PM5347 datasheet(242/302 Pages) PMC

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PM5347 S/UNI-PLUS

DATA SHEET

PMC-941033

ISSUE 6

SATURN USER NETWORK INTERFACE PLUS

PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA, INC., AND FOR ITS CUSTOMERS’ INTERNAL USE

226

and RSOC) are coincident with Word 1 (containing the first two header octets).

Word 3 of this structure contains the HCS octet in bits 15 to 8.

In the receive direction, the lower 8 bits of Word 3 contain the HCS status octet.

An all-zeros pattern in these 8 bits indicates that the associated header is error

free. An all-ones pattern indicates that the header contains an uncorrectable

error (if the HCSPASS bit in the RACP Control Register is set to logic zero, the

all-ones pattern will never be passed in this structure). An alternating ones and

zeros pattern (0xAA) indicates that the header contained a correctable error. In

this case the header passed through the structure is the "corrected" header.

In the transmit direction, the HCS bit in the TACP Control register determines

whether the HCS is calculated internally or is inserted directly from the upper 8

bits of Word 3. The lower 8 bits of Word 3 contain the HCS control octet. The

HCS control octet is an error mask that allows the insertion of one or more errors

in the HCS octet. A logic one in a given bit position causes the inversion of the

corresponding HCS bit position (for example a logic one in bit 7 causes the most

significant bit of the HCS to be inverted).

Figure 16

- 8-bit Wide, 53 Word Structure

Bit 0

Bit 7

PAYLOAD1

Word 1

Word 2

Word 3

Word 4

Word 5

Word 6

PAYLOAD48

Word 53

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