Achronix Speedster22i PCIe - Manual (Page 65)

UG030, April 26, 2013 65
Field Name Default Values Description Verilog Parameter
unsure which method they
should use.
Algorithm –
Pre Cursor
Step Size 4 1-16 5.3.3.2 Algorithm Method
Evenly step through the possible
coefficient values. Complete
coefficient range coverage at the
expense of longer run time.
for (pre = 0; pre <=
eq_alg_pre_cursor_limit; pre =
pre +
eq_alg_pre_cursor_step_size)
for (post = 0; post <=
eq_alg_post_cursor_limit; post =
post +
eq_alg_post_cursor_step_size)
try {post, pre}
Note: Post-Cursor values (post)
from 0 to 32 (0 to 0.5) are possible
Note: Pre-Cursor values (pre)
from 0 to 16 (0 to 0.25) are
possible
Stepping through all 17 (0-16)
Pre-Cursor values and all 33 (0-
32) Post-Cursor values takes 561
iterations. Step size is increased to
walk through the values more
quickly (and coarsely). Limits are
lowered to exclude larger values
that are less likely to produce the
desired results.
For example:
Steps of 4 for Pre-Cursor and 8 for
Post Cursor with Limits == 16 and
32 respectively requires 25
iterations.
Steps of 8 for Pre-Cursor and 16
for Post Cursor with Limits == 16
and 32 respectively requires 9
iterations.
Be careful when assigning step
sizes not to exceed the
Equalization time limit.
The Algorithm Method works
best with PHY which take
significantly less than the
maximum of 2mS to evaluate CFG_8G_CONSTANTS_
EQ_ALG_PRE_CURSOR_
STEP_SIZE
Algorithm –
Post Cursor
Step Size 8 1-32 CFG_8G_CONSTANTS_
EQ_ALG_POST_CURSO
R_STEP_SIZE
Algorithm –
Pre Cursor
Limit 16 0-16 CFG_8G_CONSTANTS_
EQ_ALG_PRE_CURSOR_
LIMIT
Algorithm –
Post Cursor
Limit 32 0-32 CFG_8G_CONSTANTS_
EQ_ALG_POST_CURSO
R_LIMIT