Connect STM32 Discovery board with Cyton

abhinandanaggarwalabhinandanaggarwal Zurich
in Cyton
I want to connect my STM32 Discovery Microcontroller board with the Cyton board and I am not sure if we can do it via the SPI pins given for the daisy chain module. I want to extract data from the SD card or stream data directly into my Discovery board via those pins and do some processing on the data. Can I do this arrangement...???

Thanks in advance.


Comments

  • wjcroftwjcroft Mount Shasta, CA
    You might look into what is called USB Host mode or USB-OTG for the Discovery,


    For example, the Linux that runs on Raspberry has this capability. Thus if that would work for Discovery you may be able to plug the Cyton dongle into the usb port. 

    ----

    However your question sounds like you are trying to drive Daisy SPI from Discovery. Not recommended. Power isolation is crucial, you don't want to risk mains power glitches reaching your brain(!) And Cyton mainboard cannot be driven like this obviously, it's SPI master.
  • abhinandanaggarwalabhinandanaggarwal Zurich
    Thanks for the reply...

    Let me rephrase the question. I am trying to send the data from the Cyton board to my Discovery board for external signal processing. I would like to program the Cyton in such a way that it transfers the data to the Discovery board through the Daisy SPI connection. Same as it was done for the Daisy module, but instead of reading from Daisy, the Cyton would send the data to the Discovery board.  The Discovery will be acting as a slave here.
    Is there any complication involved or is there anybody who has tried this kind of arrangement before ?

    Thanks in advance.

  • wjcroftwjcroft Mount Shasta, CA
    What you are considering would be problematic and there are also the safety issues mentioned previously. Did you look into using the Cyton dongle in USB Host mode? This is how Raspberry talks to the Cyton. Remember that SPI uses a master / slave relationship. In this case BOTH Cyton and Discovery are by default masters, so I don't believe what you are looking for can work, even beyond safety aspects. There is no firmware support for this in the Cyton code.

    There are also some threads regarding "wired usb" with an opto isolator, for example, see,


    The optoisolation here gives you the safety factor. But again, this requires using the Discovery usb port in host mode attached to an FTDI usb serial interface. Does Discovery allow external usb serial?

  • wjcroftwjcroft Mount Shasta, CA
    Remember that the Cyton dongle IS ALSO a usb serial port. So try connecting to that serial port first. The link above shows that Discovery does support "virtual COM ports", in other words, serial usb.

    The "wired usb" is really only helpful if you are looking for faster sample rates. If you just want the default rates, go with the Cyton dongle.


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