CS8900A
Crystal LAN™ Ethernet Controller
3.4 Configurations with EEPROM
3.4.1 EEPROM Interface
PacketPage Register
Register Descriptions
I/O Base Address*
Address
Contents
The interface to the EEPROM consists of the
four signals shown in Table 6.
0020h
0300h
0022h
XXXX XXXX Interrupt Number
XXXX X100
CS8900A Pin
(Pin #)
EEPROM
Pin
CS8900A Function
0024h
0026h
XXXX XXXX DMA Channel
XXXX XX11
EECS (Pin 3) EEPROM Chip Select Chip Select
EESK (PIN 4) 1 MHz EEPROM
Serial Clock output
Clock
Data In
Data Out
0000h
DMA Start of Frame
Offset
EEDO (Pin 5) EEPROM Data Out
(data to EEPROM)
0028h
002Ah
002Ch
0030h
X000h
0000h
DMA Frame Count
DMA Byte Count
EEDI (Pin 6) EEPROM Data in
(data from EEPROM)
XXX0 0000h Memory Base Address
XXX0 0000h Boot PROM Base
Address
Table 6. EEPROM Interface
3.4.2 EEPROM Memory Organization
0034h
XXX0 0000h Boot PROM Address
Mask
If an EEPROM is used to store initial configu-
ration information for the CS8900A, the EE-
PROM is organized in one or more blocks of
16-bit words. The first block in EEPROM, re-
ferred to as the Configuration Block, is used to
configure the CS8900A after reset. An exam-
ple of a typical Configuration Block is shown in
Table 7. Additional blocks containing user data
may be stored in the EEPROM. However, the
Configuration Block must always start at ad-
dress 00h and be stored in contiguous memo-
ry locations.
0102h
0104h
0106h
0108h
010Ah
010Ch
010Eh
0110h
0112h
0114h
0116h
0118h
0003h
Register 3 - RxCFG
Register 5 - RxCTL
Register 7 - TxCFG
Register 9 - TxCMD
Register B - BufCFG
Reserved
0005h
0007h
0009h
000Bh
Undefined
Undefined
Undefined
00013h
0015h
Reserved
Reserved
Register 13 - LineCTL
Register 15 - SelfCTL
Register 17 - BusCTL
Register 19 - TestCTL
0017h
3.4.3 Reset Configuration Block
0019h
* I/O base address is unaffected by Software Suspend mode.
The first block in EEPROM, referred to as the
Reset Configuration Block, is used to automat-
ically program the CS8900A with an initial con-
figuration after a reset. Additional user data
may also be stored in the EEPROM if space is
available. The additional data are stored as
16-bit words and can occupy any EEPROM
address space beginning immediately after
the end of the Reset Configuration Block up to
address 7Fh, depending on EEPROM size.
This additional data can only be accessed
through software control (refer to Section 3.5
on page 25 for more information on accessing
Table 4. Default Configuration
EEPROM Type
‘C46 (non-sequential)
‘CS46 (sequential)
‘C56 (non-sequential)
‘CS56 (sequential)
‘C66 (non-sequential)
‘CS66 (sequential)
Size (16-bit words)
64
64
128
128
256
256
Table 5. Supported EEPROM Types
CIRRUS LOGIC PRODUCT DATASHEET
DS271F4
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