S5920Q Applied Micro Circuits Corporation, S5920Q Datasheet - Page 131

• Manufacturer Part Number: S5920Q
• Manufacturer: Applied Micro Circuits Corporation

Specifications of S5920Q

• Operating Temperature (min): 0C
• Operating Temperature Classification: Commercial
• Operating Temperature (max): 70C
• Package Type: PQFP
• Rad Hardened: No
• Lead Free Status / Rohs Status: Not Compliant

S5920 – PCI Product: Pass-Thru Operation
Clock 1: Pass-Thru signals PTATN#, PTBURST#,
PTNUM[1:0], PTWR and PTBE[3:0] are driven to indi-
cate what action is required by Add-On logic. These
status signals are valid only when PTATN# is active.
Add-On logic can decode status signals upon the
assertion of PTATN#.
PTATN# Asserted. Indicates Pass-Thru access is
pending.
PTBURST# Asserted. The access has multiple data
phases.
PTNUM[1:0] 0h. Indicates the access is to Pass-Thru
region 3.
PTWR Asserted. Indicates the access is a write.
PTBE[3:0]# D1. Indicates valid bytes for the first data
transfer.
C l o c k 2 : A d d - O n l o g i c s a m p l e s PTAT N # a n d
PTBURST# asserted, indicating the start of a burst.
The Add-On asserts PTADR# to read the Pass-Thru
Address Register. As it is not ready to receive any data
yet, it does not initiate a data read.
Clock 3: Add-on logic latches the address. RD#,
BE[3:0]#, ADR[6:2], and SELECT# inputs are asserted
to select the Pass-Thru Data Register during the next
clock. PTRDY# is also asserted to indicate the com-
pletion of the first data phase.
Clock 4: As the S5920 sampled PTRDY# asserted,
the first data phase is completed DATA1 is driven on
the DQ bus, a result of the read from the previous
clock cycle. The PTBE# outputs are updated to indi-
cate which bytes are valid for the second transfer.
Add-on logic is not fast enough to store the next data,
so a wait state is activated by deasserting PTRDY#.
RD# is also deasserted.
Clock 5: Add-On logic uses the rising edge of this
clock to store DATA1. PTRDY# is sampled deas-
serted, so a wait state is activated. PTRDY# is
asserted to indicate that the Add-On is ready to accept
the next data transfer. RD# is also asserted, request-
ing DATA2 to be driven during the next clock cycle.
Clock 6: PTRDY# is sampled asserted, thus complet-
ing the current data-phase. DATA2 is driven on the DQ
bus, a result of a read during the previous clock cycle.
The PTBE# outputs are updated to indicate which
bytes are valid for the third transfer. Add-on logic is not
fast enough to store the next data, so a wait state is
activated by deasserting PTRDY#. RD# is also
deasserted.
Clock 7: Add-On logic uses the rising edge of this
clock to store DATA2. PTRDY# is sampled deas-
serted, so a wait state is activated. PTRDY# is
asserted to indicate that the Add-On is ready to accept
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the next data transfer. RD# is also asserted, request-
ing DATA3 to be driven during the next clock cycle.
Clock 8: PTRDY# is sampled asserted, thus complet-
ing the current data-phase. DATA3 is driven on the DQ
bus, a result of a read during the previous cycle. The
PTBE# outputs are updated to indicate which bytes
are valid for the fourth transfer. Add-On logic is not fast
enough to store the next data, so a wait state is acti-
v a t e d b y d e a s s e r t i n g P T R D Y # . R D # i s a l s o
deasserted.
Clock 9: Add-On logic uses the rising edge of this
clock to store DATA3. PTRDY# is sampled deas-
serted, so a wait state is activated. PTRDY# is
asserted to indicate that the Add-On is ready to accept
the next data transfer. RD# is also asserted, request-
ing DATA4 to be driven during the next clock cycle.
Clock 10: PTRDY# is sampled asserted, thus com-
pleting the current data-phase. PTBURST# is
deasserted, indicating that only one DWORD is left for
transfer. DATA4 is driven on the Add-On DQ bus, a
result of a read during the previous clock cycle. The
PTBE# outputs are updated to indicate which bytes
are valid for the last transfer. Add-On logic is not fast
enough to store the next data, so a wait state is acti-
v a t e d b y d e a s s e r t i n g P T R D Y # . R D # i s a l s o
deasserted.
Clock 11: Add-On logic uses the rising edge of this
clock to store DATA4. PTRDY# is sampled deas-
serted, so a wait state is activated. PTRDY# is
asserted to indicate that the add-on is ready to accept
the last data transfer. The add-on knows this is the last
transfer as it has sampled PTBURST# deasserted and
PTATN# asserted. RD# is also asserted, requesting
DATA5 to be driven during the next clock cycle.
Clock 12: PTRDY# is sampled asserted, indicating
that the last transfer was completed. As a result,
PTATN# is deasserted. As the Add-On has also fin-
ished its transfer, it deasserts RD#, SELECT#,
BE[3:0]#. The last data, DATA5, is driven on the Add-
On DQ bus.
Clock 13: Add-On logic uses the rising edge of this
clock to store DATA5. As PTATN# is deasserted, the
Pass-Thru access is complete, and the S5920 can
accept new Pass-Thru accesses starting on the next
clock. The other Pass-Thru signals can also change
state (in anticipation of a new transfer).
Pass-Thru Burst Reads
A Pass-Thru burst read operation occurs when a PCI
initiator reads multiple DWORDs from a Pass-Thru
region. A burst transfer consists of a single address
and multiple data phases. The S5920 stores the PCI
Revision 1.02 – April 12, 2007
Data Book
DS1596
131