I am trying to communicate with an MFRC522 device using my RPi 4B and the SPI interface. My application is written in Java and communicates under NetBeans with the RPi as a remote platform. The application itself runs on the RPi. At present, I am unable to read from any device register on the MFRC522 since the Pi4J and Spi Java libraries do not provide an spi.transfer command, the only means I can see of reading from the device.
I can see from some examples written in Python that it is possible using the transfer command seemingly available from the Python libraries, but the same command is unavaileble in Java.
I have also seen a Java application using the spi.transfer command. This seems to be possible using the com.google.android.things.pio.SpiDevice library, but I cannot find where a copy of this library exists to download a Jar file. I have also seen a comment that implies that Android Things is not supported on RPi4, but only on RPi3. Can anyone confirm this, or suggest how I could read using SPI on RPi4