Revision 5.01 – November 30, 2005
S5335 – PCI Bus Controller, 3.3V
Data Sheet
One consideration needs to be taken when using the
FIFO direct access signals and letting the S5335 do
byte lane steering internally. The default condition
used to advance the FIFO is byte 0. This must be
changed to byte 2 or 3. When MODE is configured for
a 16-bit Add-On bus, the first 16-bit cycle to the FIFO
always accesses the low 16-bits. If the FIFO advance
condition is left at byte 0, the FIFO advances after the
first 16-bit cycle and the data in the upper 16-bits is
directed to the next FIFO location, shifting the data.
downloaded from non-volatile memory after reset, the
bus mastering initialization method can not be
changed. Access to the bus master address and trans-
fer count registers cannot be alternated between the
PCI bus and the Add-On interface during operation.
Bits 6 and 5 in location 45h enable FIFO register
accesses using the RDFIFO#, WRFIFO#, RD# and
WR# inputs synchronous to BPCLK. For synchronous
operation, RDFIFO#, WRFIFO#, RD# and WR# oper-
ate as enables, using BPCLK to clock data.
Some applications hold the RDFIFO# and WRFIFO#
inputs active for a synchronous interface. In 16-bit
mode, designs must avoid writing to a full FIFO. The
data for the write is lost, but the internal mechanism to
direct the 16-bit external data bus to the upper 16-bits
of the FIFO register is triggered. This creates a situa-
tion where the FIFO is out of step. The next 16-bit
FIFO write is directed to the upper 16-bits of the FIFO,
and the FIFO advances incorrectly. The WRFULL out-
put should be used to gate the WRFIFO# input to
avoid this situation. A similar problem can occur if
Add-On logic attempts to read an empty FIFO in 16-bit
mode. RDEMPTY should be used to gate the
RDFIFO# input to avoid problems with the FIFO get-
ting out of step. In 32-bit mode (MODE = low), these
situations do not occur.
Location 45h Configuration Bits
Bit 7 Bus Master Register Access
0
Address and transfer count registers only accessi-
ble from the Add-On interface
1
Address and transfer count registers only accessi-
ble from the PCI interface (default)
Bit 6 RDFIFO#, RD# Operation
0
1
Enable - RDFIFO# and RD# functions.
Not allowed. Must be 0.
Bit 5 WRFIFO#, WR# Operation
0
1
Enable - WRFIFO# and WR# functions.
Not allowed. Must be 0.
If FIFO accesses are done without the direct access
signals with MODE configured for 16-bits (using ADR,
SELECT#, etc.), external hardware must toggle ADR1
between consecutive 16-bit bus cycles. The FIFO
advance condition must be set to correspond to the
order the application accesses the upper and lower
words in the FIFO register.
Bit 0 Target Latency Timer Enable
0
1
Disable PCI Latency Timer Time Out - Will not dis-
connect with retry if cannot issue TRDY in speci-
fied time
Enable PCI Latency Timer Time Out - Will be PCI
2.1 compliant
CONFIGURATION
The FIFO configuration takes place during initialization
and during operation. During initialization, the bus
master register access rights are defined. During oper-
ation, FIFO advance conditions, endian conversion,
and bus mastering capabilities are defined. The follow-
ing section describes the bits and registers which are
involved with controlling and monitoring FIFO
operation.
FIFO Status and Control Bits
The FIFO status can be monitored and the FIFO oper-
ation controlled from the PCI Operation Registers and/
or the Add-On Operation Registers. The FIFO register
resides at offset 20h in the PCI and Add-On Operation
Registers.
The Bus Master Control/Status (MCSR) PCI Operation
register allows a PCI host to monitor FIFO activity and
control FIFO operation. Reset controls allow the PCI to
Add-On FIFO and Add-On to PCI FIFO flags to be
reset (individually). Status bits indicate if the PCI to
Add-On FIFO is empty, has four or more open spaces,
or is full. Status bits also indicate if the Add-On to PCI
FIFO is empty, has four or more full locations or is full.
Finally, FIFO PCI bus mastering is monitored/con-
trolled though this register.
FIFO Setup During Initialization
Location 45h in an external non-volatile memory may
be used to configure the S5335 FIFO during initializa-
tion. If no external non-volatile memory is used, FIFO
operation is disabled.
The value of bit 7 in location 45h determines if the
address and transfer count registers used in bus mas-
tering are accessible from the PCI bus or from the
Add-On bus. Once the configuration information is
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