[hpsdr] ALEX - Call for Comments - II

[Michael Ardai]

> 2.) Control...
> This is a receiver front end preselector.  I would prefer
> to not have any in-band oscillators, clocks, or noisy high speed
> buses appear on the card.  For that reason I would propose that
> this be a "dumb" slave card, controlled by a three wire SPI bus,
> which would be filtered upon entrance.  I2C would also work.
> Phil H wanted I2C, I personally prefer SPI, Lyle seems to like SPI.

CPLD does not necessarily imply high-speed clocks; you can use them
as configurable combinatorial logic as well.  SPI certainly can
be done this way (and it can easily handle non-multiples of 8 bits
if needed).  It has been a while since I looked at I2C to see if
a clock other than the i2c clock is needed.
/mike


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