KSZ8841-16 Micrel Semiconductor, KSZ8841-16 Datasheet - Page 33

• Manufacturer Part Number: KSZ8841-16
• Description: Single-port Ethernet Mac Controller With Non-pci Interface
• Manufacturer: Micrel Semiconductor

The
The data area contains six bytes of Destination Address (DA) followed by six bytes of Source Address (SA), followed by a
variable-length number of bytes. On transmit, all bytes are provided by the CPU, including the source address. The
KSZ8841M does not insert its own SA. The 802.3 Frame Length word (Frame Type in Ethernet) is not interpreted by the
KSZ8841M. It is treated transparently as data both for transmit operations.
Receive Queue (RXQ) Frame Format
The frame format for the receive queue is shown in Table 6. The first word contains the status information for the frame
received. The second word is the total number of bytes of the RX frame. Following that is the packet data area. The
packet data area holds the frame itself. It may or may not include the CRC checksum depending on whether hardware
CRC stripping is enabled.
For receive, the packet receive status always reflects the receive status of the packet received in the current RX packet
memory (see Table 7). The RXSR register indicates the status of the current received frame.
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tra smit Byte Count specifies the total number of bytes to be transmitted from the TXQ. Its format is given in Tab
n
Bit
15-11
10-0
Bit
15
14-8
7
6
5
4
3
Description
Reserved.
TXBC Transmit Byte Count
Transmit Byte Count. Hardware uses the byte count information to conserve the TX buffer
memory for better utilization of the packet memory.
Note: The hardware behavior is unknown if an incorrect byte count information is written to
this field.
Description
RXFV Receive Frame Valid
When set, this field indicates that the present frame in the receive packet memory is valid.
The status information currently in this location is also valid.
When clear, it indicates that there is either no pending receive frame or that the current
frame is still in the process of receiving.
Reserved.
R
W
R
W
a
R
W
Reserved.
RXFT Receive Frame Type
When set, it indicates that the frame is an Ethernet-type frame (frame length is greater than
ddress).
XBF Receive Broadcast Frame
XMF Receive Multicast F
XUF Receive Unicast Frame
hen set, it indicates that this frame has a broadcast address.
hen set, it i
hen set, it indicates that this frame has a u
Writing a 0 value to this field is not permitted.
Packet Memory
Address Offset
0
2
4 - up
ndicates that this frame has a multicast address (including the broadcast
Table 6. Fra
Table 5. Transmit Byte Count Format
rame
me Format for Receiv
Bit 15
2
Status Word
Byte Count
Receive Packet Data
(maximum size is 1916)
nd
33
Byte
nicast address.
e Queue
1
st
Byte
Bit 0
KSZ8841-16/32 MQL/MVL
Rev 1.3
le 5.