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TMS320F28035: SPI Daisy Chain

Luca Guarda
Prodigy 50 points
Part Number: TMS320F28035


Hy,

in my application i want to use DSP TMS320F28035 as a SLAVE in a Daisy chain structrure with multiple DSP.

Is possible to use this structure with this DSP? SPIDI can be shifted in a SPIDO as in a generic Slave SPI (for example ADconverter).

The question concerns the SPIDI / SPIDo registers, can they be used as shift register in which the data present in SPIdi at each clock edge is loaded on SPIDO?

Thanks

  • 0
    TI__Mastermind 25210 points

    Hi Luca,

    The F28035 device only has four pins for SPI communication,

    SPISOMI: SPI slave-output/master-input pin

    SPISIMO: SPI slave-input/master-output pin

    SPISTE: SPI slave transmit-enable pin

    SPICLK: SPI serial-clock pin

    The diagram you have provided shows a clk in and a clk out. Would you mind elaborating on this connection you plan to use?

    Best Regards,

    Marlyn

  • 0 in reply to Marlyn Rosales Castaneda20
    Prodigy 50 points

    First solution, and more simple solution, is a slave implementation using only spiclki (input) where the spiclko is the same hardware signal sent at second slave, this to have same delay in the clock and data signal.  spisomi is the data out. Spisimo is the data in and spiste is a CS

    In a slave, i don't want to use the second solution with two spi A and B with 2 clk.

  • 0 in reply to Luca Guarda
    TI__Mastermind 25210 points

    Luca,

    Luca Guarda said:
    The question concerns the SPIDI / SPIDo registers, can they be used as shift register in which the data present in SPIdi at each clock edge is loaded on SPIDO?

    This can be done but will depend on the clk speed you want to run from the master and how fast the data coming in can be written back out. A few things I've seen others do if they run into issues is slow down the SPI CLK from the master side or make the SPI CLK go low for a short amount of time (if possible) to allow for the data to be written to the SPISOMI line.

    Best Regards,

    Marlyn