CS89712 View Datasheet(PDF) - Cirrus Logic
Part Name
Description
MFG CO.
'CS89712' PDF : 170 Pages View PDF
CS89712
Section 2.32, “Basic Receive Operation” and Sec-
tion 2.32.7, “Receive Ethernet Port Locations”
provide a detailed description of packet reception.
2.24 Programming the EEPROM
After initialization, software can access the EE-
PROM through the Ethernet port by writing one of
seven commands to the EEPROM Command regis-
ter. Figure 12 shows the format of the EEPROM
Command register.
2.24.1 EEPROM Commands
The seven commands used to access the EEPROM
are: Read, Write, Erase, Erase/Write Enable,
Erase/Write Disable, Erase-All, and Write-All.
They are described in Table 26.
2.24.2 EEPROM Command Execution
During the execution of a command, the two Op-
code bits, followed by the six bits of address (for a
’C46 or ’CS46) or eight bits of address (for a ’C56,
’CS56, ’C66 or ’CS66), are shifted out of the Ether-
net port, into the EEPROM. If the command is a
Write, the data in the EEPROM Data register
(Ethernet Port offset address 0042h) follows. If the
command is a Read, the data in the specified EE-
PROM location is written into the EEPROM Data
register. If the command is an Erase or Erase-All,
no data is transferred to or from the EEPROM Data
register. Before issuing any command, the SI-
BUSY bit (Register 16, SelfST, bit 8) must clear.
After each command has been issued, software
must wait again for SIBUSY to clear.
2.24.3 Enabling Access to the EEPROM
The Erase/Write Enable command provides protec-
tion from accidental writes to the EEPROM. The
software must write an Erase/Write Enable com-
mand before it attempts to write to or erase any EE-
PROM memory location. Once the software has
finished altering the contents of the EEPROM, it
must write an Erase/Write Disable command to
prevent unwanted modification of the EEPROM.
AD7 - AD0 used with ’C56,
’CS56, ’C66 and ’CS66
F EDCB A
9876543210
X X X X X ELSEL OP1 OP0 AD7 AD6 AD5 AD4 AD3 AD2 AD1 AD0
AD5 - AD0 used with
’C46 and ’CS46
Bit
[F:B]
[A]
[9:8]
[7:0]
Name
ELSEL
OP1, OP0
AD7 to AD0
Description
Reserved
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.
Opcode: Indicates what command is being executed (see next section).
EEPROM Address: Address of EEPROM word being accessed.
Figure 12. EEPROM Command Register Format
DS502PP2
45
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