req RFID part info - Page 1
Forum section: electronics / projects

author: Jonathon_Doran
author_rank: Regular Contributor
timestamp: January 28, 2023, 12:27:13 am
content: I am investigating the use of RFID to help visually impaired people navigate large spaces. The idea is to place passive RFID tags at strategic locations, have a portable reader module connected to a mobile computer of some sort which could announce when one is near a particular door/hallway. Pathfinding through a nav-mesh is a possible extension. But to start, just letting someone know when they are a few meters away from a particular door would be useful.I've done a bit of thinking, but have not selected any parts.I am thinking of a ~900MHz reader module with a desired reading range of 2-3 meters. Passive tags we could discretely place.It would be nice if the module could generate an interrupt when we get close to a tag, but polling every 2-5 s would probably work too.I see a number of promising modules on Alibaba et.al. but am not sure if I could get a data sheet for one. I do not know the interface for any particular module, nor what type of antenna to use.If anyone has experience in this area, I would very much like some advice.Thanks,Jonathon Doran

author: bidrohini
author_rank: Regular Contributor
timestamp: January 28, 2023, 10:49:33 am
content: I don't think you'll get an RFID tag with this long range. However, here are some alternative suggestions:https://forum.arduino.cc/t/rfid-type-sensor-with-2-to-3-meter-range/114135/10However, if you ever consider using RFID tags and readers for any other project, you can considerRC522:https://www.theengineeringprojects.com/2023/01/interface-rfid-module-rc522-with-raspberry-pi-4.html

author: Jonathon_Doran
author_rank: Regular Contributor
timestamp: January 30, 2023, 09:48:21 pm
content: Thanks for the link. I'll look it over a bit. The module that was mentioned (NRF21L01) looks like it would work with active tags, which I want to avoid.There seem to be quite a lot of passive 900MHz tags with that range. I believe tollbooths use them (I also believe that is what I have on my car).My problem is that while the readers are available (and reasonably priced) there doesn't seem to be any documentation/data sheets for those modules.Another issue is that my degrees are in CS. Electronics is a hobby, but I have a very narrow area of experience. I am afraid that I'm overlooking stuff, and that I'm in over my head. This is why I was reaching out to the community. I figure someone may have solved this.I'll share some of my thoughts, and folks can pick 'em apart if they are crazy.900MHz UHF RFID can go up to 12m with passive tags. I don't need to push it that far.Here is an example of a passive tag I found:https://www.digikey.com/en/products/detail/avery-dennison-rfid/RF600526/5011648Here is a reader module that I came across. It has a reference circuit, but I'm still nervous about messing with this. Too many questions for someone without experience in this area. For example, why does UI have data in/out, but there is also a Wiegand interface? Why are there two baud rates, but no apparent way of changing them?https://www.aliexpress.us/item/2255800671559277.htmlIt is a dev board, but looks to be a reasonable size. It might be possible to connect to an Arduino and then a cell phone via Bluetooth.Power is a bit of an issue. I know one person who carries around a power brick in their backpack, but a more practical version might be a LiPo battery:https://www.amazon.com/EEMB-2000mAh-Battery-Rechargeable-Connector/dp/B08214DJLJThat is 3.7V, 2000mAh. The RFID takes 180mA. An Arduino Nano IOT takes 7mA. Together this is well under the battery's standard discharge (0.2C or 400mA). The max discharge is 2C (4000mA). A rechargeable with 10 hours with a minimum 1hr recharge time.