HLTA command issue

zanovilla · ‎2026-05-25

Hello, i need help for an issue with HLTA command.

I'm working with ST25R100 and I'm writing code direclty in uP without RFAL library.

I finished writing anticollision routine and it works fine, but when I try to put PICC in HALT mode it continues to respond to REQA command.

Because PICC comes from SELECT command, I think that registers settings are ok for HLTA command and I need to do no change about them. I take care not to turn off RF field so selected PICC does not return to IDLE state....

Also, if I send a READ command to PICC instead of HLTA I can read all data without any problem.

Any suggestion?

Thank you

Brian TIDAL · ‎2026-05-25

Hi,

could you connect a logic analyzer on SPI (CLK, MOSI, MISO, CS) and IRQ_ST25R100 and send us the raw log file?

It is recommended to use the RFAL. It is scalable and portable on different MCU. It has been tested against various NFC and ISO test suites. Just for my curiosity, what are the reasons for not using it?

Rgds

BT

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zanovilla · ‎2026-05-25

Only for optimized code reason.

Here are transactions with one PICC only in RF field until HLTA command. Do you note something wrong?

Thank you

Brian TIDAL · ‎2026-05-25

Hi,

could you send the raw log file (not CSV) i.e. .dvdat if digiview or .sal if salae etc. including the command sent after the SLP_REQ (50 00) i.e. when the tag replies to the second REQA?

Could you also confirm that this is a Type 2 tag from NxP? Could you provide information on the tag model (Mifare UL etc.)?

Rgds

BT

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