LAN9353 Datasheet, PDF (205/523 Pages) Microchip Technology – Interfaces at up to 200Mbps via Turbo MII

LAN9353
Packet padding and cyclic redundant code (FCS) calculation may be optionally performed by the transmit MAC. The
auto-padding process automatically adds enough zeros to packets shorter than 64 bytes. The auto-padding and FCS
generation is controlled via the TX Pad Enable bit of the Port x MAC Transmit Configuration Register (MAC_TX_CF-
G_x).
When in full-duplex mode, the transmit MAC uses the flow-control algorithm specified in IEEE 802.3. MAC pause frames
are used primarily for flow control packets, which pass signaling information between stations. MAC pause frames have
a unique type of 8808h and a pause op-code of 0001h. The MAC pause frame contains the pause value in the data field.
The flow control manager will auto-adapt the procedure based on traffic volume and speed to avoid packet loss and
unnecessary pause periods.
When in half-duplex mode, the MAC uses a back pressure algorithm. The back pressure algorithm is based on a forced
collision and an aggressive back-off algorithm.
For information on MAC EEE functionality, refer to Section 10.2.3, "IEEE 802.3az Energy Efficient Ethernet," on
page 205.
10.2.2.1 Transmit Counters
The transmit MAC gathers statistics on each packet and increments the related counter registers. The following transmit
counters are supported for each Switch Fabric port. Refer to Table 10-9, “Indirectly Accessible Switch Control and Status
Registers,” on page 246 and Section 10.7.2.29 through Section 10.7.2.46 for detailed descriptions of these counters.
• Total packets deferred (Section 10.7.2.29, on page 276)
• Total pause packets (Section 10.7.2.30, on page 276)
• Total OK packets (Section 10.7.2.31, on page 277)
• Total packets 64 bytes in size (Section 10.7.2.32, on page 277)
• Total packets 65 through 127 bytes in size (Section 10.7.2.33, on page 278)
• Total packets 128 through 255 bytes in size (Section 10.7.2.34, on page 278)
• Total packets 256 through 511 bytes in size (Section 10.7.2.35, on page 279)
• Total packets 512 through 1023 bytes in size (Section 10.7.2.36, on page 279)
• Total packets 1024 through maximum bytes in size (Section 10.7.2.37, on page 280)
• Total undersized packets (Section 10.7.2.38, on page 280)
• Total bytes transmitted from all packets (Section 10.7.2.39, on page 281)
• Total broadcast packets (Section 10.7.2.40, on page 281)
• Total multicast packets (Section 10.7.2.41, on page 282)
• Total packets with a late collision (Section 10.7.2.42, on page 282)
• Total packets with excessive collisions (Section 10.7.2.43, on page 282)
• Total packets with a single collision (Section 10.7.2.44, on page 283)
• Total packets with multiple collisions (Section 10.7.2.45, on page 283)
• Total collision count (Section 10.7.2.46, on page 283)
• Total number of TX LPIs Generated (Section 10.7.2.47, on page 284)
• Total time in TX LPI state (Section 10.7.2.48, on page 284)
10.2.3 IEEE 802.3AZ ENERGY EFFICIENT ETHERNET
The device supports Energy Efficient Ethernet (EEE) in 100 Mbps mode as defined in the most recent version of the
IEEE 802.3az standard.
10.2.3.1 TX LPI Generation
The process of when the MAC should indicate LPI requests to the PHY is divided into two sections:
• CLIENT LPI REQUESTS TO MAC
• MAC LPI REQUEST TO PHY
 2015 Microchip Technology Inc.
DS00001925A-page 205