6-10
MCF5272 User’s Manual
Programming Model
Table 6-6 details the interaction between the PDN and WK bits for the USB and USART
modules.
6.2.6 Activate Low-Power Register (ALPR)
ALPR, Figure 6-6, is used to put the MCF5272 into a low power mode (sleep or stop). A
low-power mode is activated by a write access with any data to ALPR followed by a STOP
instruction.
The sequence to enter sleep mode is as follows:
1. Set power down and wakeup enable bits in the PMR as desired; set PMR[SLPEN].
2. Set the CPU interrupt priority level in the status register (SR). Interrupts below this
level do not reactivate the CPU. Note that any interrupt will cause the processor to
exit low-power mode, but only unmasked interrupts will cause the processor to
resume operation.
3. Perform a write access with any data to ALPR.
4
SLPEN
Sleep enable. Allows the MCF5272 to be put into sleep mode in which internal clocking to the
CPU is disabled.To enter sleep mode, the user must write to the ALPR and then execute a
STOP instruction. See Section 6.2.6, “Activate Low-Power Register (ALPR).” Individual
modules may have clocking disabled through the appropriate PDN bits. After SLPEN is set, a
write access must be made to ALPR to actually enter sleep mode. D[31:0] are driven low, and
other bus signals are negated. Sleep mode is exited when an interrupt is detected from an
on-chip peripheral or one of the external interrupt pins, INT[6:1].
0 Sleep mode disabled.
1 Sleep mode enabled.
3-0
—
Reserved, should be cleared.
Table 6-6. USB and USART Power Down Modes
PDN WK
Description
0
X
Module powered up and operating normally.
1
0
Module in power down and can only be reactivated by clearing PDN.
1
1
Module in power down and can be reactivated by clearing PDN or detecting signal on the receive pins.
15
0
Field
ALPHR
Reset
0000_0000_0000_0000
R/W
Write only
Address
MBAR + 0x00E
Figure 6-6. Activate Low-Power Register (ALPR)
Table 6-5. PMR Field Descriptions (Continued)
Bits
Field
Description
Summary of Contents for DigitalDNA ColdFire MCF5272
Page 1: ...MCF5272UM D Rev 0 02 2001 MCF5272 ColdFire Integrated Microprocessor User s Manual ...
Page 38: ...xxxviii MCF5272 User s Manual TABLES Table Number Title Page Number ...
Page 58: ...1 10 MCF5272 User s Manual MCF5272 Specific Features ...
Page 90: ...2 42 MCF5272 User s Manual Exception Processing Overview ...
Page 96: ...3 6 MCF5272 User s Manual MAC Instruction Execution Timings ...
Page 158: ...5 46 MCF5272 User s Manual Motorola Recommended BDM Pinout ...
Page 184: ...7 12 MCF5272 User s Manual Interrupt Controller Registers ...
Page 338: ...13 44 MCF5272 User s Manual Application Examples ...
Page 414: ...18 6 MCF5272 User s Manual PWM Programming Model ...
Page 452: ...19 38 MCF5272 User s Manual Power Supply Pins ...
Page 482: ...20 30 MCF5272 User s Manual Reset Operation ...
Page 492: ...21 10 MCF5272 User s Manual Non IEEE 1149 1 Operation ...