LAN9115-MT Standard Microsystems (SMSC), LAN9115-MT Datasheet - Page 82

• Manufacturer Part Number: LAN9115-MT
• Manufacturer: Standard Microsystems (SMSC)

Specifications of LAN9115-MT

• Operating Supply Voltage (typ): 3.3V
• Operating Supply Voltage (min): 2.97V
• Operating Supply Voltage (max): 3.63V
• Operating Temperature Classification: Commercial
• Mounting: Surface Mount
• Pin Count: 100
• Lead Free Status / RoHS Status: Compliant

Revision 1.5 (07-11-08)
5.3.9.1
BITS
3
2
1
0
DESCRIPTION
External PHY Detect (EXT_PHY_DET). This bit reflects the latched value
of the EXT_PHY_DET strap. The EXT_PHY_DET strap is used to indicate
the presence of an external PHY. This strap is latched from the value of the
external MDIO signal upon power-up or hard reset. If MDIO is pulled high a
‘1’ will be seen in this bit. If MDIO is pulled low a ‘0’ will be seen in this bit.
The RXT_PHY_DET strap has no other effect on the internal logic. Its only
function is to give the system designer a mechanism to indicate the
presence of an external PHY to a software application.
External PHY Enable (EXT_PHY_EN). When set to a ‘1’, this bit enables
the external MII port. When cleared, the internal PHY is enabled and the
external MII port is disabled.
Notes:
Soft Reset Timeout (SRST_TO).
internal PHY is not in the operational state (RX_CLK and TX_CLK running), the reset
will not complete and the soft reset operation will timeout and this bit will be set to a
‘1’. The host processor must correct the problem and issue another soft reset.
Soft Reset (SRST). Writing 1 generates a software initiated reset. This reset
generates a full reset of the MAC CSR’s. The SCSR’s (system command
and status registers) are reset except for any NASR bits. Soft reset also
clears any TX or RX errors (TXE/RXE). This bit is self-clearing.
Notes:
This signal does not control multiplexing of the SMI port or the TX_CLK
or RX_CLK signals.
There are restrictions on the use of this bit. Please refer to
"MII Interface - External MII Switching," on page 44
Do not attempt a soft reset unless the internal PHY is fully awake and
operational. After a PHY reset, or when returning from a reduced power
state, the PHY must given adequate time to return to the operational state
before a soft reset can be issued. The internal RX_CLK and TX_CLK
signals must be running for a proper software reset. Please refer to
Section 6.8, "Reset Timing," on page 127
The LAN9115 must always be read at least once after power-up, reset, or
upon return from a power-saving state or write operations will not function.
Allowable settings for Configurable FIFO Memory Allocation
TX and RX FIFO space is configurable through the CSR - HW_CFG register defined above. The user
must select the FIFO allocation by setting the TX FIFO Size (TX_FIF_SZ) field in the hardware
configuration (HW_CFG) register. The TX_FIF_SZ field selects the total allocation for the TX data path,
including the TX Status FIFO size. The TX Status FIFO size is fixed at 512 Bytes (128 TX Status
DWORDs). The TX Status FIFO length is subtracted from the total TX FIFO size with the remainder
being the TX data FIFO Size. Note that TX data FIFO space includes both commands and payload
data.
RX FIFO Size is the remainder of the unallocated FIFO space (16384 bytes – TX FIFO Size). The RX
Status FIFO size is always equal to 1/16 of the RX FIFO Size. The RX Status FIFO length is subtracted
from the total RX FIFO size with the remainder being the RX data FIFO Size.
For example, if TX_FIF_SZ = 6 then:
Total TX FIFO Size = 6144 Bytes (6KB)
TX Status FIFO Size = 512 Bytes (Fixed)
TX Data FIFO Size = 6144 – 512 = 5632 Bytes
If a software reset is attempted when the
DATASHEET
for details on PHY reset timing.
82
Highly Efficient Single-Chip 10/100 Non-PCI Ethernet Controller
for details.
Section 3.12,
TYPE
RW
RO
RO
SC
EXT_PHY_D
SMSC LAN9115
ET strap pin
Dependant
DEFAULT
Datasheet
on
0
0
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