CS8900-CQ3 Cirrus Logic, CS8900-CQ3 Datasheet - Page 22

• Manufacturer Part Number: CS8900-CQ3
• Description: Crystal LAN ISA Ethernet Controller
• Manufacturer: Cirrus Logic

* FFFFh is a special code indicating that there are no more words in the EEPROM.
CS8900A will not attempt to read configuration
data from the EEPROM.
3.4.3.5 Determining Number of Bytes in the Reset
Configuration Block
The low byte of the Reset Configuration Block
header is known as the link byte. The value of the
Link Byte represents the number of bytes of config-
uration data in the Reset Configuration Block. The
two bytes used for the header are excluded when
calculating the Link Byte value.
FIRST WORD in DATA BLOCK
FIRST GROUP of WORDS
SECOND GROUP of WORDS
THIRD GROUP of WORDS
CHECKSUM Value
22
Word Address
0Ch
0Dh
0Ah
0Bh
0Eh
0Fh
00h
01h
02h
03h
04h
05h
06h
08h
09h
10h
07
A120h
502Ch
E000h
000Dh
C000h
2020h
0300h
0003h
0001h
000Fh
0000h
000Fh
2158h
0010h
0000h
0000h
2800h
Value
Table 6. EEPROM Configuration Block Example
CIRRUS LOGIC PRODUCT DATA SHEET
Configuration Block Header.
The high byte, A1h, indicates a ‘C46 EEPROM is attached. The Link Byte,
20h, indicates the number of bytes to be used in this block of configuration
data.
Group Header for first group of words.
Three words to be loaded, beginning at 0020h in PacketPage memory.
I/O Base Address
Interrupt Number
DMA Channel Number
Group Header for second group of words.
Six words to be loaded, beginning at 002Ch in PacketPage memory.
Memory Base Address - low word
Memory Base Address - high word
Boot PROM Base Address - low word
Boot PROM Base Address - high word
Boot PROM Address Mask - low word
Boot PROM Address Mask - high word
Group Header for third group of words.
Three words to be loaded, beginning at 0158 in PacketPage memory.
Individual Address - Octet 0 and 1
Individual Address - Octet 2 and 3
Individual Address - Octet 4 and 5
The high byte, 28h, is the Checksum Value. In this example, the check-
sum includes word addresses 00h through 0Fh. The hexadecimal sum of
the bytes is D8h, resulting in a 2’s complement of 28h. The low byte, 00h,
provides a pad to the word boundary.
For example, a Reset Configuration Block header
of A104h indicates a non-sequential EEPROM pro-
grammed with a Reset Configuration Block con-
taining 4 bytes of configuration data. This Reset
Configuration Block occupies 6 bytes (3 words) of
EEPROM space (2 bytes for the header and 4 bytes
of configuration data).
3.4.4 Groups of Configuration Data
Configuration data are arranged as groups of
words. Each group contains one or more words of
data that are to be loaded into PacketPage registers.
Crystal LAN™ ISA Ethernet Controller
Description
CS8900A
DS271PP3