Hello,
We have rigged up 2 digital pots., analog devices AD8403.  Each
device has a shift register, which enables daisy chaining.  Each
device contains 4 pots which all work as expected.  Each pot. is
addressed via the serial input.  However on inspection of Serial out
of a device is not a delayed version of its  input, as might be
expected from a conventional shift register.
Output data appears spikey ie not clean switching of logic levels and
does not go down to zero.

Andy Farrar
andrew.farrar@port.ac.uk