On 31/05/2011 21:29, Steve Wiseman wrote:
> David: Yes, the lack of SPIs is a bit of a concern. We do have a
> decent pile of i2c, though, for slow IO. SPI is only really necessary
> for fastish ADCs or audio, both of which I think are adequately
> served.

For what it's worth, I keep discovering needs for more SPI stuff every
time I design something. More and more little widgety devices (ADC,
displays, and so on) expect an SPI connection. I2C and its
license-avoiding derivatives don't seem to be as popular any more, and
also have addressing annoyances.

All these SPI devices have chip-selects, though, so I don't see a strong
need for multiple buses. Just lots of space for chip selects.

I've also found that SPI-hardware-supported-automated chip selects
rarely do quite the Right Thing, especially for devices with
variable-length transfers and the pathological Nat Semi devices with
bidirectional data pins. I'd therefore vote for generic GPIOs as chip
selects which kernel device drivers can do sensible things with, and we
shouldn't get hung up on trying to make the auto chip selects available.

Chris
-- 
Chris Jones - chris@martin-jones.com
Martin-Jones Technology Ltd c/o Element Energy Ltd
Twenty Station Road, Cambridge, CB1 2JD, UK
Phone +44 (0) 1223 655611 Fax +44 (0) 870 112 3908