RFID Toys

HOW-TOs and other projects : Active RFID tag collision for NRF24L01 system

Mon, 20 May 2013 23:37:32 +0000

Author: Nik
Subject: Active RFID tag collision for NRF24L01 system
Posted: 20 May 2013 at 11:37pm

Hi Amal,

Thanks for your quick reply. I agree with the randomized method. However I am looking for help where Tag in a zone is about 2000. I have thought in mind to use RPD register feature of NRF along with random sleep time. However right now I am trying to get hands on with interfacing of AVR and NRF24L01P and not sure how much RPD register method would be successful. Also I am afraid of increase in current consuption of tag as it need to use in RX mode for RPD. So worried about battery life of CR2032.

Edited by Nik - 10 hours 22 minutes ago at 11:38pm

HOW-TOs and other projects : Active RFID tag collision for NRF24L01 system

Mon, 20 May 2013 09:39:08 +0000

Author: amal
Subject: Active RFID tag collision for NRF24L01 system
Posted: 20 May 2013 at 9:39am

Hi Nik,

Active systems typically introduce a randomized timer skew value so that you have your primary delay of X and apply a randomized skew of +/- Y to ensure that if collisions occur, they will not occur the next transmission cycle. This approach is very effective, and collisions can be kept to a minimum until you have a very large number of tags in the same coverage zone. Some systems can handle up to 1000s of tags before collisions become a serious problem. I believe OpenBeacon could probably handle somewhere in the range of 250 or so tags before you'd have problems... but of course you could always adjust the collision system used in firmware and upload new firmware yourself :)

HOW-TOs and other projects : Active RFID tag collision for NRF24L01 system

Mon, 20 May 2013 03:17:29 +0000

Author: Nik
Subject: Active RFID tag collision for NRF24L01 system
Posted: 20 May 2013 at 3:17am

Hi All,

I am newbie to RFID. I am very much impressed with the technology and OpenBeacon project of Active 2.45Ghz Proximity Tracking RFID Tag. I have gone through the documentation and looking forward to build the project from scratch. While going through pages at http://www.openbeacon.org I have understood and got confidence level to build the system. However one question in mind pulling me back in this project. And I need your valuable guidance on this. The question is that in openbeacon project all tag are actively advertising themself to the receiver/reader. And there is much possiblity that at a particular time of instance in a setup two or more tag can try to advertise themself which will lead to collision at receiver.

I am not able to collect solution on this collision problem. So would like to have your valuable guidance on this.

< id=dstb-id =>dstb() < id=dstimer => // < id=dstb-id =>dstb()< id=dstimer =>//

Edited by Nik - Yesterday at 3:23am

Reader Projects : Archives Clones - RFID tagging

Tue, 30 Apr 2013 04:57:51 +0000

Author: SmallGIS
Subject: Archives Clones - RFID tagging
Posted: 30 April 2013 at 4:57am

Hello,

project to find a solution which applies to the inventory of trees.
Looking for a device (as in the subject line), or a person who could do such a device that meets the following specifications:

Transfers reading through Bluetooth (in the role of just reading need not write)
He can read the TAGS (tags specification can be sent by email - frequency LF 125KHz ) buried underground at a depth of about 20cm
You can carry with you (do not have to be a hand-held device could be something like a sword, a metal detector)
The battery unit can withstand a minimum of 4 hours and weighs 5kg

Waiting for the proposed solution.

Reader Projects : RFID reader in stethoscope

Mon, 15 Apr 2013 16:53:01 +0000

Author: amal
Subject: RFID reader in stethoscope
Posted: 15 April 2013 at 4:53pm

Hi jopiek,

For antenna design notes, check posts in this section of the forum; http://rfidtoys.net/forum/forum_topics.asp?FID=21&title=howtos-and-other-projects

The book is now quite dated, and there are several Mifare RF readers available that you could attach your own antenna to. The trick will be to properly tune the capacitance of the antenna, but many of the OEM reader boards designed for use with an external antenna will already have these tuning capacitors on the board, and you'll just have to make sure you wind your antenna to the appropriate inductance.

I think the main issue with an RFID enhanced stethoscope is going to be the metal portion of the stem that the drums of the check piece and diaphragm attach to. If possible, you will want this to be made of plastic. If you can't find one with a plastic stem, you may try 3D printing one.

HOW-TOs and other projects : Free developer tools with SQL

Sun, 14 Apr 2013 02:36:29 +0000

Author: jopiek
Subject: Free developer tools with SQL
Posted: 14 April 2013 at 2:36am

maybe you should have a look at a solution like Xammp? It has MySQL and PHP in one package.

Reader Projects : RFID reader in stethoscope

Sun, 14 Apr 2013 02:33:54 +0000

Author: jopiek
Subject: RFID reader in stethoscope
Posted: 14 April 2013 at 2:33am

For a school project we want to 'enhance' a stethoscope with an RFID reader. Preferably a Mifare one because we have already created software for that since we had readers and tags of that type (mostly mifare classic) lying around.

We obtained the RFID Toys book and a number of other materials. Since I'm not very affluent at physics, creating our own antenna is quite a challenge (although a physics teacher colleague is looking along and he might figure things out).

I have seen the SkyeTek's SkyeRead M1-mini in the book of course but it is quite expensive, not very available (especially the TTL variety) etc. We already have a bunch of readers and want to connect it (initially to an arduino or other uC that we are familiar with).

The diameter of a typical stethoscope is about 4.3 mm (1.7 inch). We might be able to create out own prototype PCB antenna by etching it, but we still hope to find out what our best options are for now.

(so any help or suggestions very much appreciated), thanks!

Edited by jopiek - 14 April 2013 at 2:35am

HOW-TOs and other projects : Mifare Ultralight cloning

Mon, 08 Apr 2013 10:14:06 +0000

Author: TintesB
Subject: Mifare Ultralight cloning
Posted: 08 April 2013 at 10:14am

I've been searching online for UID changeable ultralight keys and come up short. Have you run into them somewhere?

HOW-TOs and other projects : Mifare Ultralight cloning

Sun, 07 Apr 2013 19:18:04 +0000

Author: amal
Subject: Mifare Ultralight cloning
Posted: 07 April 2013 at 7:18pm

PS, this is why it's a good reason to secure your RFID access control system in other ways, like using a random rotating key that is written to the "normal" writable blocks on an Ultralight tag and kept in sync with the central system, as well as other external security measures - e.g. a person can't enter a door on one side of the facility and another door on the other side 30 seconds later.

HOW-TOs and other projects : Mifare Ultralight cloning

Sun, 07 Apr 2013 19:16:21 +0000

Author: amal
Subject: Mifare Ultralight cloning
Posted: 07 April 2013 at 7:16pm

Hi there,

Most likely it works like this; where Mifare Ultralight cards have UID bits written and locked at the factory, they are likely selling special tags with OTP or one-time-programmable bits where the UID bits of a normal Ultralight tag are, and the programmer simply reads the UID bits from the source tag and writes them to the target tag. I'm pretty sure the magic all resides in the special blank cards they sell. You might even be able to program them with a normal RFID writer and just target those memory blocks, but that's just a guess.