Simultaneous UHF RFID Reader not reading my tags

Hello.

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I have one UHF-RFID modules from M5 which i use for near tag reading and writing.
Now i have purchased the Sparkfun Simultaneous UHF RFID Reader but the reader is not reading the IDs I have written to my tags. They got read but i can’t see the ID I have written to them.

What could be the problem and how can i use both readers in the same project?

Thanks for any help and/or suggestions.

Your problem description is ‘a bit’ cryptic and hard to understand and thus help. If you use EPCglobal UHF Class 1 Gen 2 / ISO -6C it should work, a couple clarifying questions:

What kind of UHF-RIFD modules you have ?
What device do you use to write them ?
What did you write ( EPC, USER memory etc )
Can you read the expected result on the device you wrote them ?
What does the UHF-RFID read from the modules (ESP or user memory)?
What output do you get and what would you expect ?
What sketch/software did you use ?
have your tried the URA (universal Reader Assistant) from Jadak (former ThingMagic) to read ?
Any other info ?

Hi and thank you for your reply.

Right now i use the UHF-RFID module from M5 stack.
I use it for writing and reading using the library that comes with it.
Using the write and read sketch of that device i can write the tags and read exactly what i wrote to them.

The tags i bought are EPCglobal UHF Class 1 Gen 2 / ISO -6C and work fine.
If i present that tags to the Sparkfun Reader they got read but i can’t see the ID i wrote to them.

the m5 reader/writer uses a 4 bit ID. But its not visible in the EPC i get from the Sparkfun reader.

Never heard of that tool:
URA (universal Reader Assistant) from Jadak (former ThingMagic)
I’ll give it a look.

Thank you!

Jeevan -

you are looking for something that in the near field HF world, would be possible with passive LF and HF RFID tags and higher power readers and larger antennas.

Passive UHF utilizing the near field has very short range (almost touch - and is not widely available in the market) we experiemented with these several years ago - the frequency band really prohibits flexibility for using the near field.

anyway - if you want this range, you have three choices.using passive LF or HF (in the near field) or using passive UHF in the far field.

the questions you need to ask of your proposed application to decide which technology to use are: how big can reader antenna be? how much current will your power source be able to have for the reader? how big can your tags be? what are the costs you are thinking about for tags, reader, reader antenna? what is the environment (outside, inside, metal in the field, unknown materials in the field, people in the field, etc.)?

just to get started.

If you want to learn more, please visit our website UHF Rfid Reader Modules.

Good day, 

Thank you for the quick response. I am also a part of the team working on this project with Jeevan.

The reason we decided to go with UHF rather than HF is because of the size constraints. The reader cannot be larger than 3.08cm x 2.06cm x 0.5cm, while the tags must not be larger than 2cm x 2cm x 0.5cm. Using UHF in the near field region is not feasible, as you stated, so we are considering far field communication.

To answer the other questions posed, the system also needs to operate both indoors and outdoor around metal surfaces. While we aware that metal surfaces affect the quality of UHF signals to a greater degree than HF, we have seen solutions where people are able to deal with this problem. For one of the batteries being considered, the current supply would be 15mA pulsed or 0.2mA continuous (as specified in the datasheet). 

As for price, Jeevan would have to get back to you on that. 

-Sarika

ok - i think you most likely have described a system which includes a module for the reader - if you want to use TI based solution for that - please see: https://tsscompany.eu/murm-evaluation-board/

is this battery powered UHF reader? Did i understand that correctly? (You many want to rethink your frequency band choice then and have another look at HF, using the TRF79xxA reader + MSP430...we have app note for ULP operations, but seems as though you have made up your mind, and maybe you need more range, but maybe you don't get much more with a UHF reader and tag that small anyway)

for the tag, you will have to get those from any of the multitude of vendors found via search engine

The reader we are required to developed needs to be battery powered as it is to be carried by a user. I will check out the link that you have recommended. Thank you for your suggestion. 

The reason that we eliminated HF as an option was due to the size of the tags required to obtain the necessary 1.5m to 2m range. Was that a misunderstanding on our part? Can the tag antenna size meet the size specified in my previous post for this range?

you will have trouble meeting the distance requirement because of the dimension constraints you have placed on both sides (reader and tag), no matter the RFID frequency, plus UHF reader board that small will still need antenna...remember that in 900MHz band, one wavelength is about 1 foot.. this means a 1/4 dipole antenna would be about 3 inches...here is a chip antenna though,

http://www.pulseelectronics.com/download//wpdf/pdf

but it is still 10mm long...and you still need clearance under it + your reader IC + MCU (could be CC430 or CC11xx or CC12xx + MSP430)

for the tag - you will have a challenge there...take a look at ALN-...or get some and test them out - these are about the size you want to use. 

http://www.alientechnology.com/wp-content/uploads/Tag%20Family%20Overview%20(-11-06).pdf

you could also look at BLE...it will require a battery on the tag side, but you may be able to get the reader size down to what you are proposing and the distance you are looking for...not exactly RFID, but you could get about the same user experience and the battery on the reader side will last longer.

maybe this is just another option for you.  

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