Does anyone has good experience with the low power card detect feature in the real world environment?

[Joseph Chan]

Posted on February 17, 2018 at 01:32

1. In addition to detecting the credit card size tag, can it detect smaller tag such as the one like the size of a quarter reliably?
2. Does it have false wake-up issue such as unexpected metal plate nearby or external radio source such as microwave oven, high power Access point, etc?

Thanks.

[Peter Boringer]

Posted on February 19, 2018 at 10:42

Hi Joseph,

I beleive that all the readers are ready to detect a tag with a quarter size of a credit card form factor with an antenna tuned  according to NFC/RFID standart/norma. Which type of pair Reader /Tag do you refer to?You second point is a bit generic can you please clarify your request and your setup?Thank

[Joseph Chan]

Posted on February 28, 2018 at 22:16

Hi Peter,

Thanks for the reply. I have the ST25R3911B-DISCO and X-NUCLEO-NFC05A1 boards. I will experiment with different setup. The GUI is also useful.

[Travis Palmer · Accepted solution]

Posted on March 06, 2018 at 13:14

Hi Joseph,

The ST25R3911B has some features build in to overcome environmental changes in wake-up mode. 

Automatic Averaging for example can be used to filter slow changing effects like temperature change or changing humidity. Only 'fast' changes like detuning by a tag or phone will be recognized.

The delta-window is another setting that changes the sensitivity of the wake-up feature. It allows to set a range around the reference value, where no interrupt is triggered. 

An interrupt can also be triggered by another device which operates at the same frequency range. A BLE or WIFI device is too different in terms of frequency to generate an amplitude change on the IC's input pins. A phone  which also sends out actively an HF field @ 13.56MHz will interfere with the inductive wake-up pulse and therefore also trigger an interrupt when being active in closer proximity. 

BR Travis