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Communication of 12 LDC1001 at the same time

Stephan Scholz
Prodigy 120 points
Other Parts Discussed in Thread: LDC1001
Good day,

My goal is to have 12 LDC1001s working at the same time. I would like to transfer the 12  L_Data´s to Matlab (Mirroring).

Now my questions:
--> Is simultaneous communication possible or do you have to interrogate all sensors one after the other? 
-->Im also not sure how to differentiate the different L_DATA

Thanks for your help
Stephan
  • 0
    Prodigy 60 points

    Hi,

    Regarding your first question, SPI communication typically requires a chip select signal-

    So only 1 LDC1001 can be communicated with by the host system at a given time, unless
    it would provide 12 SPI masters all working in parallel.

    Regards,

    Johannes

  • 0
    Prodigy 65 points

    If you have 12 separate SPI masters, you can do the transfer in parallel.

    Otherwise, serially.

  • 0 in reply to johannes greiner
    Prodigy 120 points 
    Hi,


    Thank you for your answer. In my case the master is a Teensy 3.2 and the LDCs form the slave group. These slaves are connected through different SS.  So only 1 LDC1001 can communicate withe the Teensy? Or can i communicate in parallel, if all SS are Low?


    Regards,

    Stephan
  • 0 in reply to Stephan Scholz
    Prodigy 60 points

    Hi,

    Chip select is one-off. So for 12 SPI slaves you need 12 separate CS lines, only one active at a time.

    Not sure from where you have the concept that something could be done in parallel with SPI communication,
    or with serial communication in general. 


    A special exception might be to write to many SPI slaves in parallel, in which case of course all CS lines
    could be active at the same time. But this it non-SPI standard and would require to let the slave-output
    pins unconnected. Surly, not what you want to achieve.

    Regards,

    Johannes

  • 0 in reply to Stephan Scholz
    Prodigy 60 points

    HI again,

    How far are your 12 LDC devices set apart in your sensor setup?

    Keep in mind, that SPI in meant for short transmission distances only.
    Especially when using higher frequencies, as it seems your planned setup needs
    high bandwidth. 

    Regards,

    Johannes

  • 0 in reply to johannes greiner
    Prodigy 120 points

    ah thank you very much for your effort,
    I had taken into account that the shortest possible lines should be used for the SPI interface. 
    I will then query the slaves one after the other with a certain delay. Thank you

  • 0 in reply to Stephan Scholz
    TI__Genius 17690 points

    Hello, 

    It seems Johannes has covered this very well. Thank you Johannes. 

    To address differentiating the L_DATA, this would just be done by your microcontroller or Matlab script depending on how you are reading in and transferring the data. 

    Best Regards,