CS8900A
Crystal LAN™ Ethernet Controller
initialization is complete (configuration loaded
from EEPROM or reset to default configura-
register (PacketPage base + 0040h). Figure 5
shows the format of the EEPROM Command
tion) the INITD bit is set (Register 16, SelfST, register.
bit 7).
3.5.1 EEPROM Commands
3.5 Programming the EEPROM
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.
After initialization, the host can access the EE-
PROM through the CS8900A by writing one of
seven commands to the EEPROM Command
Command
Opcode
(bits 9,8)
EEPROM Address Data
(bits 7 to 0)
EEPROM Type
Execution
Time
Read Register
Write Register
1,0
0,1
1.1
0,0
word address
word address
word address
XX11-XXXX
11XX-XXXX
XX00-XXXX
00XX-XXXX
XX10-XXXX
10XX-XXXX
XX01-XXXX
01XX-XXXX
yes
yes
no
all
25 µs
10 ms
10 ms
9 µs
all
Erase Register
Erase/Write Enable
all
no
‘CS46, ‘C46
no
‘CS56, ‘C56, ‘CS66, ‘C66
‘CS46, ‘C46
9 µs
Erase/Write Disable
Erase-All Registers
Write-All Register
0,0
0,0
no
9 µs
no
‘CS56, ‘C56, ‘CS66, ‘C66
‘CS46, ‘C46
9 µs
0,0
0,0
no
10 ms
9 µs
no
‘CS56, ‘C56, ‘CS66, ‘C66
‘CS46, ‘C46
0,0
0,0
yes
yes
10 ms
10 ms
‘CS56, ‘C56, ‘CS66, ‘C66
Table 8. EEPROM Commands
3.5.2 EEPROM Command Execution
Opcode bits, followed by the six bits of address
(for a ’C46 or ’CS46) or eight bits of address
During the execution of a command, the two
AD 7 - AD0 used w ith 'C 56,
'C S56, 'C 66 and 'C S66
F
X
E
X
D
X
C
X
B
X
A
9
8
7
6
5
4
3
2
1
0
ELSEL OP1 OP0 AD7 AD6 AD5 AD4 AD3 AD2 AD1 AD0
AD5 - AD0 used w ith
'C46 and 'CS46
Bit
[F:B]
[A]
Name
Description
Reserved
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]
[7:0]
OP1, OP0
Opcode: Indicates what command is being executed (see next section).
AD7 to AD0 EEPROM Address: Address of EEPROM word being accessed.
Figure 5. EEPROM Command Register Format
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