14-8
MPC8240 Integrated Processor User’s Manual
Peripheral Logic Power Management
In doze, nap, and sleep modes, the peripheral logic always monitors the internal bus request
signal from the processor core. When it is asserted, for example due to the occurrence of
the decrementer exception, the peripheral logic exits its low power state and goes back to
the full-power state to service the request.
The MPC8240 does not support the broadcast of PCI special cycles related to low-power
operation. Thus, the PMCR1[NO_NAP_MSG] and PMCR1[NO_SLEEP_MSG] bits must
be set by initialization software (they are cleared upon reset) to indicate that the MPC8240
does not broadcast the HALT or sleep message commands on the PCI bus before entering
the nap or sleep modes, respectively.
Table 14-2 summarizes the functionality and transition criteria of the peripheral logic block
in all power states.
.
Table 14-2. Peripheral Logic Power Modes Summary
PM
Mode
Functioning Units
Activation Method
Full-Power Wake Up
Method
Full
power
All units active
—
—
Doze
PCI address decoding and bus arbiter
System RAM refreshing
Processor bus request and NMI monitoring
EPIC unit
I
2
C unit
PLL
Controlled by software
(write to PMCR1)
PCI access to memory
Processor bus request
Assertion of NMI
1
Interrupt to EPIC
Hard Reset
1
Programmable option based on value of PICR1[MCP_EN] = 1
Nap
PCI address decoding and bus arbiter
System RAM refreshing
Processor bus request and NMI monitoring
EPIC unit
I
2
C unit
PLL
Controlled by software
(write to PMCR1) and
processor core in nap or
sleep mode (QREQ
asserted)
PCI access to memory
2
Processor bus request
Assertion of NMI
Interrupt to EPIC
Hard Reset
2
A PCI access to memory in nap mode does not cause QACK to negate; consequently, it does not wake up the
processor core, and the processor core won’t snoop this access. After servicing the PCI access, the peripheral
logic automatically returns to the nap mode.
Sleep
PCI bus arbiter
System RAM refreshing (can be disabled)
Processor bus request and NMI monitoring
EPIC unit
I
2
C unit
PLL (can be disabled)
Controlled by software
(write to PMCR1) and
processor core in nap or
sleep mode (QREQ
asserted)
Processor bus request
Assertion of NMI
Interrupt to EPIC
Hard Reset
Summary of Contents for MPC8240
Page 1: ...MPC8240UM D Rev 1 1 2001 MPC8240 Integrated Processor User s Manual ...
Page 38: ...xviii MPC8240 Integrated Processor User s Manual TABLES Table Number Title Page Number ...
Page 48: ...xlviii MPC8240 Integrated Processor User s Manual Acronyms and Abbreviations ...
Page 312: ...6 94 MPC8240 Integrated Processor User s Manual ROM Flash Interface Operation ...
Page 348: ...7 36 MPC8240 Integrated Processor User s Manual PCI Host and Agent Modes ...
Page 372: ...8 24 MPC8240 Integrated Processor User s Manual DMA Register Descriptions ...
Page 394: ...9 22 MPC8240 Integrated Processor User s Manual I2O Interface ...
Page 412: ...10 18 MPC8240 Integrated Processor User s Manual Programming Guidelines ...
Page 454: ...12 14 MPC8240 Integrated Processor User s Manual Internal Arbitration ...
Page 466: ...13 12 MPC8240 Integrated Processor User s Manual Exception Latencies ...
Page 516: ...16 14 Watchpoint Trigger Applications ...
Page 538: ...B 16 MPC8240 Integrated Processor User s Manual Setting the Endian Mode of Operation ...
Page 546: ...C 8 MPC8240 Integrated Processor User s Manual ...
Page 640: ...INDEX Index 16 MPC8240 Integrated Processor User s Manual ...