NRF52832 Comparator Module with NFC Front End Chip

[Ani]

I am Planning to Implement Card sniffing with NFC Front Chip !

Can I Utilize Comparator for card presence detection system senses the card by measuring the decay time of a transmitter signal after it has been turned off. When a card is in the field of the transmitter, power transfer occurs, and with more current the voltage on the transmitter output increases. The closer the card is to the reader the higher the voltage will be from the not present state. Measuring the decay of this signal by a comparator creates a simple A/D, since effectively the voltage is what is being measured

[ketiljo]

Do you plan to connect the NFC lines from the NFC front end chip to the nRF52832 comparator_ I guess it would work, but you need to protect the pin from over voltage.

[Ani]

 Actually there as shown in the above image the input is given to comparator analog pins and apart from that through NFC front end trf7970SPI interface to nrf 5232

Kindly suggest me is it fine to go and any modifications to be done 

[ketiljo]

I'd add zener diodes to ground and VDD to make sure the voltage on the pin doesn't go outside the max rated voltage range at VDD + 0.3 V or GND - 0.3 V. If you're close to the reader, the voltage induced in the antenna can be too high. 

[Ani]

Okay Sure I will do that

[ketiljo]

I've lost you here, sorry. I'm telling you that you have to make sure you don't violate the spec by exceeding the voltage range. How you do that is up to you.

Why do you think you need a 13.56 MHz oscillator? If it's part of the reader IC you are using, I can't help you with that.

The reference schematic for the nRF52323 is available here.