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3.2.2 Wait mode
Wait mode is entered by executing a WAIT instruction. Upon execution of the WAIT
instruction, the CPU enters a low-power state in which it is not clocked. The I bit in CCR
is cleared when the CPU enters the wait mode, enabling interrupts. When an interrupt
request occurs, the CPU exits the wait mode and resumes processing, beginning with the
stacking operations leading to the interrupt service routine.
While the MCU is in wait mode, there are some restrictions on which background debug
commands can be used. Only the BACKGROUND command and memory-access-with-
status commands are available when the MCU is in wait mode. The memory-access-with-
status commands do not allow memory access, but they report an error indicating that the
MCU is in either stop or wait mode. The BACKGROUND command can be used to
wake the MCU from wait mode and enter active background mode.
3.2.3 Stop3 mode
To enter stop3, the user must execute a STOP instruction with stop mode enabled
(SOPT1[STOPE] = 1). Upon entering the stop3 mode, all of the clocks in the MCU are
halted by default, but OSC clock and internal reference clock can be turned on by setting
the ICS control registers. The ICS enters its standby state, as does the voltage regulator
and the ADC. The states of all of the internal registers and logic, as well as the RAM
content, are maintained. The I/O pin states are not latched at the pin. Instead they are
maintained by virtue of the states of the internal logic driving the pins being maintained.
Exit from stop3 is done by asserting reset or through an interrupt. The interrupt include
the asynchronous interrupt from the IRQ or KBI pins, the SCI receive interrupt, the ADC,
ACMP, TSI , IIC or LVI interrupt and the real-time interrupt.
If stop3 is exited by means of the RESET pin, then the MCU will be reset and operation
will resume after taking the reset vector. Exit by means of an asynchronous interrupt or
the real-time interrupt will result in the MCU taking the appropriate interrupt vector.
The LPO (≈1 kHz) for the real-time counter clock allows a wakeup from stop3 mode with
no external components. When RTC_SC2[RTCPS] is clear, the real-time counter clock
function is disabled.
MC9S08PT60 Reference Manual, Rev. 4, 08/2014
56
Freescale Semiconductor, Inc.
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