Dead Band
Dead band and phase overlap checks are
based on specific edges hence whether specific edges as configured in SIGPOL or ones
opposite to the SIG or both to be compared is critical to the configuration.
Note: EDGESPAN configuration is not used for dead-band check as
edges of two signals of the configured type are compared on continuous basis for any
violation on the minimum width. Check starts after trigger to search for configured
edge type for each signal.
This configuration of singular or both
edges of dead band check is done in SIGTOSIGCFG[SIGTOSIG_DBCMPEN]. The order of
edges can be either SIG1 or SIG2, rise or fall but only edges which are configured
need to be measured. Dead band looks only for distance between edges if less than
compare value defined in SIGTOSIG_DBOLAPA/B[DBCMPA/B].
- When
SIGTOSIGCFG[SIGTOSIG_DBCMPEN] bit is enabled and SIGTOSIGCFG[DBCMPTYPE] = 0x0,
this configuration compares the distance between configured edges of the
respective signal. For example, if SIG1-rise and SIG2-fall is to be compared,
then after trigger on SIG1-rise occurs then distance to SIG2-fall can be
compared to the compare value.
- When SIGTOSIGCFG[DBCMPTYPE] = 0x1
with SIGTOSIGCFG[SIGTOSIG_DBCMPEN] enabled, this configuration allows either
comparing configured or the compared and complementary edges for dead-band.
Complementary check can be specifically enabled. For example, if configured
edges are SIG1-fall and SIG2-rise, then upon enabling both SIG1-fall to
SIG2-rise and SIG1-rise to SIG2-fall is checked.
- The edge to edge distance is
measured as per configuration continuously edge after edge. If SIG1 edge of
programmed type (for example, Rise) is received then counter starts counting
till SIG2 edge of configured type (for example, Fall) occurs.
Note: For the dead-band check the EDGE_SPAN configuration is
ignored and the comparison is performed for every two associated or associated +
complementary edges.
- Same is applicable if the order
of signals reverses and SIG2 (for example, Fall) occurs ahead of SIG1 (for
example, Rise).
- In case dead-band check is
enabled for either edge (DBAND_CHK_TYPE=0x1) then upon detecting edge on either
signal say SIG1 (for example, Rise) in this case, corresponding configured edge
on SIG2 (for example, Fall) is detected and the interim period is checked for
meeting at least required threshold compare.
- Further for case in 2. The
opposite edge of either signal configured in EDGE_TYPE (for example, SIG2.Rise)
is detected and the distance to corresponding opposite edge of other signal (for
example, SIG1.Fall) is validated. Thus both edges of signals are validated
against the corresponding edges of paired signal.
- In case after detection of
specific edge (for example, SIG1.Rise), if corresponding edge (for example,
SIG2.Fall) for paired signal does not occur before the opposite edge (for
example, SIG1.Fall) of the same signal then the count is reset and check is
started for the recent edge.
Phase Overlap
Phase measurement also takes settings
similar to dead-band, except that the level after configured edge is measured for
overlap. Order of signal occurrence is not concern as overlap is measured.
- Signal to Signal phase overlap :
Checks particular signal levels (say SIG1-high and SIG2-low) are simultaneously
asserted with time overlap within range of minimum to maximum. Measurement
starts when both signals at configured level. Whereas upon exit of either signal
from the level sought, the measurement is stopped and compared against
SIGTOSIG_DBOLAPA/B[DBCMPA/B] with margin of +/- OLAPCMPA/BMARGIN
- In this mode of operation,
expected the waveforms provided for comparison do not have individual pulse
widths such as one signal has pulse more than 2˟ wider than other. If for some
reason while one of the signals remains asserted and the second signal gets
reasserted, then a second time the measurement is triggered flushing the
previous measurement. However, if there are errors raised in earlier comparisons
then those are not deasserted until cleared by software.
- SIGTOSIGCFG[OLAPCMPTYPE]: Enables
and selects the type of overlap comparison. The following table indicates the
configuration and the effect on the checks. The example is for the configuration
of rise edge of the SIG1 and Fall edge of the SIG2.
- For the phase-overlap check the
EDGESPAN configuration is ignored and the comparison is performed for every two
configured or configured complementary edges.
| Control |
Value |
Check |
Check for Example |
| OLAPCMPTYPE |
0x0 |
0x0 - Overlap of levels per configuration (edge configuration
extended to derive level). |
Overlap of SIG1-level-High and SIG2-level-Low |
| OLAPCMPTYPE |
0x1 |
0x1 - Overlap of levels per configuration and complementary
levels as well. |
Overlap of
SIG1-level-High and SIG2-level-Low and
Overlap of
SIG1-level-Low and SIG2-level-High
|