Motorola MVME197LE manual Battery Backup RAM and Clock, VMEbus Interface, Interfaces

Functional Description

DRAM is not disabled by a local peripheral bus reset. Refer to the DCAM and ECDM chapters in the MVME197LE, MVME197DP, and MVME197SP Single Board Computers Programmer’s Reference Guide for detailed programming information.

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Battery Backup RAM and Clock

The MK48T08 RAM and clock chip is used on the MVME197LE. This chip provides a time of day clock, oscillator, crystal, power fail detection, memory write protection, 8KB of RAM, and a battery in one 28-pin package. The clock provides seconds, minutes, hours, day, date, month, and year in BCD 24-hour format. Corrections for 28-, 29-, (leap year) and 30-day months are automatically made. No interrupts are generated by the clock. The MK48T08 is an 8-bit device; however the interface provided by the PCCchip2 supports 8-, 16-, and 32-bit accesses to the MK48T08. Refer to the PCCchip2 chapter in the MVME197LE, MVME197DP, and MVME197SP Single Board Computers Programmer’s Reference Guide and to the MK48T08 data sheet for detailed programming information.

VMEbus Interface

The local peripheral bus to VMEbus interface, the VMEbus to local peripheral bus interface, and the local-VMEbus DMA controller functions on the MVME197LE are provided by the VMEchip2. The VMEchip2 can also provide the VMEbus system controller functions. Refer to the VMEchip2 chapter in the MVME197LE, MVME197DP, and MVME197SP Single Board Computers Programmer’s Reference Guide for detailed programming information.

I/O Interfaces

The MVME197LE provides onboard I/O for many system applications. The I/O functions include serial ports, a printer port, an Ethernet transceiver interface, and a SCSI mass storage interface.

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). Serial port 4 also supports synchronous modes of operation.

The four serial ports are different functionally because of the limited number of pins on the 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

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