Re: [Uisp-dev] RFC: use uisp as terminal/pty

[jepler]

I think that some other AVRs may have support for communication over
this bus with a couple of byte-at-a-time registers, in which case this
would be a nice idea.  However, I'm just not very familiar with those
parts.  For example, in the ATMEGA8 the "SPI" port is controlled by the
registers SPCR, SPSR and SPDR.  This appears to require use of an
additional pin, SS/ (maybe this pin can simply be tied low?  Doesn't
seem like much of a 3-wire bus if it requires 4 pins)

The AVR I'm most familiar with is the at90s2313, an older 20-pin part.
On it, there's no built-in support for MOSI/MISO/SCK communication---
instead, it would be necessary to poll SCK and clock the bits in/out of
the ports manually.  You might be able to do a little better by tying
SCK and INTx  together, but that's still one interrupt per bit.

Jeff

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