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Original question:

DRV8860: Daisy chain limitations and timing

DRV8860: Putting the device on a shared SPI bus

Andrew Chin82
Prodigy 160 points
Part Number: DRV8860

is it possible to put this DRV8860 on a bus with other SPI devices without any additional hardware intervention? From what I have tried (and it is shown in the datasheet as well), there are some caveats to this. It seems that there are some read outs that only respond to the clock cycling. That is, the chip will push out what is in a register at that given moment as long as the clock cycles. It seems that the Latch is only to control read inputs into the DIN line and has no bearing on DOUT? Is there a way to control this readout without any further hardware? If not, I guess I a limited to putting a controlled buffer (ie trisate) of some sorts on the DOUT line?

  • 0
    TI__Guru** 114905 points

    Hi Andrew, 

    The DRV8860's serial interface does not act as a standard SPI peripheral. Hardware intervention is required to use the DRV8860. Typically this means a few extra GPIO to create a serial interface compatible with the DRV8860.

    As you noted, there are special commands that require a specific number of clocks (Figure 17). This creates difficultly using a typical SPI interface.

    The DOUT acts as a shift register which can interfere with other peripherals on the bus.