Motorola MVME1X7P - Manual (Page 41)

Programming Interfaces
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1
Ethernet Interface
The MVME1X7P uses the Intel 82596CA LAN coprocessor to implement
the Ethernet transceiver interface. The 82596CA accesses local RAM
using DMA operations to perform its normal functions. Because the
82596CA has small internal buffers and the VMEbus has an undefined
latency period, buffer overrun may occur if the DMA is programmed to
access the VMEbus. Therefore, the 82596CA should not be programmed
to access the VMEbus.
Every MVME1X7P that is built with an Ethernet interface is assigned an
Ethernet Station Address. The address is $0001AFxxxxxx where xxxxxx is
the unique 6-nibble number assigned to the board (i.e., every MVME1X7P
has a different value for xxxxxx).
Each board has an Ethernet Station Address displayed on a label attached
to the VMEbus P2 connector. In addition, the six bytes including the
Ethernet address are stored in the configuration area of the BBRAM. That
is, 0001AFxxxxxx is stored in the BBRAM. At an address of $FFFC1F2C,
the upper four bytes (0001AFxx) can be read. At an address of
$FFFC1F30, the lower two bytes (xxxx) can be read. (Refer to the
BBRAM/TOD Clock memory map description in this chapter under
Battery-Backed-Up RAM and Clock for specifics.)
The MVME1X7P debugger firmware has the capability to retrieve or set
the Ethernet address. If the data in the BBRAM is lost, use the number on
the VMEbus P2 connector label to restore it.
The Ethernet transceiver interface is located on the MVME1X7P main
board, and the industry-standard DB15 connector is located on the
MVME712B transition board.
Support functions for the 82596CA LAN coprocessor are provided by the
PCCchip2 ASIC. Refer to the 82596CA user’s guide and to
Chapter 3,
PCCchip2 for detailed programming information.