>
> > If you have several devices on the bus, it is of course possible to
> > write to one whilst reading from another which saves a few cycles doing
> > two separate operations.
>
> I don't think that you can do that with SPI. A device that is not selected
> should have its pins tristated so they don't load the bus.
>
Yes you can do this simultaneous xmit/rcv scheme. I've done it many times.
While one SPI device (ex. an A/D chip) is transmitting data in on the SDI
pin, another device (ex. a D/A) can be receiving data from the SDO pin. Both
devices are enabled at the same time - one is receiving one is transmitting.
Works great.

-Mark



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