Revision 1.02 – June 27, 2006
S5935 – PCI Product
Data Book
Register Access Pins (Continued)
Signal
Type
Description
SELECT#
in
Select for the Add-On interface. This signal must be driven low for any write or read access to the Add-
On interface registers. This signal must be stable during the assertion of command signals WR# or
RD#.
WR#
RD#
in
in
in
Write strobe. This pin, when asserted in conjunction with the SELECT# pin, causes the writing of one
of the internal registers. The specific register and operand size are identified through address pins
ADR[6:2] and the byte enables, BE[3:0]#.
Read strobe. This pin, when asserted in conjunction with the SELECT# pin, causes the reading of one
of the internal registers. The specific register and operand size are identified through address pins
ADR[6:2] and the byte enables BE[3:0]#.
MODE
This pin control whether the S5935 data accesses on the DQ bus are to be 32-bits wide (MODE = low)
or 16-bits wide (MODE = high). When in the 16 bit mode, the signal BE3# is reassigned as the address
signal ADR1.
FIFO Access Pins
Signal
Type
Description
WRFIFO#
in
Write FIFO. This signal provides a method to directly write the FIFO without having to generate the
SELECT# signal or the ADR[6:2] value of [01000b] to access the FIFO. Access width is either 32 bits
or 16 bits depending on the data bus size available. This signal is intended for implementing PCI DMA
transfers with the Add-On system.
RDFIFO#
in
Read FIFO. This signal provides a method to directly read the FIFO without having to generate the
SELECT# signal or the ADR[6:2] value of [01000b] to access the FIFO. Access width is either 32 bits
or 16 bits, depending on the data bus size defined by the MODE pin. This signal is intended for imple-
menting PCI DMA transfers with the Add-On system. WRFULL out Write FIFO full. This pin indicates
whether the Add-On-to-PCI bus FIFO is able to accept more data. This pin is intended to be used to
implement DMA hardware on the Add-On system bus. A logic low output from this pin can be used to
represent a DMA write (Add-On to-PCI FIFO) request.
RDEMPTY
out
Read FIFO Empty. This pin indicates whether the read FIFO (PCI-to-Add-On FIFO) contains data.
This pin is intended to be used by the Add-On system to control DMA transfers from the PCI bus to the
Add-On system bus. A logic low from this pin can be used to represent a DMA (PCI-to-Add-On FIFO)
request.
Pass-Thru Interface Pins
Signal
Type
Description
PTATN#
out
Pass-Thru Attention. This signal identifies that an active PCI bus cycle has been decoded and data
must be read from or written to the Pass-Thru Data Register.
PTBURST#
PTRDY#
out
in
Pass-Thru Burst. This signal identifies PCI bus operations involving the current Pass-Thru cycle as
requesting burst access.
Pass-Thru Ready. This input indicates when Add-On logic has completed a Pass-Thru cycle and
another may be initiated.
PTNUM[1:0]
out
Pass-Thru Number. These signals identify which of the four base address registers decoded a Pass-
Thru bus activity. These bits are only meaningful when signal PTATN# is active. A value of 00 corre-
sponds to Base Address Register 1, a value of 01 for Base Address Register 2, and so on.
PTBE[3:0]#
out
Pass-Thru Byte Enables. These signals indicate which bytes are requested for a given Pass-Thru
operation. They are valid during the presence of signal PTATN# active.
AMCC Confidential and Proprietary
DS1527
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AMCC [ APPLIED MICRO CIRCUITS CORPORATION ]
