W89C841F Datasheet, PDF (26/102 Pages) Winbond – 3-IN - 1 10/100M FAST ETHERNET CONTROLLER

W89C841F/D
W89C840F transmit DMA function performs the data transfer from the host memory through on-chip
PCI bus master into the internal 2 Kbytes transmit FIFO. The transmit DMA state machine will request
the MAC to send out the data in the TX FIFO onto the transmission media.
Media Access Control (MAC) Function
The MAC function of W89C841F fully meets the requirements defined by the IEEE802.3u
specification. MAC performs many transmission functions, including the inter-frame spacing function,
collision detection, collision enforcement, collision backoff and retransmission. MAC performs the
receive functions including the address recognition function, the frame check sequence validation, the
frame disassembly, framing and collision filtering.
Full Duplex and Half Duplex Function
In the half duplex mode, the MAC should perform the transmission or reception operation at the
different time frame. Simultaneous transmission and reception is not allowed. However, in the time
duration from 10 bits time to 16 bits time after the packet is transmitted, the active COL signal is
recognized as a SQE test signal but not a collision event. The active signal CRS will be recognized as
a loopback carrier sense signal when the MAC is transmitting a packet. The carrier sense lost status is
relied on the CRS. Normally, there should not be any carrier sense lost during transmitting if the media
and devices are functional. In the full duplex mode, the MAC can perform the transmission and receive
operation at the same time. Collision event, SQE lost and carrier sense lost are not defined in the full
duplex mode. After auto-negotiation completed, network duplex mode can be decided by internal
PHYceiver.
Network Media Speed Function
W89C841F can work at network speed of 100M or 10Mbps. After auto-negotiation completed, network
speed can be decided by internal PHYceiver.
Flow Control in Full Duplex Mode
W89C841F supports asymmetrical and symmetrical flow control in full duplex mode compliant with
IEEE802.3x. After auto-negotiation completed, W89C841F will decide to operate in which flow control
mode (symmetrical, asymmetrical or none).
When the receiving byte counts of RX FIFO is over the high threshold defined at field HTV of register
Ddc/DRFCTV[17:9], a pause frame with MAX pause time (FFFFh) is transmitted to prevent the other
station keeping on transmitting packets to W89C841F. So W89C841F will not drop packets due to RX
FIFO overflow. When the receiving byte count of RX FIFO is below the low threshold defined at field
LTV of register Ddc/DRFCTV[8:0], a pause frame with MIN pause time (0000h) is transmitted to let the
other station starting to transmit packets to W89C841F.
If W89C841F receives a pause packet with non-zero pause time, the packet transmission ability will be
inhibited until the pause time counts down to 0. Pause frame is a flow control packet. It is not a data
packet and will be dropped by W89C841F.
Priority Tagged Frame Supporting QOS
A priority tagged frame defined at IEEE 802.1p contains a VLAN tag which indicates the user priority
and Null VLAN ID (VID = 0). W89C841F can transmit and receive priority tagged frames to improve the
network quality of service if bit VLANEN of register C1c/CNCR is set.
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