AnsweredAssumed Answered

The problem of PN548

Question asked by Zhibo Li on Aug 7, 2017
Latest reply on Aug 8, 2017 by Wigros Sun

The application of PN548 scanning ID card has the following problems:
1. Normal boot device After opening NFC, scan the ID card, it can successfully scan, the protocol information is: ISO 14443-3B. And my APP can also scan success.
2. Use the PN548NFC to scan the high frequency cards(repeat using the bus card or bank card), the scan is successful, the agreement information is: ISO 14443-4 and ISO 14443-3A.
3. Scan the ID card again, find that the scan ID failed, and the NFC chip has been trying to re-scan, and it is difficult to scan successfully.

Problem requirements:
First of all, is this a bug of PN548?
Second, the comparison log found that due to scanning high-frequency cards, scanning ID cards, log will appear non-stop:
         RW T4T state changed: <UNKNOWN STATE> -> <IDLE>

On the issue of high frequency cards affecting ID scanning, I tried to modify the following code:
The basic understanding is that the variable sCurrentConnectedHandle is reset to 0 each time when the card is moved out of the scan area.

 

Phenomenon vs. log:
The problem is compared with the log found that after scanning the high frequency card, sCurrentConnectedHandle will be assigned a value of 3, thus the ID card can't be read, but the high frequency card can be read normally.
The above changes after each scan card is completed, the sCurrentConnectedHandle is reset to 0, then ID card can be read and the high-frequency card can also be.

Will this: 1. Does this change affect other functions and have a greater impact on scan efficiency?
          2. If the changes affect other features, please provide the appropriate solution.

Outcomes