I am having trouble getting 4 MFRC522 readers over CAT6 cable. The program is from Alastair's PlayfulTech on patreon. (https://www.patreon.com/posts/object-placement-15708301). However the RFID is not working over CAT6 cable (even over a short cable).
Has anyone gotten MRFC522 to work over CAT6 twisted pair before? Any suggestions?
It is possible to have a cable with the wrong pinning (crossover, straight through, and more).
Right! MAtch the color codes of the wires, not the pins of a connector. Google can tell you the colors for the pairing of the twisted wires.
The Cable is terminated in standard B format (Orange-White/Orange/Green-White/Blue/Blue-White/Green/Brown-White/Brown. Is that not what you are referring to. Then Pin one (orange-white) goes to GND, Pin two (orange) goes to 3.3V and so on.
Yes, but, did you check for continuity between the corresponding pins at each end of the cable?
Yes, I put the cable through my normal tester and certifier, the MFRC522 does light the red led. But appears to initalize, but will not send any card data.
Are you using the spi bus or the I2C buss connection?
Arduino mega with Ethernet shield on SPI bus using alternative SPI pins.
Ok. Are you pairing each SPI signal line with a ground wire to make the correct twisted pair? Are taking care of the difference between the 5 volts on the mega pins and the 3.3 volts on the MRF pins?
@Paul_KD7HB, I am not certain how I would go about that. At present, the wiring is this:
Orange-White - 3.3V
Orange - RST
Green-White - GND
Blue - IRQ (not used)
Blue-White - MISO
Green - MOSI
Brown-White - SCK
Brown - SDA
Do you have a better configuration?
Yes, as I wrote, pair each signal with it's matching ground.
Brown - SDA
Brown-white, ground
Green - MOSI
Green - white, ground
Blue - MISO
Blue - white, ground
Orange - 3.3 volt
Orange - white, ground ground for power
Any other configuration is destined for trouble, and means you need a cable with more twisted pairs.
So I don't need the SCK or Reset?
It's your project look at the specifications and use of those and tell me. It may be you need more twisted pairs than cat5/6 has.
How long is the cable?
Try this:
Brown - SDA
Brown-white, ground
Green - MOSI
Green - white, ground
Blue - MISO
Blue - white, 3V3
Orange - SCL
Orange - white, 3V3
The actual choice of colour for each signal is irrelevant and which 2 whites are ground and which 2 are 3V3 is also irrelevant. Probably should have 0μ1 ceramic capacitor at each end between ground and 3V3.
Lowering the clock frequency will also increase your chances of success.
I don't promise this will work but it's worth trying. As far as signals are concerned supply voltage and ground are pretty much the same thing.
This topic was automatically closed 180 days after the last reply. New replies are no longer allowed.