Usb - GE SBC330 3U VPX Hardware Reference Manual

36 SBC330 3U VPX Single Board Computer
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.
Table 5-9 Baud Rate Divisors
MPX Bus
Target Baud
Frequency
Rate
(MHz)
9600 400
19200 400
38400 400
56000 400
128000 400
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 μPD720101 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:
Table 5-10 USB Device Functions
Controller PCI Function No
OHCI 0 0
OHCI 1 1
EHCI 2
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.
Divisor
Divisor (Hex)
(Decimal)
2604 0A2C
1302 0516
651 028B
446 01BE
195 00C3
Interrupt
INTA~
INTB~
INTC~
Actual Baud
Error (%)
Rate
9600.61 0.0064
19201.23 0.0064
38402.46 0.0064
56053.81 0.0961
128205.13 0.1603
Publication No. SBC330-0HH/3