Highly Efficient Single-Chip 10/100 Non-PCI Ethernet Controller
Datasheet
3.9.1
MAC Address Auto-Load
On power-up, hard reset or soft reset, the EEPROM controller attempts to read the first byte of data
from the EEPROM (address 00h). If the value A5h is read from the first address, then the EEPROM
controller will assume that an external Serial EEPROM is present. The EEPROM controller will then
access the next EEPROM byte and send it to the MAC Address register byte 0 (ADDRL[7:0]). This
process will be repeated for the next five bytes of the MAC Address, thus fully programming the 48-
bit MAC address. Once all six bytes have been programmed, the “MAC Address Loaded” bit is set in
the E2P_CMD register. A detailed explanation of the EEPROM byte ordering with respect to the MAC
address is given in Section 5.4.3, "ADDRL—MAC Address Low Register," on page 95.
If an 0xA5h is not read from the first address, the EEPROM controller will end initialization. It is then
the responsibility of the host LAN driver software to set the IEEE address by writing to the MAC’s
ADDRH and ADDRL registers.
The host can initiate a reload of the MAC address from the EEPROM by issuing the RELOAD
command via the E2P command (E2P_CMD) register. If the first byte read from the EEPROM is not
A5h, it is assumed that the EEPROM is not present, or not programmed, and the MAC address reload
will fail. The “MAC Address Loaded” bit indicates a successful reload of the MAC address.
3.9.2
EEPROM Host Operations
After the EEPROM controller has finished reading (or attempting to read) the MAC after power-on, hard
reset or soft reset, the host is free to perform other EEPROM operations. EEPROM operations are
performed using the E2P_CMD and E2P data (E2P_DATA) registers. Section 5.3.23, "E2P_CMD –
EEPROM Command Register," on page 89 provides an explanation of the supported EEPROM
operations.
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 LAN9116
will timeout, and the EPC timeout bit (EPC_TO) in the E2P_CMD register will be set.
Figure 3.3, "EEPROM Access Flow Diagram" illustrates the host accesses required to perform an
EEPROM Read or Write operation.
SMSC LAN9116
Revision 1.1 (05-17-05)
DATA3S1HEET
SMSC [ SMSC CORPORATION ]
