High Performance Two Port 10/100 Managed Ethernet Switch with 32-Bit Non-PCI CPU Interface
Datasheet
10.2.3
Microwire EEPROM
Based on the configuration strap eeprom_type_strap, various sized Microwire EEPROMs are
supported. The varying size ranges are supported by additional bits in the address field
(EPC_ADDRESS) of the EEPROM Command Register (E2P_CMD). Within each size range, the
largest EEPROM uses all the address bits, while the smaller EEPROMs treat the upper address bits
as don’t cares. The EEPROM controller drives all the address bits as requested regardless of the
actual size of the EEPROM. The supported size ranges for Microwire operation are shown in
Table 10.3.
Table 10.3 Microwire EEPROM Size Ranges
eeprom_size_strap[1:0]
# OF ADDRESS BITS
EEPROM SIZE
EEPROM TYPES
00
01
10
11
7
9
128 x 8
93xx46A
256 x 8 and 512 x 8
1024 x 8 and 2048 x 8
RESERVED
93xx56A, 93xx66A
93xx76A, 93xx86A
11
Refer to Section 15.5.10, "Microwire Timing," on page 453 for detailed Microwire timing information.
10.2.3.1
Microwire Master Commands
Table 10.4, Table 10.5, and Table 10.6 detail the Microwire command set, including the number of clock
cycles required, for 7, 9, and 11 address bits respectively. These commands are detailed in the
following sections as well as in Section 14.2.4.1, "EEPROM Command Register (E2P_CMD)," on
page 197.
Table 10.4 Microwire Command Set for 7 Address Bits
START
BIT
DATA TO
EEPROM
DATA FROM
EEPROM
# OF
CLOCKS
INST
OPCODE
ADDRESS
ERASE
ERAL
1
1
1
1
1
1
1
11
00
00
00
10
01
00
A6 A5 A4 A3 A2 A1 A0
-
(RDY/~BSY)
(RDY/~BSY)
Hi-Z
10
10
10
10
18
18
18
1
0
1
0
0
1
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
-
EWDS
EWEN
READ
WRITE
WRAL
-
-
Hi-Z
A6 A5 A4 A3 A2 A1 A0
A6 A5 A4 A3 A2 A1 A0
-
D7 - D0
D7 - D0
D7 - D0
(RDY/~BSY)
(RDY/~BSY)
0
1 X X X X X
Table 10.5 Microwire Command Set for 9 Address Bits
DATA TO
START
BIT
DATA FROM
EEPROM
# OF
CLOCKS
INST
OPCODE
ADDRESS
EEPROM
ERASE
ERAL
1
1
11
00
A8 A7 A6 A5 A4 A3 A2 A1 A0
-
-
(RDY/~BSY)
(RDY/~BSY)
12
12
1
0
X
X
X
X
X X X
Revision 1.2 (04-08-08)
144
SMSC LAN9312
DATASHEET
SMSC [ SMSC CORPORATION ]
