Crystal LAN CS8920, Техническое справочное руководство, Страница: 40 / 67

AN84REV1 40
CS8920 Technical Reference Manual
Typically, transmission is enabled by the
MAC driver during its initialization stage.
3.2.2.4 BootPROM Considerations
In all cases, if a BootPROM is installed to
the CS8920 adapter, the adapter should be
activated from the Reset Configuration
Block. In legacy systems, the BootPROMs
base address and address mask must also
be loaded into PacketPage registers from
the Reset Configuration Block as shown in
Table 3.4.
Addr Word Description
... ... ...
07h 2340 3 words into PacketPage 340h
08h 800Ch Base Address = 0C8000h
09h FF00h Use address lines [23:16], 8-bit device
0Ah 00C0h Use address lines [15:14]
0Bh 0330h 1 word to PacketPage 330h (RegActivate)
0Ch 0001h Activate Adapter
0Dh XX00h Checksum on 28 bytes
Table 3.4. Configuration of BootPROM
from Reset Configuration Block.
If the adapter is installed in a PnP system
with an autoconfiguring BIOS, the
BootPROM address and mask will be
assigned during the PnP configuration
sequence and should not be loaded from the
Reset Configuration Block.
3.2.2.5 Performance Considerations of
Reset Configuration Block
Software resets may occur frequently and
performance will be enhanced if chip re-
initialization takes as little time as possible.
Therefore, since EEPROM readout takes
approximately 25
µ
sec. per word, the
length of the Reset Configuration Block
should be kept to a minimum.
3.3 Format of the Driver
Configuration Block
The region of EEPROM addressed as word
addresses 1Ch to 34h is referred to as the
Driver Configuration Block. It is used by
the MAC driver to determine adapter
configuration information such as the
unique IEEE physical address , hardware
version, media capabilities, and bus
configuration (IRQ, DMA, and memory).
This region is called the Driver
Configuration Block.
Table 3.2 defines the format for the Driver
Configuration Block required for use with
MAC drivers provided by Crystal. Crystal
recommends all fields be initialized to their
default values before shipping the adapter.
Default values for each field are indicated
in sections 3.3.1 through 3.3.13. All
reserved fields should be set to zero.
Note: words 30h - 34h are also used as by
PnP as the Serial Identifier block for the
adapter.