www.ti.com
Ethernet Subsystem Registers
14.5.7.6 BOFFTEST Register (offset = 14h) [reset = 0h]
BOFFTEST is shown in Figure 14-178 and described in Table 14-194.
CPGMAC_SL BACKOFF TEST REGISTER
Figure 14-178. BOFFTEST Register
31 30 29 28 27 26 25 24
Reserved PACEVAL RNDNUM
R-0h R/W-0h R/W-0h
23 22 21 20 19 18 17 16
RNDNUM
R/W-0h
15 14 13 12 11 10 9 8
COLL_COUNT Reserved TX_BACKOFF
R-0h R-0h R-0h
7 6 5 4 3 2 1 0
TX_BACKOFF
R-0h
LEGEND: R/W = Read/Write; R = Read only; W1toCl = Write 1 to clear bit; -n = value after reset
Table 14-194. BOFFTEST Register Field Descriptions
Bit Field Type Reset Description
31 Reserved R 0h
30-26 PACEVAL R/W 0h Pacing Register Current Value.
A non-zero value in this field indicates that transmit pacing is active.
A transmit frame collision or deferral causes paceval to loaded with
decimal 31, good frame transmissions (with no collisions or
deferrals) cause paceval to be decremented down to zero.
When paceval is nonzero, the transmitter delays 4 IPGs between
new frame transmissions after each successfully transmitted frame
that had no deferrals or collisions.
Transmit pacing helps reduce "capture" effects improving overall
network bandwidth.
25-16 RNDNUM R/W 0h Backoff Random Number Generator - This field allows the Backoff
Random Number Generator to be read (or written in test mode only).
This field can be written only when mtest has previously been set.
Reading this field returns the generator's current value.
The value is reset to zero and begins counting on the clock after the
deassertion of reset.
15-12 COLL_COUNT R 0h
Collision Count - The number of collisions the current frame has
experienced.
11-10 Reserved R 0h
9-0 TX_BACKOFF R 0h Backoff Count - This field allows the current value of the backoff
counter to be observed for test purposes.
This field is loaded automatically according to the backoff algorithm,
and is decremented by one for each slot time after the collision.
1419
SPRUH73H–October 2011–Revised April 2013 Ethernet Subsystem
Submit Documentation Feedback
Copyright © 2011–2013, Texas Instruments Incorporated
To Next Page
Loading...
Need help?
General
