36 SBC330 3U VPX Single Board Computer
Publication No. SBC330-0HH/3
The
table
below
shows
the
divisors
used
for
some
commonly
used
baud
rates
and
the
percentage
error
associated
with
the
use
of
an
integer
divider.
NOTE
The percentage error will increase significantly at higher baud rates. Different divisors will be
required if a different MPX bus frequency is used.
The
serial
ports
are
driven
by
Intersil
ISL4223
bus
transceivers.
The
transceivers
are
capable
of
up
to
250
Kbps
operation.
The
performance
of
these
ports
is
limited
by
the
throughput
capability
of
the
software
driver.
COM1
and
COM2
are
available
through
the
P1
and
P2
VPX
connectors.
The
COM2
port
is
used
for
the
serial
access
programming
of
the
BMM
–
currently
an
in
‐
house
operation.
NOTE
For the default shippable VxWorks BSP, the serial rate is 9600 kBaud. Although the serial ports can
operate at much higher frequencies, this is a GEIP standard because all Data Terminal equipment
can operate at this speed. Speed mismatches between the terminal and the SBC330 can have the
effect that it appears as board has not booted.
5.6.3 USB
An
NEC
μ
PD720101
device
provides
four
USB
ports
on
the
SBC330
and
is
connected
to
the
PCI
bus.
The
device
is
capable
of
operation
at
USB
standard
low
‐
,
full
‐
or
high
‐
speed.
The
device
contains
two
OHCI
controllers
(for
USB1.1
operation)
and
one
EHCI
controller
(for
USB2.0
operation).
Alternate
ports
use
a
different
OCHI
controller
for
USB1.1
operation
and
ports
arbitrate
to
share
the
EHCI
controller
for
USB2.0
operation.
The
internal
functions
are
configured
as
follows:
An
in
‐
line
common
‐
mode
choke
is
fitted
to
the
USB
I/O
pairs
to
filter
high
frequency
noise.
This
improves
signal
integrity
and
helps
to
reduce
EMI
emissions.
The
USB
ports
are
available
on
the
P1
and
P2
connectors.
Table 5-9 Baud Rate Divisors
Target Baud
Rate
MPX Bus
Frequency
(MHz)
Divisor
(Decimal)
Divisor (Hex)
Actual Baud
Rate
Error (%)
9600
400
2604
0A2C
9600.61
0.0064
19200
400
1302
0516
19201.23
0.0064
38400
400
651
028B
38402.46
0.0064
56000
400
446
01BE
56053.81
0.0961
128000
400
195
00C3
128205.13
0.1603
Table 5-10 USB Device Functions
Controller
PCI Function No
Interrupt
OHCI 0
0
INTA~
OHCI 1
1
INTB~
EHCI
2
INTC~