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SPI buffer writing 5x16

Mojo
Expert 1570 points

Hi,

I've always been using the SPI buffer with 4x16 bit writings.

However, it crossed my mind whether it will be possible to do 5x16 bit writing at once.

I think that since the first write is going directly do SPIDAT register, Then I still have 4x16 of the FIFO...

Do you think it's possible to write 5x16 bit at once ?

thanks

  • 0
    Guru 192875 points

    Hi Mojo,

    Which controller are you talking about?

    For F28027 its:

    For F28335 its:

    Regards,

    Gautam

  • 0 in reply to Gautam Iyer
    Expert 1570 points

    Hi,

    I was talking about the Piccolo series. I'm working on 28069.

    But I think this also applies to the Delfino, only instead of 5x16 you'll have 17x16 ....

    Will it be possible to write 5 times one after the other to SPITXBUF ? maybe some NOP instructions are needed before SPITXBUF transfers the first word to SPIDAT ?

    Basically my question comes because I need to output 5x16 data from an interrupt, and don't want to wait for next cycle to output the fifth word...

    thanks

  • 0 in reply to Mojo
    Guru 192875 points

    Hi Mojo,

    I don't think you'll be able to achieve 5x16 from a 4x16 FIFO available in F28069 MCU. You'll have to wait for the next cycle to output the fifth word. If you try to do the same, I guess the FIFO would overflow thus eliminating the fifth word. Do check and let me know what your experience is!

    Regards,

    Gautam

  • 0 in reply to Gautam Iyer
    Expert 1570 points

    Gautam,

    I cannot check it since I don't have the kit yet... If you have one, can you run a quick check ?

    My assumption is that the first word is transferred immediately to SPIDAT. So after the first write to TXBUF, the FIFO is still empty, right ?

    Can any TI employee answer this ?


    Thanks a lot