RELEASED
PM7366 FREEDM-8
DATA SHEET
PMC-1970930
ISSUE 4
FRAME ENGINE AND DATA LINK MANAGER
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.
PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA,INC., AND FOR ITS CUSTOMERS’ INTERNAL USE
188
PMC [ PMC-SIERRA, INC ]
