Motorola MBX Series, Installation And Use Manual

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5-14 Computer Group Literature Center Web Site
Functional Description
5
Hardware initializes the two serial ports as COM1 and COM2 with ISA
I/O base addresses of $3F8 and $2F8 respectively. This default
configuration also assigns COM1 and COM2 to interrupt request lines
INT4 and INT3 respectively in the PCI/ISA bridge controller. You can
change the default configuration by reprogramming the I/O controller. For
programming information, refer to the PCI and ISA bus discussions in the
MBX Series Embedded Controller Version B Programmer’s Reference
Guide and to the vendor documentation for the I/O controller.
The MBX can derive its console/terminal interface from either of two
sources: the COM1 port in the I/O controller, or the SMC1 port in the
processor chip. By default, standard configurations use the I/O controller’s
COM1. Because entry-level configurations of the MBX board are not
equipped with the I/O controller, they use SMC1 on the processor by
default. You can also select one port or the other by setting control bits in
control register #1 (refer to the MBX Series Embedded Controller Version
B Programmer’s Reference Guide for details).
Parallel Port
The bidirectional parallel port found in MBX series embedded controllers
may take one of two forms depending on the board configuration
determined at the time of manufacture: a partial IEEE 1284 parallel port
with both host and peripheral capability, residing in the processor; or a full
IEEE 1284 parallel port with only host capability, implemented with the
I/O controller available in standard configurations of the board. In either
case, all parallel I/O interface signals are routed to parallel port header J13.
To select between host or peripheral mode, you set control registers in the
processor (refer to the MBX Series Embedded Controller Version B
Programmer’s Reference Guide for details). In peripheral mode, the
MPC8xx itself acts as a Centronics printer interface as it receives data from
some other master in the system.
The signals not implemented in the partial IEEE 1284 implementation are
AUTOFD#, INIT#, and SEL_IN#. The full IEEE 1284 implementation
supplies those signals at the expense of the peripheral-mode capability. For
programming information, refer to the parallel port discussions in the MBX
Series Embedded Controller Version B Programmer’s Reference Guide
and to the vendor documentation for the I/O controller.