Revision 1.02 – April 12, 2007
S5920 – PCI Product: Signal Description
USER ADD-ON BUS PIN DESCRIPTIONS
Data Book
The following sets of signals represent the interface pins available for the Add-On bus. The following defines three
signal groups: S5920 register access signals, Pass-Thru channel signals, and general Add-On bus signals.
Table 18. Pass-Thru Data Channel Pins
Signal
Type
Description
PTMODE
in
Pass-Thru Mode. Configures the Pass-Thru data channel operation. High configures the S5920
in Passive mode allowing other devices to read/write data bus data. Low configures the S5920 in
Active mode. This mode allows the S5920 to actively drive signals and data onto the data bus.
This signal is connected to an internal pull-up.
PTATN#
PTBURST#
out
out
in
Pass-Thru Attention. Signals a decoded PCI to Pass-Thru region bus cycle. PTATN# is gener-
ated to signal that Add-On logic Pass-Thru data must be read from or written to the S5920.
Pass-Thru Burst. Informs the Add-On bus that the current Pass-Thru region decoded PCI bus
cycle is a burst access.
PTRDY#/WAIT#
Pass-Thru Ready/Pass-Thru Wait. During passive mode, the signal is referred to as PTRDY#
and is asserted low to indicate Add-On logic has read/written data in response to a PTATN# sig-
nal. During active mode operation, the signal is referred to as WAIT# and can be driven low to
insert wait states or hold the S5920 from clocking data onto the data bus. PTRDY# or WAIT# is
synchronous to ADCLK.
PTNUM[1:0]
PTBE[3:0]#
PTADR#
out
out
t/s
Pass-Thru Number. Identifies which of the four Pass-Thru regions the PTATN# read/write is
requesting. Only valid for the duration of PTATN# active. 00 = Base Address Register 1, 01 =
Base Address Register 2, 10 = Base Address Register 3, 11 = Base Address Register 4.
Pass-Thru Byte Enables. During a PCI to Pass-Thru read, PTBE[3:0] indicate which bytes of a
DWORD are to be written into. During a PCI to Pass-Thru write, these pins indicate which bytes
of a DWORD are valid to read. PTBE[3:0]# are only valid while PTATN# is asserted.
Pass-Thru Address. Is an input when in passive mode. When asserted, the 32-bit Pass-Thru
address register contents are driven onto the DQ[31:0] bus. All other Add-On control signals
must be inactive during the assertion of PTADR# in passive mode. In active mode, becomes an
output and indicates a Pass-Thru address is on the DQ bus. The DQMODE signal does not affect
DQ bus width while the Pass-Thru address is driven.
PTWR
out
out
Pass-Thru Write. This signal indicates whether the current PCI to Pass-Thru bus transaction is a
read or write cycle. Valid only when PTATN# is active.
DXFER#
ACTIVE Transfer complete. When in ACTIVE mode, this output is asserted at the end of every 8-
16- or 32-bit data transfer cycle. This signal is not used in Passive mode.
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AMCC [ APPLIED MICRO CIRCUITS CORPORATION ]
