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TRPGR30ATGC: Evaluation kit or turnkey solution

Kevin Xiao32
Prodigy 40 points
Part Number: TRPGR30ATGC
Other Parts Discussed in Thread: MRD2EVM, TMS3705

Hi TI,

I want to use a RFID chip to differentiate identical movers, so I want a transponder + reader system with low range (to avoid reading multiple movers at once), 10cm range is enough.

Are the 130khz RFID chips (specifically TRPGR30ATGC) best suited for this type of application? If it is, can you recommend an evaluation kit or turnkey reader system?

Thanks,

Kevin Xiao

  • 0
    TI__Guru*** 128125 points
    Hello Kevin,

    A few questions before I can say whether HF or LF RFID is best for your application.

    1) Is 10cm a minimum range, or can it be shorter for the 'max read distance'?
    2) You mention movers, so it makes me think you want to read the tags while the reader and/or tag is in motion, is that the case? If so, how fast is the movement? Do you have an estimate on how much time the tag will be near the reader?
    3) What size and/or form factor are you looking for on the tags, and what size antenna are you expecting to have on the reader side?
    4) Will there be any presence of metal near the tag and/or reader antenna?
    5) What kind of cost per tag are you looking at for this application?
  • 0 in reply to Ralph Jacobi
    Prodigy 40 points
    Hi Ralph,
    Thank you very much for your reply.
    I've ordered the MRD2EVM kit and some TRPGR30ATGC samples, I guess I jumped the gun a bit. :)
    The reading distance can be as low as 2cm.
    If it is required, the movers can remain stationary near the reader. Otherwise, it will be moving at around 0.5 m/s.
    The tags should be <3mm in diameter, and <50mm in length.
    Up to $20 for cost / tag is ok.

    The presence of metal is a good question. We are considering 1 option with no metal at all between the reader and tag, and another option where the read and tag are separated by 10-15mm of PCB with heavy copper traces. Do you think it will be readable at all through this copper layer?

    As far as metal penetration goes, is there any difference between the tag frequency types?

    Thanks,
    Kevin
  • 0 in reply to Kevin Xiao32
    Prodigy 40 points

    Hi Ralph,

    I received the Eval kit already, amazing shipping, delivery on Saturday!

    I did some testing with the kit, it looks like reading through copper and even stainless steel layers is possible, provided there is a gap between the tag and the metal barrier.

    This may be the wrong thread to ask the next question, but I will try anyways. Can you recommend me a LF RFID reader IC, with package thickness of <1.05mm?

    I noticed your 13MHz reader ICs have this package size, do 13MHz tags come in the glass capsules at all?

    Thanks,

    Kevin

  • 0 in reply to Kevin Xiao32
    TI__Guru*** 128125 points

    Hello Kevin,

    A lot of address now, so I will try and keep this as organized as I can.

    Kevin Xiao32 said:

    I did some testing with the kit, it looks like reading through copper and even stainless steel layers is possible, provided there is a gap between the tag and the metal barrier.

    Stainless steel is actually easier to read through than cooper as it affects the magnetic fields even less than cooper. Though you mention cooper traces, so if it's not a sheet I could see that being better, though I'd expect the PCB has a metal ground plane between layers? All that said, it's non-trivial to read tags through metal in general and performance definitely drops while doing so. LF RFID is the only way to really do that with TI products by the way, our HF tags/readers don't work well with metal between them.

    The gap is definitely crucial as being right against metal de-tunes the tag antenna making communication impossible.

    Kevin Xiao32 said:

    This may be the wrong thread to ask the next question, but I will try anyways. Can you recommend me a LF RFID reader IC, with package thickness of <1.05mm?

    The TMS3705 is the only catalog non-automotive reader from TI that I am really familiar with, not sure about it's package thickness though.

    Kevin Xiao32 said:

    I noticed your 13MHz reader ICs have this package size, do 13MHz tags come in the glass capsules at all?

    Nope, they are usually in thin inlays or stickers. Also there are some molded tags which are used in applications that need more durability.

    Regarding prior comments...

    Given the range and speed (if moving), HF RFID would be a good fit if there is no metal between the tag and reader.

    You can feasibly do an inventory command in 10ms, though 15ms would be safer in terms of giving the tag more time to receive RF power. The trick would be determining when to send the command, or if there isn't a way to know beforehand, deciding on a reasonable interval to send out commands.

    At a 15ms time, you are looking at about 0.75 cm of distance traveled by the tag when moving at 0.5sec (unless I messed up something math wise?)

    For reference... we read a single block of data from a moving RC car which was going about 15-20MPH with ISO15693. So the speed is very doable haha.

    The tag dimensions are a little interesting to me... I presume diameter is in context of a glass transponder? Would thinner thickness be better? Length of 50mm is okay, there will be some height to it as well though. Would 25-30mm of height be okay?

    And yes as mentioned above, LF RFID does better with metal.

    I personally would see if I could avoid the metal in front of the tag and then use HF as this really is an application that screams HF RFID, but if the metal turns into a requirement and the LF RFID setup handles reading through it with reliability you are comfortable with, then you could go that route as well.

  • 0 in reply to Ralph Jacobi
    Prodigy 40 points
    Thanks Ralph, this was very helpful, and you are totally right about the assessments. Reading through metal has become a constraint, so we'll likely do a slow read using LF, and hopefully tune the antenna properly.
    I'd also like to share some info on the forum here for others who may be using the Eval kit. The most important step of testing commands is to be able to send proper characters through terminal. For this, I strongly recommend RealTerm due to it's ability to send pure hex data. Putty is not sufficient.
    To use RealTerm, set display settings to Hex[space], half duplex, port baud to 9600, no parity, 8 data bits, 1 stop bit, no flow control (unnecessary at this baud rate). when sending, use this format "0x01 0x03 0x80 0x 80 0x80 0x83".
    I found the response from tags is usually good for the first few characters, then errors start to increase at the end when the signal is weak, due to the tag running out of charge. For the future, I recommend TI create a multi-charge-burst read function, or allow the user to read 1 specific byte at a time from the tag, i think it will improve the reading range quite a lot (though it will be relatively slow).