
DATA SHEET
PM7367 FREEDM-32P32
ISSUE 2
PMC-1991499
FRAME ENGINE AND DATA LINK MANAGER
PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA, INC., AND FOR ITS CUSTOMER’S INTERNAL USE
289
agent is driving the signals for this clock cycle). This cycle on the PCI bus is
called the address phase.
During clock 2, the initiator ceases to drive the address onto the AD[31:0] bus
and starts driving the first data word. The initiator also drives the C/BEB[3:0]
lines with the byte enables for the write data. IRDYB is driven active by the
initiator to indicate it is ready to accept the data transfer. The target claims the
transaction by driving DEVSELB active and drives TRDYB to indicate to the
initiator that it is ready to accept the data. All subsequent cycles on the PCI bus
are called data phases.
During clock 3, the target latches in the first data word. The initiator starts to
drive the next data word onto the AD[31:0] lines.
During clock 4, the target latches in the second data word. Both the initiator and
the target indicate that they are not ready to transfer any more data by negating
the ready lines.
During clock 5, the initiator is ready to transfer the next data word so it drives the
AD[31:0] lines with the third data word and asserts IRDYB. The initiator negates
FRAMEB since this is the last data phase of this cycle. The target is still not
ready so a wait state shall be added.
During clock 6, the target is still not ready so another wait state is added.
During clock 7, the target asserts TRDYB to indicate that it is ready to complete
the transfer.
During clock 8, the target latches in the last word and negates TRDYB and
DEVSELB, having seen FRAMEB negated previously. The initiator negates
IRDYB. All of the above signals shall be driven to their inactive state in this clock
cycle except for FRAMEB which shall be tri-stated.