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marciokoko
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Rfid to control access

Sat Feb 18, 2017 4:38 am

Hi guys

I've worked with arduino and nfc to read tags on a card and on a key chain. But although they are related, I understand nfc is only good up to 20cm whereas Rfid can be good up to 100meters.

I want to give a user am Rfid tag and have the RPi read the tag as the user comes in the door in order to identify the user.

What Rfid reader could I use with the RPi2 or RPi3? Anyone know any projects like this one?

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topguy
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Re: Rfid to control access

Sat Feb 18, 2017 7:55 pm

Just to give a heads up, reading distance of passive RFID tags is very often directly connected to antenna size.
5cm antenna = 10cm reading, 20cm antenna = 1m reading distance.
And further distances needs more power so you'll probably need more than an USB-charger. Usually a 12V adapter.

Something like this probably:
https://www.aliexpress.com/item/1-meter ... .18.i9Eh5g

Heater
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Re: Rfid to control access

Sat Feb 18, 2017 8:05 pm

Depends what kind of RFID you want and how much you want to pay.

Cheap passive RFID tags will not get you 100m range.

For that you need active tags.

Looks like these guys have what you want: http://skyrfid.com/RFID_Active_Tag_24.php
Memory in C++ is a leaky abstraction .

Project XXX
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Re: Rfid to control access

Sat Feb 18, 2017 9:44 pm

You can use the rfid-rc522 reader for RPI 2/3...

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marciokoko
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Re: Rfid to control access

Mon Feb 20, 2017 12:25 am

Ok I just need to read tags about 1-2m. Sorry I mentioned 100m but I found an online table that classified RFID readers into 10cm, 20cm and 100m!

My idea is for people to identify a tag in a card as it comes into the store in the users wallet or purse.

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marciokoko
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Re: Rfid to control access

Tue Feb 21, 2017 3:27 pm

topguy wrote:Just to give a heads up, reading distance of passive RFID tags is very often directly connected to antenna size.
5cm antenna = 10cm reading, 20cm antenna = 1m reading distance.
And further distances needs more power so you'll probably need more than an USB-charger. Usually a 12V adapter.

Something like this probably:
https://www.aliexpress.com/item/1-meter ... .18.i9Eh5g
Ok so this reader will read mifare cards of 125kHz only. I have cards and tags for 13.56MHz so I would need to get new cards. Because I dont see any UHF 13.56Mhz readers, im guessing because UHF starts higher. So I really need a UHF reader and a set of UHF tags/cards as well, right?

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topguy
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Re: Rfid to control access

Tue Feb 21, 2017 6:42 pm

RFID at 125Khz and Mifare (NFC) tags at 13MHz are two different technologies. You will never get 1m reading distance with NFC cards/tags for example.
NFC is used in wireless payment and you don't want people to read your bank/credit-card at 1m distance.

mfa298
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Re: Rfid to control access

Tue Feb 21, 2017 6:50 pm

marciokoko wrote: Ok so this reader will read mifare cards of 125kHz only. I have cards and tags for 13.56MHz so I would need to get new cards. Because I dont see any UHF 13.56Mhz readers, im guessing because UHF starts higher. So I really need a UHF reader and a set of UHF tags/cards as well, right?
I have seen 13MHz USB readers before (although I can't remember if I tried it on a pi), and I don't know where it came from (I didn't get it).

Normally UHF refers to much higher frequencies (300MHz - 3000MHz), if rfid/nfc stuff refers to 13MHz as UHF then they're doing something different to the rest of things using rf systems,

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topguy
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Location: Trondheim, Norway

Re: Rfid to control access

Tue Feb 21, 2017 6:59 pm

There are 2.4GHz tags also, those need power but have much higher ranges ( and prices ). I guess those are in the UHF range a you call it.

There are plenty of USB readers for NFC that would work with the Pi. But those probably have a reading range of around of 5cm

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