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MSP432E401Y: Communications

Daniel Nanto
Intellectual 290 points
Part Number: MSP432E401Y
Other Parts Discussed in Thread: DRV8462

Good morning,

I am working on a project and would really appreciate some advice. I have a QT application that runs on a Raspberry Pi 4. The Raspberry Pi 4 is using almost all of its GPIO for other tasks like temperature monitoring. So, in the interest of offloading some of the workload, I am sending the motion data in the form of "pseudo G-code" to an MSP432E401Y. The MSP432E401Y then needs to control 4-6 DRV8462 devices via SPI. The MSP432E401Y also needs to be able to send information back upstream to the RPi4.

I have two main questions:

  1. If you were designing this system, which form of communication would you use to send this "G-code" from the RPi4 to the MSP432E401Y?
  2. Would SPI be possible in this situation? Could the MSP432E401Y simultaneously be a "child" (aka slave) to the RPi4, and a "parent" (aka master) to the DRV8462?

I would really appreciate your help!

Thank you,

Dan Grin

  • 0
    TI__Guru**** 190806 points

    Hi,

    Daniel Nanto said:
    • If you were designing this system, which form of communication would you use to send this "G-code" from the RPi4 to the MSP432E401Y?

    This is really a very application dependent question only someone who has the knowledge in the overall systems will be able to answer. Do you need to send this G-code constantly between RPi4 and  MSP432E4 or this is a one time event? How large is this G-code? How does MSP432E decode this G-code and then translate into commands to send to DRV via SPI? How fast do you want the DRV to respond to these commands? You need to answer many of the questions yourself. I have no knowledge into your overall systems and requirements and I can't help you which communication is suitable.  All I can say is normally SPI operates at higher bandwidth than others. 

    Daniel Nanto said:
    Would SPI be possible in this situation? Could the MSP432E401Y simultaneously be a "child" (aka slave) to the RPi4, and a "parent" (aka master) to the DRV8462?

    Yes, if you use two SPI modules with one acting as a slave to receive data from RPi4 and another SPI acting as a master sending data to DRV. 

  • 0 in reply to Charles Tsai
    Intellectual 290 points

    Thank you for your answer about the SPI modules!

    I can appreciate that I may not have provided enough information to enable you to feel comfortable making a design suggestion. I apologize!

    The pseudo G-code is sent line by line. Essentially, it provides the desired axes coordinates and the travel-rate each time the machine needs to travel to a new location. It really only sends information once every second or so. 

    Do you think SPI might be appropriate in this situation?

  • +1 in reply to Daniel Nanto
    TI__Guru**** 190806 points

    Hi Daniel,

    Daniel Nanto said:
    The pseudo G-code is sent line by line. Essentially, it provides the desired axes coordinates and the travel-rate each time the machine needs to travel to a new location. It really only sends information once every second or so.

    Are you sending one line of G-code every second or an entire G-code every second? If you are sending just several bytes (assuming one line of G-code) of data every second then you can consider UART which uses just two pins rather than 4 pins as for SPI.  If you are sending an entire G-code then I will choose SPI. 

  • 0 in reply to Charles Tsai
    Intellectual 290 points

    I am only sending a line every second. Thank you for the advice! I appreciate your time.