Ethernet Media Access Controller (EMAC)/ Management Data Input/Output (MDIO) Module User's Guide

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5.50.21 Transmit Multiple Collision Frames Register (TXMULTICOLL)
5.50.22 Transmit Excessive Collision Frames Register (TXEXCESSIVECOLL)
5.50.23 Transmit Late Collision Frames Register (TXLATECOLL)
5.50.24 Transmit Underrun Error Register (TXUNDERRUN)
5.50.25 Transmit Carrier Sense Errors Register (TXCARRIERSENSE)
Ethernet Media Access Controller (EMAC) Registers
CRC errors have no effect on this statistic.
The total number of frames transmitted on the EMAC that experienced multiple collisions. Such a frame
is defined as having all of the following:
• Was any data or MAC control frame destined for any unicast, broadcast, or multicast address
• Was any size
• Had no carrier loss and no underrun
• Experienced 2 to 15 collisions before being successfully transmitted. None of the collisions were
late.
CRC errors have no effect on this statistic.
The total number of frames when transmission was abandoned due to excessive collisions. Such a
frame is defined as having all of the following:
• Was any data or MAC control frame destined for any unicast, broadcast, or multicast address
• Was any size
• Had no carrier loss and no underrun
• Experienced 16 collisions before abandoning all attempts at transmitting the frame. None of the
collisions were late.
CRC errors have no effect on this statistic.
The total number of frames when transmission was abandoned due to a late collision. Such a frame is
defined as having all of the following:
• Was any data or MAC control frame destined for any unicast, broadcast, or multicast address
• Was any size
• Had no carrier loss and no underrun
• Experienced a collision later than 512 bit-times into the transmission. There may have been up to 15
previous (non-late) collisions that had previously required the transmission to be reattempted. The
late collisions statistic dominates over the single, multiple, and excessive collisions statistics. If a
late collision occurs, the frame is not counted in any of these other three statistics.
CRC errors, carrier loss, and underrun have no effect on this statistic.
The number of frames sent by the EMAC that experienced FIFO underrun. Late collisions, CRC errors,
carrier loss, and underrun have no effect on this statistic.
The total number of frames on the EMAC that experienced carrier loss. Such a frame is defined as
having all of the following:
• Was any data or MAC control frame destined for any unicast, broadcast, or multicast address
• Was any size
• The carrier sense condition was lost or never asserted when transmitting the frame (the frame is not
retransmitted)
CRC errors and underrun have no effect on this statistic.
SPRUEQ6 – December 2007 Ethernet Media Access Controller (EMAC)/Management Data Input/Output (MDIO) 129
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