PM7384 FREEDM-84P672
DATA SHEET
PMC-1990445
ISSUE 5
FRAME ENGINE AND DATA LINK MANAGER 84P672
The initiator negates FRAMEB since this the last data phase of this cycle. 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.
During clock 3, the target latches in the data element and negates TRDYB and
DEVSELB, having seen FRAMEB negated previously. The initiator negates
IRDYB and drives FRAMEB to start the next cycle. It also drives the address
onto the AD[31:0] bus and drives the C/BEB[3:0] lines with the write command.
In this example the command would indicate a burst write.
During clock 4, the initiator ceases to drive the address onto the AD[31:0] bus
and starts driving the first data element. 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 that the data is valid. 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.
During clock 5, the initiator is ready to transfer the next data element so it drives
the AD[31:0] lines with the second data element. The initiator negates FRAMEB
since this is the last data phase of this cycle. The target accepts the first data
element and negates TRDYB to indicate its is not ready for the next data
element.
During clock 6, the target is still not ready so a wait state shall be 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 element 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 tristated. The target stops driving the
AD[31:0] bus and the initiator stops driving the C/BEB[3:0] bus. This shall be the
turnaround cycle for these signals.
PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA, INC., AND FOR ITS CUSTOMERS’ INTERNAL USE
331
PMC [ PMC-SIERRA, INC ]
