HITAG2 tag with HTRC110

[alasa995]

Hello everyone,

I am new to HITAG token types, and I am learning how to read them using the HTRC110 ABIC, I have a PCF7936 transponder token, from what I know, The HITAG protocol is reader speak first, so to be able to get the UID, one should send the WRITE_TAG command to the HTRC110, but checking the DOUT pin of the HTRC when presenting this specific token yielded a waveform similar to a Manchester encoded waveform, any explanation why?, if this is normal, then what type of modulation I should expect (waveform) when sending the WRITE_TAG command? One more thing, I assumed that there is a sort of authentication phase between the token (PCF7936) and the HTRC110, but If after sending the WRITE_TAG command I receive the UID directly, where's the authentication phase?

[alasa995]

Update: going through the PCF7936 datasheet, I found out that the IC has 3 modes in general, read-only, password, and cipher. The read-only mode will send the data in certain pages after a timeout, and password and cipher mode have to somehow compare the reader-stored password with the one on the transponder (programmed at manufacturing) to access certain pages on the EEPROM, but still, it will send the UID in both modes. What I am facing is that whenever I put the tag in the field it generates a waveform, although it is in password mode, I don't know why. also, sending the write tag command doesn't change anything, I still see that Manchester-like encoded waveform, has anyone faced this issue before?

[Fabian_R]

Hello sir,

Thank you very much for your interest in our products.

Yes, a Manchester-like waveform is normal. This is linked to the cutoff frequency. Please take a look at Section 9.6.1 of AN98080 where is mentioned.

Please take a look at the HTRC110 library HT2 example (RC110LB6) which is configured on the HTRC110 side: rc110lb6\HT2_A.A51 at the register level of the decoder state.