ST25DV, Energy Harvesting, EH, voltage pulse, voltage fluctuation, instable

[JDirk.1]

Hi all,

I put the EH_MODE to 0 to activate Energy Harvesting. The EEPROM is filled with zeros, so that the smartphone cant read a NDEF message but trying it for some time.

I am measuring the voltage on EH, in parallel i added a LED to visualize the EH function. The LED fluctuates, voltage is not stable. Its a fast blinking LED. Is it because the Phone tries to read the NDEF and therefore its going up and down? How do i active continues EH then? Is there a certain App needed? how can i force continued EH for some seconds? If i am reading a message from the tag, thats very fast (this is the reason i put zeros in the storage, to extend the time reading/trying and therefore seeing the LED blinking for longer).

Could someone give me some hints? I guess some basic understanding is missing ...

many thanks

I am using ST25DV ANT7 board (14x14mm Antenna)

17.01.2021:

I added a short video for explanation.

I guess what i see is the "Reader to tag" modulation, please see picture attached. How can i force the smartphone NFC to provide the 13.56 MHz without modulation? I could believe there is a certain EH function needed? Does the ST App has such Soltution?

[JL. Lebon]

Hello,

It would help to have a scope trace of the voltage output on VEH pin.

Can you put a scope on VEH an post it ?

Best regards.