Cirrus Logic CS8900A - Manual (Page 44)

44 DS271F5
CS8900A
Crystal LAN™ Ethernet Controller
CIRRUS LOGIC PRODUCT DATASHEET
4.3 Bus Interface Registers
4.3.1 Product Identification Code
(Read only, Address: PacketPage base + 0000h)
The Product Identification Code Register is located in the first four bytes of the PacketPage (0000h to 0003h). The
register contains a unique 32-bit product ID code that identifies the chip as a CS8900A. The host can use this num-
ber to determine which software driver to load and to check which features are available.
Reset value is: 0000 1110 0110 0011 0000 0000 000X XXXX
The X XXXX codes for the CS8900A are:
Rev B: 0 0111
Rev C: 0 1000
Rev D: 0 1001
Rev F: 0 1010
4.3.2 I/O Base Address
(Read/Write, Address: PacketPage base + 0020h)
The I/O Base Address Register describes the base address for the sixteen contiguous locations in the host system's
I/O space, which are used to access the PacketPage registers. See Section 4.10 on page 75. The default location
is 0300h.
After reset, if no EEPROM is found by the CS8900A, then the register has the following initial state. If an EEPROM
is found, then the register's initial value may be set by the EEPROM. See Section 3.3 on page 19.
Reset value is: 0000 0011 0000 0000
4.3.3 Interrupt Number
(Read/Write, Address: PacketPage base + 0022h)
The Interrupt Number Register defines the interrupt pin selected by the CS8900A. In a typical application the follow-
Address 0000h Address 0001h Address 0002h Address 00003h
First byte of EISA registration
number for
Crystal Semiconductor
Second byte of EISA
registration number for
Crystal Semiconductor
First 8 bits of
Product ID number
Last 3 bits of the Product ID
number (5 “X” bits are the
revision number)
Address 0021h Address 0020h
Most significant byte of I/O Base Address Least significant byte of I/O Base Address
Address 0023h Address 0022h
00h
Interrupt number assignment:
0000 0000b= pin INTRQ0
0000 0001b= pin INTRQ1
0000 0010b= pin INTRQ2
0000 0011b= pin INTRQ3
0000 01XXb= All INTRQ pins high-impedance