Serial port interface, Serial port interface -13 – Motorola MVME1X7P User Manual
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Programming Interfaces
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1
Serial Port Interface
The CD2401 serial controller chip (SCC) is used to implement the four
serial ports. The serial ports support the standard baud rates (110 to 38.4K
baud). The four serial ports differ in function because of the limited
number of pins on the P2 I/O connector:
❏
Serial port 1 is a minimum-function asynchronous port. It uses
RXD, CTS, TXD, and RTS.
❏
Serial ports 2 and 3 are full-function asynchronous ports. They use
RXD, CTS, DCD, TXD, RTS, and DTR.
❏
Serial port 4 is a full-function asynchronous or synchronous port. It
can operate at synchronous bit rates up to 64 k bits per second. It
uses RXD, CTS, DCD, TXD, RTS, and DTR. It also interfaces to
the synchronous clock signal lines. Refer to
for drawings of the serial port interface
connections.
All four serial ports use EIA-232-D drivers and receivers located on the
main board, and all the signal lines are routed to the I/O connector. The
configuration headers are located on the main board and may be on some
transition boards. An external I/O transition board is necessary to convert
the I/O connector pinout to industry-standard connectors.
Note
The MVME1X7P board hardware ties the DTR signal from the
CD2401 to the pin labeled RTS at connector P2. Likewise, RTS
from the CD2401 is tied to DTR on P2. Therefore, when
programming the CD2401, assert DTR when you want RTS, and
RTS when you want DTR.
On both MVME167P and MVME177P boards, the interface provided by
the PCCchip2 allows the 16-bit CD2401 serial controller chip to appear at
contiguous addresses. Accesses to the CD2401, however, must be 8 or 16
bits. 32-bit accesses are not permitted. Refer to the CD2401 data sheet and
to
for detailed programming information.