nt3h2111 cannot activate pass-through

[m_wagrodzki]

Hello.

I'm developing a board with NT3H2111 NTAG I2C Plus IC. I want to use pass-through mode, but I'm having trouble activating it. I cannot write PTHRU_ON_OFF bit in NC_REG session register. I have no trouble with setting any other bit and reading it back via NFC, but when I set this specific one bit, it doesn't change. I know there need to be both interfaces reachable to activate pass-through, but there are. The alorithm is following:
-NTAG is powered down, MCU waits for the interrupt from GPIO connected to field detect pin

-when FD goes down (when I stick the phone to the atenna), the interrupt is being asserted

-during an interrupt, I power up the chip (tried powering it non-stop - didn't help) and write the session register NC_REG - I'm setting PTHROUGH_ON_OFF and TRANSFER_DIR bits to 1

-in the meantime I'm polling the PTHROUGH_ON_OFF bit on my phone, but it can never detect it

I tried reading the NC_REG from i2c right after writing it - it stays 0b all the time. What am I missing out?

[emnipetro]

hp customer support Number provide the support to their user anyone is having some problem then he or she can share your problems here.

[m_wagrodzki]

I managed to cope with the problem myself. You have to write a few times to NC_REG, it will finally hatch. The pseudocode of algorithm I used:
while(1){

set_NC_REG(0x7D)

wait(4ms)

NS_REG=read_NS_REG

if((NS_REG & 0x10)!=0) break;

}

All of this while polling NC_REG for PTHROUGH_ON_OFF on the phone.

[Kan_Li]

Hi Marek,

Great to know it has been solved on your side, we have docs on that topic, and you may refer to https://www.nxp.com/docs/en/application-note/AN11579.pdf  and https://www.nxp.com/docs/en/engineering-bulletin/TN00042.pdf  for more details.

Have a great day,
Kan

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