
Micrel, Inc.
KSZ8851-16MLLJ
March 2010
55
M9999-030210-1.0
Transmit Control Register (0x70 – 0x71): TXCR
This register holds control information programmed by the CPU to control the QMU transmit module function.
Bit
Default Value
R/W
Description
15-9
-
RO
Reserved.
8
0x0
RW
TCGICMP Transmit Checksum Generation for ICMP
When this bit is set, The KSZ8851-16MLLJ is enabled to transmit ICMP frame (only for
non-fragment frame) checksum generation.
7
0x0
RO
Reserved.
6
0x0
RW
TCGTCP Transmit Checksum Generation for TCP
When this bit is set, The KSZ8851-16MLLJ is enabled to transmit TCP frame
checksum generation.
5
0x0
RW
TCGIP Transmit Checksum Generation for IP
When this bit is set, The KSZ8851-16MLLJ is enabled to transmit IP header checksum
generation.
4
0x0
RW
FTXQ Flush Transmit Queue
When this bit is set, The transmit queue memory is cleared and TX frame pointer is
reset.
Note: Disable the TXE transmit enable bit[0] first before set this bit, then clear this bit
to normal operation.
3
0x0
RW
TXFCE Transmit Flow Control Enable
When this bit is set and the KSZ8851-16MLLJ is in full-duplex mode, flow control is
enabled. The KSZ8851-16MLLJ transmits a PAUSE frame when the Receive Buffer
capacity reaches a threshold level that will cause the buffer to overflow.
When this bit is set and the KSZ8851-16MLLJ is in half-duplex mode, back-pressure
flow control is enabled. When this bit is cleared, no transmit flow control is enabled.
2
0x0
RW
TXPE Transmit Padding Enable
When this bit is set, the KSZ8851-16MLLJ automatically adds a padding field to a
packet shorter than 64 bytes.
Note: Setting this bit requires enabling the add CRC feature (bit1=1) to avoid CRC
errors for the transmit packet.
1
0x0
RW
TXCE Transmit CRC Enable
When this bit is set, the KSZ8851-16MLLJ automatically adds a 32-bit CRC checksum
field to the end of a transmit frame.
0
0x0
RW
TXE Transmit Enable
When this bit is set, the transmit module is enabled and placed in a running state.
When reset, the transmit process is placed in the stopped state after the transmission
of the current frame is completed.