Motorola MVME1X7P manual Serial Port Interface

Models: MVME1X7P

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Programming Interfaces

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 Appendix C, Related Documentation 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 Chapter 3, PCCchip2 for detailed programming information.

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Motorola MVME1X7P manual Serial Port Interface