LAN9118MT Standard Microsystems (SMSC), LAN9118MT Datasheet - Page 95

• Manufacturer Part Number: LAN9118MT
• Manufacturer: Standard Microsystems (SMSC)

High-Performance Single-Chip 10/100 Non-PCI Ethernet Controller
Datasheet
SMSC LAN9118
6.3.9
31-22
16-19
15-14
BITS
21
20
DESCRIPTION
Reserved
Transmit Threshold Mode (TTM). This bit is used to control the transmit
threshold the MIL uses as shown in the two tables in the TR field of this
register. This bit is ignored when the SF bit is set (1).
This bit should be set to '1' when operating in 10Mbps mode, and cleared
to '0' when operating in 100Mbps mode if the SF bit cleared.
Store and Forward (SF). When set, this bit instructs the MIL to store a
frame of transmit data in the MIL buffer before forwarding to its final
destination.
If this bit is set, the MIL buffers the entire frame before transmitting. TTM
and TR (see bits 21,13, and 12) are treated as Don’t Cares once the SF
mode is selected.
If this bit is reset, the MAC initiates transmission before it receives the entire
frame from the HBI (Host Bus Interface). TTM and TR (see bit 21,13, and
12) determine when the MIL initiates the transmission. If the host cannot
keep up with the MAC transmitting the Ethernet Packet, there is a risk of an
Underrun Error.
TX FIFO Size (TX_FIF_SZ). Sets the size of the TX FIFOs in 1KB values
to a maximum of 14KB. The TX Status FIFO consumes 512 bytes of the
space allocated by TX_FIF_SIZ, and the TX data FIFO consumes the
remaining space specified by TX_FIF_SZ. The minimum size of the TX
FIFOs is 2KB (TX data and status combined). The TX data FIFO is used for
both TX data and TX commands.
The RX status and data FIFOs consume the remaining space, which is
equal to 16KB – TX_FIF_SIZ. See section
Configurable FIFO Memory Allocationon page 97
Reserved
HW_CFG—Hardware Configuration Register
This register controls the hardware configuration of the LAN9118 Ethernet Controller
Offset:
74h
DATASHEET
6.3.9.1 Allowable settings for
95
for more information.
Size:
32 bits
TYPE
R/W
R/W
R/W
RO
RO
Revision 1.0 (03-17-05)
DEFAULT
5h
0
0
-
-