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Operating Modes and Clocking
MPC5644A Microcontroller Reference Manual, Rev. 6
114
Freescale Semiconductor
5.3.4.5.2
Halt clock gating
Software controlled clock gating can be done via the centralized halt mechanism. The SIU_HLT register
bits corresponding to individual modules are configured to determine which modules are clock gated.
The SIU_HLT register bits are used to drive a stop request signal to the modules. After the module
completes a clean shut down, the module asserts a stop acknowledge handshake signal that is used to gate
the clock to the module (see
). The stop acknowledge signals are also captured in the
SIU_HLTACK read-only register bits.
The halted modules recover when the corresponding SIU_HLT register bit is cleared by software. Once
the bit is cleared, logic will re-enable the clocks to the modules and then negate the stop request signal after
the required timing has been met.
5.3.4.5.3
CPU clock gating
The SIU_HLT register has a bit to halt the clock to the CPU, but in order to prevent accidental CPU halting,
a stop request is only activated if the CPU is in wait state due to the execution of the WAIT instruction.
NOTE
To gate the CPU clock you need to first program the SIU_HLT register bit
assigned for CPU and then execute the CPU WAIT instruction.
Table 5-2. MDIS support
1
1
The MDIS bit default reset value is zero.
Block name
Register name
Bit name
DSPI_B
DSPI_B_MCR
MDIS
DSPI_C
DSPI_C_MCR
MDIS
DSPI_D
DSPI_D_MCR
MDIS
EBI
EBI_MCR
MDIS
eTPU
ETPUECR_1
MDIS
FlexCAN A
FLEXCAN_A_MCR
MDIS
FlexCAN B
FLEXCAN_B_MCR
MDIS
FlexCAN C
FLEXCAN_C_MCR
MDIS
eMIOS
EMIOS_MCR
MDIS
eSCI_A
eSCI_A_SCICR3
MDIS
eSCI_B
eSCI_B_SCICR3
MDIS
eSCI_C
eSCI_C_SCICR3
MDIS
Decimation Filter
DECFILTERMCR
MDIS
Red Line Module
TBD
MDIS
NPC
NPC_PCR
MCKO_EN, MCKO_GT
Flash Memory Array
FLASH_MCR
STOP
Содержание MPC5644A
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Страница 56: ...Memory Map MPC5644A Microcontroller Reference Manual Rev 6 56 Freescale Semiconductor...
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