[sdiy] SPI comms - how fast is reasonable?

[Tom Wiltshire]

Grant,

No, the comms is one-way. I want a main CPU to send parameter data  
and note on/offs to the synth voice(s). Assuming I can be reasonably  
sure the data will get through ok (no reason why it shouldn't,  
right?) then I don't need anything coming back. If not, I might need  
a "data not received correctly" message going the other way, but that  
is to be avoided if at all possible.
Also, I hear what you're saying about the bottleneck being software  
not the actual transmission speed. I'll do what I can in that regard.

What are your reasons for using I2C not SPI? Isn't SPI faster? Am I  
making the wrong choice?

Thanks,
Tom

On 5 Mar 2010, at 18:22, grant at musictechnologiesgroup.com wrote:

> 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?