PM7367 datasheet(235/323 Pages) PMC

235 / 323 page

PM7367 FREEDM-32P32

DATA SHEET

PMC-1991499

ISSUE 2

FRAME ENGINE AND DATA LINK MANAGER

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

221

whose channel transfer size is set to one block (XFER[2:0] = 'b000).

BURST[2:0] has no effect when BURSTEN is set low, nor on channels

configured with other transfer sizes. BURST[2:0] defines the maximum

number of 16 byte blocks, less one, that is transferred in each DMA

transaction. Thus, the minimum number of blocks is one (16 bytes) and the

maximum is eight (128 bytes).

BURSTEN:

The burst length enable bit (BURSTEN) controls the use of BURST[2:0] in

determining the amount of data requested in a single DMA transaction for

channels whose channel transfer size is set to one block (XFER[2:0] = 'b000).

BURSTEN has no effect on channels configured with other transfer sizes.

When BURSTEN is set high, the maximum size of DMA transfer is limited by

BURST[2:0]. The transmit HDLC processor may combine several channel

transfer size amounts into a single transaction. When BURSTEN is set low,

the amount of data in a DMA transfer is limited to one block.

TSTD:

The telecom standard bit (TSTD) controls the bit ordering of the HDLC data

transferred from the PCI host. When TSTD is set low, the least significant bit

of the each byte on the PCI bus (AD[0], AD[8], AD[16] and AD[24]) is the first

HDLC bit transmitted and the most significant bit of each byte (AD[7], AD[15],

AD[23] and AD[31]) is the last HDLC bit transmitted (datacom standard).

When TSTD is set high, AD[0], AD[8], AD[16] and AD[24] are the last HDLC

bit transmitted and AD[7], AD[15], AD[23] and AD[31] are the first HDLC bit

transmitted (telecom standard).

BIT8:

The least significant stuff control bit (BIT8) carries the value placed in the

least significant bit of each octet when the HDLC processor is configured

(7BIT set high) to stuff the least significant bit of each octet in the

corresponding transmit link (TD[n]). When BIT8 is set high, the least

significant bit (last bit of each octet transmitted) is forced high. When BIT8 is

set low, the least significant bit is forced low. BIT8 is ignored when 7BIT is set

low.

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