EH with F746ZG+NFC08A1 as source and L476RG+NFC07A1 as load

[Kris-Kappa]

Hello!

I'm quite new to this, so I hope I'm providing enough information. I have successfully run a DS18B20 temperature sensor on a Nucleo L476RG and written the temperature to the tag of the NFC07A1. However, this only works while it's connected to a power source. Now, I have an NFC08A1 on a Nucleo F746ZG, and I want it to power the sensor (and on a next step read the temperature from the sensor).

When I run the Energy Harvesting (EH), I get approximately +/- 2.5 V on the tag part, which isn't even enough to light the green LED of the NFC07A1 fully.

On the reader/source side, I'm running the demo PollingTagDetect_NDEF.

Could anyone provide some advice on what I might be doing wrong, or let me know if you need any other information to assist me?

Thank you in advance,
Kris

 

[Rene Lenerve]

Hi Kris-kappa,

Following link is an Application note providing information about energy harvesting with ST25DV series (to help you a bit more):

https://www.st.com/content/ccc/resource/technical/document/application_note/group0/c2/1f/83/75/2c/f1/41/78/DM00329035/files/DM00329035.pdf/jcr:content/translations/en.DM00329035.pdf 

The tag will deliver on this Energy Harvesting pin the excess power received from the field and this depends on the intensity of the field (the parameters that can modify the energy received are the size of the antennas, the antenna tuning, the distance between antennas, ...). With the NFC7 and NFC8 boards you should be able to light on each led available on the NFC7. Take care to disconnect the Nucleo board before trying to light the led.

The voltage you measured seems to be a normal value and it could vary depending on the load connected to the EH pin.

I hope this can help you.

Kind Regards.