I bought an Eval kit for an RFID module. The reader detects the card included in the kit just fine, but it can't find a separately bought, completely blank RFID tag. The reader is 13.56MHz and supports ISO 14443B. The Tag is 13.56MHz and ISO 14443B.

The RFID reader is the DLP-RFID2-EDK https://www.dlpdesign.com/rf/dlp-rfid2-ds-v114.pdf

The Tag in question is https://www.digikey.com/product-detail/en/microchip-technology/AT88RF04C-MVA1/1611-AT88RF04C-MVA1CT-ND/6831584



The software is a TI demo GUI called TRF7970A_GUI_WIN7_11_2013

Is there a special initiation process for new tags? or does it have anything to do with the security features of that specific tag?

Software Screen shot

Hardware Setup

EDIT: from http://ww1.microchip.com/downloads/en/DeviceDoc/Atmel-8672S-CryptoRF-AT88RF04C-Datasheet-Summary.pdf Section 2 Communications "The IC includes an integrated tuning capacitor, enabling it to operate with only the addition of a single external coil antenna."

Does that mean these tags need you to solder on an antenna?


2 Answers 2


You have the ground plane side of the RFID with the metal shielded enclosure facing the tag., which is not how to couple antennae.

Then you must read the RFID manual and use it with certain modes, codes and optional encryption.

Specs: While the DLP-RFID2 is designed to be surface mountable to the host PCB, it is not recommended that the user surface mount it to the DLP-RFID2U unless he or she intends to use only the external antennas. The ground plane on the bottom layer of the DLP-RFID2U PCB has an adverse effect on the read range of the internal antenna in the DLP-RFID2 module. If a developer wants to use the DLP-RFID2’s internal antenna while mounted to the DLP-RFID2U, then the module should be mounted using through-hole headers to raise the module up off the RFID2U PCB. The performance of the DLP-RFID2’s internal antenna will decrease as the distance between the two PCB’s decreases due to the proximity of the ground plane in the DLP-RFID2U.

  • \$\begingroup\$ thanks for looking into it. I've since tried moving things around quite a bit, but ultimately the module is already wired separately so the signal can get out. \$\endgroup\$ Jul 16, 2019 at 0:51
  • \$\begingroup\$ Where is host? antenna \$\endgroup\$ Jul 16, 2019 at 5:20
  • \$\begingroup\$ If you are asking where the antenna is, it is in the smaller module. It picks up the included card just fine. The thing is, I've already tried NFC with my phone on the tag, I'm pretty sure it has something to do with the tag, but I think I don't understand enough about RFID to pick it out of the user guide. \$\endgroup\$ Jul 16, 2019 at 5:24
  • \$\begingroup\$ 9600 Bd ping? Then sect 5.1 \$\endgroup\$ Jul 16, 2019 at 5:31

Is there a special initiation process for new tags? or does it have anything to do with the security features of that specific tag?

From my experience, "blank" tags have a sector hardcoded with manufactor specified information, you can always read this.

Occam's razor?

Is the tag broken? :) Check it with your phone.

  • \$\begingroup\$ hmmm... I think you're on to something, my phone couldn't find the tag either. But the thing is, I have tested like 6 of these tags. If you have time, could you look at my edit? \$\endgroup\$ Jul 16, 2019 at 0:54
  • \$\begingroup\$ The antenna is on the RFID it self. A magnetic field is used to induce a voltage in the RFID chip which in response sends its own magnetic field back, read up on NFC :), sadly I can't help you without having the device my self. My best advice would be to hardware debug and look if anything at all is being transmitted/transfered. \$\endgroup\$
    – Sorenp
    Jul 16, 2019 at 5:02

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