage.pdf inside the SDK.
Summarized: the total capacity is dependent on:
- Your firmware size: more Flash space occupied by your firmware == less space left for data storage.
- Your compression algorithm running in firmware:
the algorithm itself takes space, but delivers a certain compression ratio, tailored for your use case;
plus the compression will likely yield different results given different inputs. This may result in a slightly different storage capacity. - Your resolution: how many bits per sample do you need to store for your use case?
The data is not directly accessible from the NFC interface: you will need some logic running on the tag reader side to at minimum repeatedly read the memory of the NFC interface. Either you take the command- response approach - as is done in the Android APP; or you adapt the firmware to automatically update the memory of the NFC interface in firmware - an approach necessary for readout via iOS.
Apart from Android and iOS, you can also use an NFC USB dongle, and run a Python script or anything else on a PC (Windows, macOS, Linux).
Practically: changing the storage capacity using the demo firmware supplied in the SDK is very quickly done using the diversity settings in app_sel.h in the project app_demo_dp_tlogger: e.g. comment out the defines STORAGE_COMPRESS_CB and STORAGE_DECOMPRESS_CB to disable compression; that will most certainly have an effect.
Is there a specific feature or setup you had in mind?
Best,
Dries.
