Crystal LAN CS8920, Техническое справочное руководство, Страница: 53 / 67

AN84REV1 53
CS8920 Technical Reference Manual
3.5 Programming and Initializing
the EEPROM
The contents of the EEPROM may
either be pre-programmed in an stand-
alone EEPROM programmer or
programmed after installation through
the CS8920’s serial interface.
When programming an EEPROM for
the first time via the CS8920's serial
interface after the EEPROM has been
installed on the adapter, the CS8920's
auxiliary key must be used.
On reset, if the Reset Configuration
Block's checksum is invalid ( typically
the case with a new EEPROM
installation), the CS8920 performs an
EEPROM reset. This reset reloads all of
the CS8920's PacketPage registers with
their default values, thereby leaving the
CS8920 inactive. In this state, all
communication with the CS8920 using
normal IO is disabled. Further, the
CS8920 will no longer respond to the
standard PnP initiation key.
However, writing the CS8920-specific
auxiliary initiation key to the PnP write-
data port after an EEPROM reset will
enable the CS8920 to respond to
standard PnP commands. The adapter is
then configured with an IO base and
made active by writing the appropriate
commands and data to the PnP write-
data port. Once the CS8920 has been
made active and the IO base address is
assigned via the PnP interface, the
EEPROM may be programmed in the
usual manner. Refer to the CS8920 Data
Sheet for more information on
programming the EEPROM via the
CS8920’s serial interface.
WARNING: The CS8920 will respond
to the auxiliary key only after an
EEPROM reset has occurred. In
addition, the CS8920 will not respond to
the auxiliary initiation key if the PnP
functions of the CS8920 are disabled.
Therefore, it is important to ensure that
the CS8920 is explicitly activated from
the Reset Configuration Block whenever
a valid Reset Configuration Block is
present and the CS8920's PnP functions
are disabled. Failure to do so will make
it impossible to communicate with the
CS8920 and to re-program the
EEPROM without first removing it from
the adapter and installing in another
adapter or stand-alone EEPROM
programming device.
3.5.1 Maintaining EEPROM
Configuration Data
Crystal provides two utilities for
maintaining the configuration
information stored in the EEPROM.
One is designed to be used by OEMs to
initialize the EEPROM’s contents before
shipping to the end-user (OEM
EEPROM Programming Utility).
The other is a DOS-based Setup and
Installation utility run by the end-user at
the time the adapter is installed. The
Setup and Installation utility allows the
end-user to configure the adapter for a
specific system. Refer to Section 4.2 for
more information on the DOS Setup and
Installation utility.
The OEM is left to determine the best
procedure for programming EEPROMs