3. Clocking and Reset Options
47
Tsi310 User Manual
80B6020_MA001_05
The Tsi310 does not have I/O pins for the M66EN or PCIXCAP signals on its primary interface.
The bridge adjusts its internal configuration (including its internal PLLs, if appropriate) solely
on the basis of the initialization pattern it detects on the signals P_DEVSEL#, P_STOP#, and
P_TRDY# at the rising edge of P_RST#. If the internal PLL is used (the bus is configured in
PCI-X mode), a maximum of 100
s from the rising edge of P_RST# is required to lock the PLL
to the frequency of the clock supplied on the P_CLK input.
3.3.2
Secondary Interface
The secondary interface is also capable of operating in either conventional PCI mode or in
PCI-X mode, at any of the defined frequency ranges. Since the Tsi310 acts as the central
resource for the secondary bus, it controls the mode and frequency determination process. As
recommended by Section 14.2 of the
PCI-X Addendum to PCI Local Bus Specification
(Revision 1.0a)
, the bridge uses a programmable pull-up circuit to accomplish this.
shows the programmable pull-up circuit and the structure of the network that is connected to the
S_PCIXCAP input of the bridge. Examples of the connections that are expected when
PCI-X 66, PCI-X 133, and conventional PCI clients are attached to the bus are also shown (for
more information, see the
PCI-X Addendum
). There are two pull-up resistors in the circuit. The
first is an external weak pull-up whose value of 56k
is selected to set the voltage of the
S_PCIXCAP input below its low threshold when a PCI-X 66 client is attached. The second is a
strong pull-up, externally wired between the S_PCIXCAP and S_PCIXCAP_PU pins on the
module. Its value of 1k
is selected to set the voltage of the S_PCIXCAP input above its high
threshold when all clients on the bus are only PCI-X 66 capable.
During the mode and frequency determination process, the S_PCIXCAP_PU driver is initially
disabled, effectively removing the strong pull-up resistor from the circuit. The Tsi310 begins by
sampling the value on its S_PCIXCAP input. If it detects a b’0’ value, one or more clients have
either pulled the network to ground (if they are PCI-X 66 capable) or tied it to ground (if they
are only capable of conventional PCI operation). To distinguish between these two cases, the
bridge then enables its S_PCIXCAP_PU driver to put the strong pull-up into the circuit. If, after
a sufficient time, the S_PCIXCAP input remains at a b’0’ value, the network must be tied to
ground by one or more clients, and the bus is initialized to the conventional PCI mode. If the
network can be pulled up, one or more clients are capable of only PCI-X 66 operation (and there
are no conventional PCI devices), so the bus is initialized to PCI-X 66 mode.
If the Tsi310 initially samples a b’1’ value on the S_PCIXCAP input, then all clients on the bus
are capable of PCI-X 133 operation. The bridge then samples the S_SEL100 input to distinguish
between the 66-100 MHz and the 100-133 MHz clock frequency ranges. If it detects a b’1’
value on the S_SEL100 input, the bus is initialized with the PCI-X 100 initialization pattern. If
the value is b’0’, the PCI-X 133 initialization pattern is used. These two ranges allow
adjustment of the clock frequency to account for bus loading conditions.
Содержание Tsi310TM
Страница 8: ...Contents 8 Tsi310 User Manual 80B6020_MA001_05...
Страница 10: ...List of Figures 10 Tsi310 User Manual 80B6020_MA001_05...
Страница 12: ...List of Tables 12 Tsi310 User Manual 80B6020_MA001_05...
Страница 18: ...18 Tsi310 User Manual 80B6020_MA001_05...
Страница 44: ...2 Bus Operation 44 Tsi310 User Manual 80B6020_MA001_05...
Страница 58: ...3 Clocking and Reset Options 58 Tsi310 User Manual 80B6020_MA001_05...
Страница 62: ...4 Transaction Ordering 62 Tsi310 User Manual 80B6020_MA001_05...
Страница 150: ...5 Configuration Registers 150 Tsi310 User Manual 80B6020_MA001_05...
Страница 170: ...6 Signals and Pinout 170 Tsi310 User Manual 80B6020_MA001_05...
Страница 190: ...7 JTAG Boundary Scan 190 Tsi310 User Manual 80B6020_MA001_05...
Страница 196: ...8 Electrical Characteristics 196 Tsi310 User Manual 80B6020_MA001_05...
Страница 200: ...9 Package Information 200 Tsi310 User Manual 80B6020_MA001_05...
Страница 202: ...A Ordering Information 202 Tsi310 User Manual 80B6020_MA001_05...
Страница 206: ...Index 206 Tsi310 User Manual 80B6020_MA001_05...