7.3.13.2 Forward Channel and Back Channel Error Checking

The deserializer, after locking to the serial stream, compares the recovered serial stream with all-zeroes and records any errors in the status registers. Errors are also dynamically reported on the PASS pin of the deserializer. Forward channel errors may also be read from register 0x25 (Table 11).

The back-channel data is checked for CRC errors once the serializer locks onto the back-channel serial stream, as indicated by the link detect status (register bit 0x0C[0] - Table 11). CRC errors are recorded in an 8-bit register in the serializer. The register is cleared when the serializer enters BIST mode. As soon as the serializer enters BIST mode, the functional mode CRC register starts recording any back channel CRC errors. The BIST mode CRC error register is active in BIST mode only, and keeps the record of the last BIST run until either the error is cleared or the serializer enters BIST mode again.

Figure 27. BIST Waveforms