[SOLVED] Making 2 RFID reader/writer modules talk to each other

[deepak4you]

Hello everyone,


I'm working on a project to communicate between two boards OTA (over-the-air) but within close proximity. I could consider LED/laser based communication, but that is too directional. WiFi or BT are wireless, but using them increases the BoM cost. I considered NFC/RFID, but all my research and understanding indicates (please do correct me if I'm wrong here) that I can't do much with RFID tag because the tag itself is hardly capable of processing other than fetching and storing data.


I then thought if it would be possible to make two MFRC522 reader/writers talk to each other, similar to serial comms where Rx of one side goes to Tx of other side and vice versa, but my search did not get me anything worthwhile. I do know that NFC is used to share data between two NFC enabled phones (like contact cards and other small data), so I'd assume it should be doable, but I don't have any pointers to start working.


Any kind soul out there might have any info that could be useful for me with my project?

Regards,
Deepak

 

[betwixt]

I wouldn't say impossible but I would say impractical. The first problem is both units send bursts of transmitted power to enable any tags in the vicinity so you would have to synchronize them so they alternated burst timing. Secondly, they expect data to address memory in the tag so you would have protocol difficulties and finally, RFID modulates by loading the RF field and recording the effective drop in 'Q' at the transmission antenna, I don't think those devices have capability to do that.

You can get ESP8266 or ESP8285 modules for about the same cost as an RFID system and set them up as peer-to-peer WiFi links. It not only overcomes your communication problem, it gives you a high speed processor and memory to run any additional software in. You can even update their firmware or configure them OTA.

Brian.

 

[deepak4you]

That was a lot of helpful information Brian, especially not knowing the detailed specs of how RFID works at electronics level. Indeed feels like this won't fly off with RFID. The WiFi link was an option I had considered, but wasn't sure of the price. I'll look into it further and see if cost-benefit works in its favour. Thankyou so much for your inputs Brian, truly appreciated.

Regards,
Deepak

 

[BradtheRad]

Possibilities:

* Ultrasonic transducers communicating via audio link? Suited to slow or occasional communication. Directional to a lesser extent than optical.

* Inductive/wireless charging is becoming more frequent as a project for experimenters. Of course it's important to make the receiving sensor resonate to the sending unit frequency.

 

[deepak4you]

Audio link sounds interesting. First thoughts are that we'd need ADC and DAC both (for two way comms), and transducers themselves only generate a single tone, no? The one of their resonating frequency?

 

[FvM]

NFC has a peer-to-peer communication mode that's supported by many NFC reader IC. But MFRC522 is no NFC reader.

 

[betwixt]

ESP8266 will give you a 160MHz processor, several IO pins, Wifi capability and enough memory to hold quite big programs. Cost can be below $1.00 if you buy from China. There are lots of development tools and development boards too.

I have one here in a product under development that is driving an LCD and bank of indicator LEDs, reading a 16-key keypad, interfacing to a 1Mb external I2C memory and WiFi linking via MQTT to a PC and several other modules. Only 13% of its internal memory is in use and all the firmware can be updated over WiFi from the development PC using a standard HTTP (web page) interface.

You can adjust the transmitter power to limit the range if necessary, at full power they cover around 100m using their internal antennas.

Brian.

 

[deepak4you]

After reading all the inputs, i guess i'll consider the ESP alternative. I also got feedback on other fora that RF might also be a good option to consider. Now knowing that price also can be lot lower if procured from the right place, there's more motivation to consider other options. Quite an insightful people, really apreciated. Back to the drawing board!