Grove NFC low power mode

I have a low power application where I need to read RFID tags. I purchased the Adafruit PN532 breakout board to develop the code and it works fine, but the board is physically too big to use in my prototype. I purchased the Grove NFC and the code I wrote works fine with it, but there doesn’t seem to be any way to put it into a low power mode between tag readings.

I actually had written code to control the reset pin to put it into Hard-Power-Down mode, which is 2 uA. Unfortunately, the Grove board ties this pin high and there’s no pin realistic way to access the pin. The Soft-Power-Down mode is 45uA, which is OK, but I can’t figure out how to assert that mode. I can do it with the Adafruit board, but it doesn’t work with this board.

Anyone know what the magic command is or where I could find additional documentation?

Forgot to mention I’m using I2C.

I’m starting to think this isn’t necessarily a software problem. I removed all connections to my host board and simply connected power to the NFC board. It defaults to 36 mA. Then I shorted the pin side of the pullup resister connected to the reset pin. That should do a hard power down to 2 uA plus the current through the pullup, which is 10K Ohms, so another 100 uA. Instead, it goes up to 60 mA.

I’m definitely missing something.

@jsheaney Are you using the software from GitHub at Seeed?

No. I wrote my own code, which works fine on the Adafruit breakout board and actually works fine on the Grove board. My only problem is getting into low power mode. The GitHub code doesn’t look like it addresses power modes at all. It looks like very basic read/write examples.

That was not worded well. My code doesn’t run on these boards; it runs on a Nordic PCA 100040 dev board for nRF52 development. I’m not using an Arduino and my code is written in C, not C++.

From this specification, low power is only about software.If you want to know whether there is a relationship with peripheral hardware, you may need to consult the original FAE.Grove NFC did not consider low power when it was designed, and we did not test i