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SPI wont idle low. STM32F103VET6

Neil Radnitz

Hi.

I have probably overlooked something very basic here. For some reason my SPI brings up a mode fault, just after I enable the peripheral whenever I try get get it to idle low.

If I idle high or change any of the other switches (polarity, baud etc) it works fine.

I don't suppose anyone has come across this problem?

Parents
  • 0 in reply to Cpt. Vince

    Thanks for the feedback.

    I actualy found the problem just after I sent this thread. As I said origionaly I probably overlooked something.

    Section 18.3.8 on page 423 of the reference manual states "Master Mode fault occurs when the master device has its NSS pin pulled low (in hardware mode) or SSI bit low (in software mode), this automaticaly sets the MODF bit".

    We are the using the SPI to communicate to multiple devices so the NSS pin is just floating in this project. I made the incorrect assumption that keeping it low in my port setup would be sufficient.

    I have adjusted the NSS pin to read high and it now works on low polarity.

    I am still worried about this, I would think from the statement above it should not work in either polarity states. I am reading further to make sure there isn't something else I have missed.

Reply
  • 0 in reply to Cpt. Vince

    Thanks for the feedback.

    I actualy found the problem just after I sent this thread. As I said origionaly I probably overlooked something.

    Section 18.3.8 on page 423 of the reference manual states "Master Mode fault occurs when the master device has its NSS pin pulled low (in hardware mode) or SSI bit low (in software mode), this automaticaly sets the MODF bit".

    We are the using the SPI to communicate to multiple devices so the NSS pin is just floating in this project. I made the incorrect assumption that keeping it low in my port setup would be sufficient.

    I have adjusted the NSS pin to read high and it now works on low polarity.

    I am still worried about this, I would think from the statement above it should not work in either polarity states. I am reading further to make sure there isn't something else I have missed.

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