pi7c8150b Pericom Semiconductor Corporation, pi7c8150b Datasheet - Page 71

• Manufacturer Part Number: pi7c8150b
• Description: Asynchronous 2-port Pci Bridge
• Manufacturer: Pericom Semiconductor Corporation

06-0044
12.2
12.3
P_RESET_L asserting and de-asserting edges can be asynchronous to P_CLK and
S_CLKOUT. PI7C8150B is not accessible during P_RESET_L. After P_RESET_L is de-
asserted, PI7C8150B remains inaccessible for 16 PCI clocks before the first configuration
transaction can be accepted.
SECONDARY INTERFACE RESET
PI7C8150B is responsible for driving the secondary bus reset signals, S_RESET_L.
PI7C8150B asserts S_RESET_L when any of the following conditions are met:
Signal P_RESET_L is asserted. Signal S_RESET_L remains asserted as long as
P_RESET_L is asserted and does not de-assert until P_RESET_L is de-asserted.
The secondary reset bit in the bridge control register is set. Signal S_RESET_L
remains asserted until a configuration write operation clears the secondary reset bit.
S_RESET_L pin is asserted. When S_RESET_L is asserted, PI7C8150B immediately 3-
states all the secondary PCI interface signals associated with the secondary port. The
S_RESET_L in asserting and de-asserting edges can be asynchronous to P_CLK.
When S_RESET_L is asserted, all secondary PCI interface control signals, including the
secondary grant outputs, are immediately 3-stated. Signals S1_AD, S1_CBE[3:0]#, S_PAR
are driven low for the duration of S_RESET_L assertion. All posted write and delayed
transaction data buffers are reset. Therefore, any transactions residing inside the buffers at
the time of secondary reset are discarded.
When S_RESET_L is asserted by means of the secondary reset bit, PI7C8150B remains
accessible during secondary interface reset and continues to respond to accesses to its
configuration space from the primary interface.
CHIP RESET
The chip reset bit in the diagnostic control register can be used to reset the PI7C8150B and
the secondary bus.
When the chip reset bit is set, all registers and chip state are reset and all signals are
tristated. S_RESET_L is asserted and the secondary reset bit is automatically set.
S_RESET_L remains asserted until a configuration write operation clears the secondary
reset bit and the serial clock mask has been shifted in. Within 20 PCI clock cycles after
completion of the configuration write operation, PI7C8150B’s reset bit automatically clears
and PI7C8150B is ready for configuration.
During reset, PI7C8150B is inaccessible.
PI7C8150B performs a chip reset.
Registers that have default values are reset.
Page 71 of 108
ASYNCHRONOUS 2-PORT PCI-TO-PCI BRIDGE
APRIL 2006 – Revision 2.02
PI7C8150B