Datasheet

DS21Q59 Quad E1 Transceiver

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Transmit and receive CMI is enabled through OUTAC.7. When this register bit is set, the TTIP pin outputs CMI-

coded data at normal TTL-type levels. This signal can be used to directly drive an optical interface. When CMI is

enabled, the user can also use HDB3 coding.

When this register bit is set, the RTIP pin becomes a unipolar CMI input. The CMI signal is processed to extract

and align the clock with data. The bipolar code-violation counter counts CVs in the CMI signal. CVs are defined as

consecutive 1s of the same polarity, as shown in Figure 22-2

. If HDB3 precoding is enabled, the CVs generated by

HDB3 are not counted as errors.

Figure 22-2. Example of CMI Code Violation

0 1 1 1 0 0 1

CLOCK

DAT

CMI

CODE VIOLATION