Passive RFID Item Searcher Particle Photon with RFM69(HCW)

Hello all. I am new to this forum and am seeking some guidance on how to get started with the RFM69(HCW) on the Particle Photon.

So I want to do a project with passive UHF RFID tags (either 433 MHz or 900 MHz) where the Particle Photon searches for a passive tag upon request using the RFM69(HCW). I looked into the RFM69 library on Github, and I couldn’t seem to make out what some of the headers and source code was outlining, but I assume it has to do with network packeting. I also looked through the device’s respective datasheet and found the mapping values but was unsure where the multiplexing process took place.

I plan to make an HTML page for basic command of the Photon. If a “Find device” button is pressed, then the Photon will guide the RFM69 to send a UHF signal in search for the device in question, by transmission and receiving, the tag in which may have its own UID, and this would mean that the RFM69(HCW)'s operation may both require the transmission and receive modes. I would also, because I want to power the Photon and RFM69 with a battery, want to know how to save power with the standby and sleep modes. The UHF tag will be placed on a physical item of choice away from the Photon, and read distance is preferred to be at least 20 feet (though it may be tricky to do with a passive tag despite using UHF signals).

My issue is trying to figure out how to get started with the RFM69 libraries and to see whether the RFM69 would even be compatible with the project vision I have. Any advice on how to get started or other suggestions is welcome.

Welcome to the Particle Community.

RFM69HCW can be used by installing the library RFM69-Particle.
The RFM69HCW communicates to the Photon using SPI bus, you need to set the pins for CS, IRQ and RST according to how you wire the RFM69HCW module to the Photon.

To read a UHF RFID tag you will need a UHF reader - the long range ones are expensive. You can’t use the RFM69HCW which is a packet radio link.

You could have 2 photons each with RFM69HCW modules to allow communication between them and one of the Photon’s connected to a 13.56MHz RFID (NFC) reader. Alternatively you could use WiFi from the Photon connected to the RFID reader.

Thanks for your reply and clarification, armor. I was hoping to be able to have the Photon interact with a passive tag meaning the tag wouldn’t require any additional power outside of the reader’s given power itself. So if I cannot use an RFM69 for this application and would require a reader to attach to it instead, what types of smaller readers would you suggest to reach a read range of about 20 feet or less?

Sorry I can’t recommend anything from experience. I am using a PN532 based module for Near Field Comms. The module supports I2C, SPI and UART - I always use I2C. Works very well and is much easier than building a circuit as the antenna capacitance is tricky to get right. For long range UHF - you need big antennas and power to energise the tag/card at long distance. I don’t know what your budget is but a google of UHF RFID readers will give you an idea - several hundred USD.

Okay, thanks a lot!