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EMAC Module Registers
5.50.20 Transmit Single Collision Frames Register (TXSINGLECOLL)
The total number of frames transmitted on the EMAC that experienced exactly one 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 one collision before successful transmission. The collision was not late.
CRC errors have no effect on this statistic.
5.50.21 Transmit Multiple Collision Frames Register (TXMULTICOLL)
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.
5.50.22 Transmit Excessive Collision Frames Register (TXEXCESSIVECOLL)
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.
5.50.23 Transmit Late Collision Frames Register (TXLATECOLL)
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.
5.50.24 Transmit Underrun Error Register (TXUNDERRUN)
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.
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SPRUFL5B–April 2011 EMAC/MDIO Module
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