Some questions about ST25RU3993

[MYoun.4]

Hi.

I'm graduate student, researching UHF passive RFID tag, in Dongguk university, Seoul, Korea.

Thanks to offer materials like documentations, video. It was really helpful for my study. 

Before purchase the ST25RU3993-HPEV to measure research results, I want to check some questions. 

At page 39 and 49 of ST25RU3993 datadheet, document says "In EPC Class 1 Gen2 protocol, the decoder supports long Rx preamble (TRext=1) for FM0" and "Short preamble is supproted for Miller 4 and Miller 8 coding". I wondering it means "FM0 coding can't use short Rx preamble (TRext=0) to communicate with ST25RU3993".

At page 48 of same document, if I set Rx_crc_n=1 (Rx without CRC), does it mean ST25RU3993 never check CRC for all received data from a tag?

Finally, at UM2268 User manual (about ST25RU3993 GUI software), I want to know can I custom commands like Read/Write.

Thanks for your help.

[Bart Herse]

Hello MYoun.4

• for FM0 it is required to set TRext = 1

• in case Rx_crc_n=1 (Rx without CRC) the CRC-16 can be fetched form the FIFO so that the MCU can check the CRC. The reader IC will not check the CRC with this configuration.

• Read and Write commands are already implemented to perform read and write on the memory banks. If special commands are needed It is possible to entirely customize reader commands. So it also possible to manually replicate Read and Write commands.

Cheers,

B

[MYoun.4]

Hi Bart Herse.

I really appreciate your answer.

I want to know three more things about ST25RU3993-HPEV.

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1. In case of Rx_crc_n=1(Rx without CRC), which does it mean "tag shall not append CRC data in its reply" or "tag shall append CRC, but RFID reader does not check it"?
2. According to EPC Gen-2 protocol, FM0 coding (tag to reply communication) shall ends with "dummy-1", is it valid with ST25RU3993-HPEV?
3. At page 37 of UM2268 User manual ST25RU3993 evaluation board software, Figure 34 shows four scanned tags with 1word(2bytes) or 6words (12bytes) or more words EPC length. Dose ST25RU3993 get these EPC data through tag reply to ACK command? Also, I'm wondering there is a minimum length of EPC data that shall be appended to communicate with ST25RU3993-HPEV, i.e., is it possible to append just 1bit EPC data in tag reply to ACK command?

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I'm really thanks for your help.

[Bart Herse]

Dear MYoun.4,

1.: CRC-16 will not be checked by the reader IC. The CRC-16 will be put into the FIFO so that the MCU can fetch it and process it.

2.: How the tag ends its frame cannot be altered by the reader. If the question is , if ST25RU3993 can decode FM0, then the answer is yes.

3.: The EPC data is received upon the ACK command. As the length field in the PC defines the EPC ´length in number of WORDS (2 bytes), a 1-bit EPC data length is per my knowledge not possible.

Cheers,

B