Hi All,

I am currently involved in an embedded linux project using the Motorola
MCF5272 microprocessor running uClinux.  I need a total of four serial ports
on the product and have decided to use the fairly industry standard Dual
UART IC from national semiconductor the PC16C552.  My problem is due to the
limited amount of GPIO ports available for external hardware interfacing.
The PC16C552 DUART has a Chip Select pin, as many peripheral IC's do.  As
this will be the only device attached to the GPIO ports of the
microcontroller I was hoping to simply tie this pin low and keep the chip
selected at all times.  I have been through the datasheet over and over and
can't quite acertain if this will be possible according to the timing
waveforms supplied by national.  Does anyone have any experience in this
area and could advise me on whether it would be a good idea to keep CS low
(ie. Active).  I know with certain peripheral devices the return of CS to
the idle state indicates that a transmission is finished but these were all
serially interfaced devices unlike the PC16C552.  Here is the address of the
datasheet if you wish to peruse it
http://www.national.com/ds.cgi/NS/NS16C552.pdf I have and am still unsure of
what to do.

Thanks in advance,
Damien Cahill.

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