High-Performance Single-Chip 10/100 Ethernet Controller with HP Auto-MDIX and Industrial Temperature Support
Datasheet
If the EEPROM operation is the “write location” (WRITE) or “write all” (WRAL) commands, the host
must first write the desired data into the E2P_DATA register. The host must then issue the WRITE or
WRAL command using the E2P_CMD register by setting the EPC_CMD field appropriately. If the
operation is a WRITE, the EPC_ADDR field in E2P_CMD must also be set to the desired location. The
command is executed when the host sets the EPC_BSY bit high. The completion of the operation is
indicated when the EPC_BSY bit is cleared.
If the EEPROM operation is the “read location” (READ) operation, the host must issue the READ
command using the E2P_CMD with the EPC_ADDR set to the desired location. The command is
executed when the host sets the EPC_BSY bit high. The completion of the operation is indicated when
the EPC_BSY bit is cleared, at which time the data from the EEPROM may be read from the
E2P_DATA register.
Other EEPROM operations are performed by writing the appropriate command to the EPC_CMD
register. The command is executed when the host sets the EPC_BSY bit high. The completion of the
operation is indicated when the EPC_BSY bit is cleared. In all cases the host must wait for EPC_BSY
to clear before modifying the E2P_CMD register.
Note: The EEPROM device powers-up in the erase/write disabled state. To modify the contents of
the EEPROM the host must first issue the EWEN command.
If an operation is attempted, and an EEPROM device does not respond within 30mS, the LAN9218i
will timeout, and the EPC timeout bit (EPC_TO) in the E2P_CMD register will be set.
Figure 3.2, "EEPROM Access Flow Diagram" illustrates the host accesses required to perform an
EEPROM Read or Write operation.
EEPROM Write
EEPROM Read
Idle
Idle
Write
Command
Register
Write Data
Register
Write
Read
Command
Command
Register
Register
Busy Bit = 0
Read
Command
Register
Read Data
Register
Busy Bit = 0
Figure 3.2 EEPROM Access Flow Diagram
The host can disable the EEPROM interface through the GPIO_CFG register. When the interface is
disabled, the EEDIO and ECLK signals can be used as general-purpose outputs, or they may be used
to monitor internal MII signals.
SMSC LAN9218i
31
Revision 1.8 (06-06-07)
DATASHEET
SMSC [ SMSC CORPORATION ]
