CPC700 User’s Manual—Preliminary
2-3
2.2 PCI Bus Interface Signals
Signal Name
Active
Level
I / O
Description
AD[31:0]
High
I/O
Address/Data Bus: Address and data are multiplexed onto the same
PCI pins. A bus transaction consists of an address phase followed by
one or more data phases.
C/BE_N[3:0] Low
I/O
Bus command and Byte Enables: Command and Byte Enables are
multiplexed on the same pins. During the address phase of a
transaction, C/BE[0:3] define the bus command and during the data
phase they carry the bus byte enables.
PAR
High
I/O
Parity: Even parity across AD[0:31] and C/BE_N[0:3]. Parity is stable
and valid one clock after the address phase.
FRAME_N
Low
I/O
Frame: Driven by the current master to identify the beginning and
duration of an access.
IRDY_N
Low
I/O
Initiator Ready: Indicates the initiating agent’s ability to complete the
current data phase of the transaction.
TRDY_N Low
I/O
Target Ready: Indicates the Target agent’s ability to complete the
current data phase of the transaction.
STOP_N
Low
I/O
STOP: Indicates the current target is requesting the master to stop the
current transaction.
DEVSEL_N
Low
I/O
Device Select: When actively driven, indicates the driving device has
decoded its address as the target of the current access.
IDSEL
High
I
Initialization Device Select: Used as a chip select during configuration
read and write transactions
SERR_N
Low
I/O
System Error: May be used for reporting address parity errors, data
parity errors on special cycle commands, or other error where the result
will be catastrophic.
PERR_N
Low
I/O
Parity Error: Data parity error.
PCI_CLK --
I
Asynchronous PCI Clock: Clock input required for use when the PCI
bus is run asynchronously from the processor bus. When operating in
synchronous mode, this pin is not used and should be tied low.
RST_N Low
O
PCI RESET: This output may be used as the reset to PCI bus slots when
the CPC700 is used as the primary host bridge. This signal will be
asserted during three scenarios:
1.
Power on Reset: Following the deasertion of SYS_RESET_N,
RST_N will remain active for a period of 500us while the internal
PLLs lock after which, this signal will be deaserted.
2.
Software Control: Setting PCI Bridge Options 2 register bit 12 high
will cause RST_N to assert. Resetting bit 12 to zero will deassert
RST_N.
3.
PLL Tuning Bits Change: If the PLL tuning bits are changed under
software control, the CPC700 will enter the reset state similar to a
power on reset sequence. RST_N will remain asserted for 500us.
Summary of Contents for CPC700
Page 10: ...Table of Contents x Table of Contents...
Page 16: ...Tables xvi List of Tables...
Page 28: ...1 12 CPC700 User s Manual Preliminary...
Page 72: ...3 36 Processor Interface...
Page 132: ...4 60 Memory Controller...
Page 184: ...5 52 PCI Interface...
Page 194: ...6 10 Clock Power Management and Reset...
Page 224: ...8 18 IIC...
Page 244: ...10 10 Interrupt Controller...
Page 246: ...I 11 2 JTAG...
Page 250: ...12 4 Processor Local Bus PLB...
Page 262: ...14 10 Register Summary...
Page 267: ...CPC700 User s Manual Preliminary...