[sdiy] SPI comms - how fast is reasonable?

[grant at musictechnologiesgroup.com]

It's been a while since I've SPI (mostly I2C these days) but the
transfer speed of the bits isn't likely going to be your bottleneck.
It's going to be how fast the receiver can pick-up the data and react to
it. How long the main loop or ISR takes to get the data out, and then
process it, then ready for the next one.  If the SPI receiver is
hardware only (hardware state machine vs CPU executing firmware), then
you can really crank it up.

In your experiments is the communication one-way or is there some
response coming back?

GB