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How does SPI master know SPI slave is ready?

Fei Pan
Intellectual 620 points


Hi all,

I am trying to communicate between two DPS using SPI. One is master. Another is slave.

First, I will send data to the slave SPIDAT register and then send data to master SPIDAT register to initiate the transmission. The question is how the master know the valid data is ready in slave SPIDAT, not the dummy data, before it initiate the transmission?

Thanks

Fei

  • 0
    Guru 30330 points
    Fei,

    There is nothing in the SPI module that notifies the other end of data being ready. SPI is only as smart as the software you design around it. If you can spare an extra GPIO between F28069 and the Master SPI, you could create a simple status flag indicating that the slave is ready.

    For my own clarification, you are using a single SPI module to talk to two other DSPs. Not only are you switching between communication with two different DSPs, but you are also switching the mode of operation. This is sounds very complex. I would like to see how you are managing this when you have it complete, if it something you can share.

    Thanks,
    Mark
  • 0 in reply to Mark Labbato
    Guru 30330 points
    Fei,

    Have I answered your question? Please let me know so that we can close out this thread.

    -Mark