Cirrus Logic CS8900A - Manual (Page 25)

DS271F5 25
CS8900A
Crystal LAN™ Ethernet Controller
CIRRUS LOGIC PRODUCT DATASHEET
initialization is complete (configuration loaded
from EEPROM or reset to default configura-
tion) the INITD bit is set (Register 16, SelfST,
bit 7).
3.5 Programming the EEPROM
After initialization, the host can access the EE-
PROM through the CS8900A by writing one of
seven commands to the EEPROM Command
register (PacketPage base + 0040h). Figure 5
shows the format of the EEPROM Command
register.
3.5.1 EEPROM Commands
The seven commands used to access the EE-
PROM are: Read, Write, Erase, Erase/Write
Enable, Erase/Write Disable, Erase-All, and
Write-All. They are described in Table 8.
3.5.2 EEPROM Command Execution
During the execution of a command, the two
Opcode bits, followed by the six bits of address
(for a ’C46 or ’CS46) or eight bits of address
F
X
E
X
D
X
C
X
B
X ELSEL OP1 OP0
A 9 8
AD5 AD4
5 4 7 6
AD7 AD6
1 0 3 2
AD1 AD0 AD3 AD2
AD5 - AD0 used with
'C46 and 'CS46
AD7 - AD0 used with 'C56,
'CS56, 'C66 and 'CS66
Figure 5. EEPROM Command Register Format
Bit Name Description
[F:B] Reserved
[A] ELSEL External Logic Select: When clear, the EECS pin is used to select the EEPROM.
When set, the ELCS pin is used to select the external LA decode circuit.
[9:8] OP1, OP0 Opcode: Indicates what command is being executed (see next section).
[7:0] AD7 to AD0 EEPROM Address: Address of EEPROM word being accessed.
Command Opcode
(bits 9,8)
EEPROM Address
(bits 7 to 0)
Data EEPROM Type Execution
Time
Read Register 1,0 word address yes all 25 µs
Write Register 0,1 word address yes all 10 ms
Erase Register 1.1 word address no all 10 ms
Erase/Write Enable 0,0 XX11-XXXX no ‘CS46, ‘C46 9 µs
11XX-XXXX no ‘CS56, ‘C56, ‘CS66, ‘C66 9 µs
Erase/Write Disable 0,0
0,0 XX00-XXXX no ‘CS46, ‘C46 9 µs
00XX-XXXX no ‘CS56, ‘C56, ‘CS66, ‘C66 9 µs
Erase-All Registers 0,0
0,0 XX10-XXXX no ‘CS46, ‘C46 10 ms
10XX-XXXX no ‘CS56, ‘C56, ‘CS66, ‘C66 9 µs
Write-All Register 0,0
0,0 XX01-XXXX yes ‘CS46, ‘C46 10 ms
01XX-XXXX yes ‘CS56, ‘C56, ‘CS66, ‘C66 10 ms
Table 8. EEPROM Commands