PM6344 datasheet(225/256 Pages) PMC

225 / 256 page

STANDARD PRODUCT

PMC-Sierra, Inc.

PM6344 EQUAD

PMC-951013

ISSUE 5

QUADRUPLE E1 FRAMER

212

count becomes non-linear above a 10-4 BER. This must be taken into account

when using CRC-4 counts to determine the BER. Since FEBEs are indications of

CRCEs at the far end, and are accumulated identically to CRCEs, the same

explanation holds for the FEBE event counter.

Figure 34

- CRCE Count vs. BER

1000

200

400

600

800

1200

Average Count Over

Many 1 Second Intervals

CRC Error Event Count Per Second

13.7 Reset Procedure

In the SIGX block that there is a small state machine which will not clear itself out

if it happens to get in an all-ones state. The result is that the SIGX remains

frozen after a reset. The probability that this state will occur is very small, about

1 in 3600 or about 0.028 percent probability of occurrence. If the SIGX function

is not being used, then this condition is a don't care.

To prevent this state from occurring hold the BRCLK and the BTCLK[4:1] signals

low for at least 65ns (greater than one cycle of an 8x clock) after a hardware or

software reset. If ELSTBYP is to be set, do not do so within 65ns of a hardware

or software reset.

For designs where it is not possible to implement the above hardware solution,

the software solution is to perform a self-test after every reset. This self-test

routine would use the TPSC functional block to source known signaling data,

which would be looped back to the SIGX. If the SIGX can detect changes in the

signaling data, then the SIGX block is okay; if it cannot detect changes in the

signaling data, then a reset must be performed and the self-test repeated (until

the SIGX is okay).

PM6344 Datasheet(PDF) 225 Page - PMC-Sierra, Inc