PM7385 FREEDM-84A672
DATA SHEET
PMC-1990114
ISSUE 6
84 LINK, 672 CHANNEL FRAME ENGINE AND DATA LINK MANAGER
WITH ANY-PHY PACKET INTERFACE
Figure 21 – Transmit APPI Timing (Special Conditions)
TXCLK
TRDY
Dev 3
Dev 5
TXDATA[15:0]
TSX
CH 0
D0
CH 671
D0
D1
D2
CH 2
D0
TEOP
TMOD
TERR
Figure 21 shows two special conditions – (1) the transfer of a one word packet
illustrating how the external controller must wait until TRDY has been sampled
high before the next data transfer can begin, and (2) the transfer of a packet
which completes when TRDY is set low illustrating that although the packet has
been completely transferred, the external controller must still wait until TRDY has
been sampled high before the next data transfer can begin.
The first data transfer is a single word packet for FREEDM-84A672 device 3,
channel 0. The FREEDM-84A672 asserts TRDY high one TXCLK cycle after
TSX is sampled high. The Tx APPI protocol dictates that the external controller
must wait until TRDY is sampled high before beginning the next data transfer for
FREEDM-84A672 device 5, channel 671. The external controller must hold the
last valid word on TXDATA[15:0] until TRDY is sampled high. In this case, that
data is a don’t care. The FREEDM-84A672 tristates the TRDY signal one TXCLK
cycle after it has been driven high.
The second transfer is a three word packet which completes transfer in the same
TXCLK cycle that TRDY is sampled low by the external controller. Again, the
external controller must hold the last valid word on TXDATA[15:0] until TRDY is
sampled high. In this case, that data is D2, the last word of the packet. The
FREEDM-84A672 may drive TRDY low for an indeterminate number of TXCLK
cycles. During this time, the external controller must wait and is not permitted to
begin another burst data transfer until TRDY is sampled high. When the external
controller samples TRDY high, the current burst transfer is deemed to be
complete and the external controller may begin the next data transfer. The
FREEDM-84A672 tristates the TRDY signal one TXCLK cycle after it has been
driven high.
PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA, INC., AND FOR ITS CUSTOMERS’ INTERNAL USE
216
PMC [ PMC-SIERRA, INC ]
