RFID Multiple tag reading at medium distance

Hi all,

I’m a programmer but I have had very basic exposure to electrics and things like Arduino, so please bear with me.

I would like to make a playing-card reading system. The reason being we would like some interface/overlay to show which player has what cards, such as for poker. Ideally I would like to be able to read RFID tags attached to playing cards and have the arduinos communicate to a raspberry pi which will handle the updating on the overlay, this side I can manage with but I would like some guidance on the RFID side.

Currently I am using an MFRC522 reader attached to my Uno. I have been able to read the RFID tags one at a time with a range of <1 cm. This means that each player has to present the cards in order and also we would need to have the reader on the table which does not look pleasant.

A central database will handle mapping tag UID to what the card represents so all I need to read is the tag’s UID.

I have been looking at longer distance RFID readers and have found some. I also found another standard to ISO 14443, which is ISO 15693. This supports 13.56 MHz at around 1 metre distance (which I planned to decrease to ~ 15 cm via the antenna gain) and supports anti-collision which is ideal for scanning 2 cards at the same time. However I have not found any readers for this that are compatible for the Arduino. I’ve also briefly touched on UHF but it seems quite expensive but if it’s the correct way to approach this then I am willing to venture down the UHF route.

Potentially if we use a standard that supports anti-collision then it would be nice to be able to count each player’s chips automatically too.

So my question is: What can and can’t I do? Am I able to purchase a reader and tags that will allow me to read 2 cards and 40 (max) chips at a distance of 15cm? Or will I just have to stick to reading one card at a time?

Many thanks in advance.

I've also briefly touched on UHF but it seems quite expensive but if it's the correct way to approach this then I am willing to venture down the UHF route.

Yes it is the correct route for reading that many tags in the field.

The problem as I see it is in controlling the range so you do not read the whole stack. Also there is a problem with players potentially exposed to high levels of radiation. Spark Fun do a cheap reader although it is not in the dirt cheap bracket it is considerably cheaper than the others I have seen. There is a distance function on these readers so maybe there is scope for that to differentiate but I am not sure.

Anti collision systems at 13.5MHz only can cope with a limited number of tags in the field at the same time.

Also is this project basically a scam so you can cheat at poker without the other players noticing?

Hi Mike,

Sorry for the late reply.

I've taken a look at the sparkfun reader thanks. While I was looking I stumbled across a HF RFID specification. These still benefit from the longer range and anti-collision. ISO18000-3M3 even states it's designed for stacked inventory tracking and "poker chips". I believe the commercial name is NXP ICODE ILT, and even found a YouTube video of it reading 54 playing cards simultaneously in remarkably short time. Have not managed to find some readers/tags though.

Do you think this would be a better option? The HF instead of UHF will expose the players to a lower frequency than UHF I think. Or do you still think UHF is the best here?

Also is this project basically a scam so you can cheat at poker without the other players noticing?

Not at all, we're doing charity tabletop games that we plan to stream live to our audience on Twitch. We did a test run with hole cams but with only 2-3 people behind the cameras it was quite slow for the audience to be updated on the livestream overlay, and tracking chips was a nightmare. I'm trying to at least automate card reading without using obnoxious barcodes or OCR and figured RFID would be best.

Cheers.

Or do you still think UHF is the best here?

It is the only option that can read tags with that many different tags in the field, so I don't think you have a choice, unless you are content to pass a card over a reader or readers to "log" them into the game. You can use multiple readers like I did in this project:- Crazy People

The range of the UHF system can be controlled by controlling the transmitter's power or configuration of the antenna. However the latter is not a simple thing to do at these sorts of frequencies. If you want to delve into this then look at Ham radio sites for information on UHF antenna.

figured RFID would be best.

No offense but I think this project is one of many where people assume that RFID is the answer, only because they don't know much about how RFID works and what it's limitations are. Even if you had a UHF reader that would not guarantee you could get the project to work.

We've decided to stick with reading cards only and have the chips tracked by hand. Going to have 2 readers per player which they place their cards on and keep them there, and then 5 for the river.

If and when we have the budget to go down the (U)HF route I'll have another look at the stuff you mentioned and see if it is viable.

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You are correct by saying even if we get a UHF reader there's no guarantee it would work. I would say I have some basic idea of how RFID works and its limitations. We have tried using OCR and it didn't work properly. QR codes seemed to be the most reliable but we did not want to deface the cards, and the code will be viewable on the river. RFID seems to be good way to read the cards, albeit not perfect either, but unless there is a better solution I believe RFID would be the best here.

Thanks for your time Mike.

Cheers.