mc9s08qd4 Freescale Semiconductor, Inc, mc9s08qd4 Datasheet - Page 29

• Manufacturer Part Number: mc9s08qd4
• Description: Hcs08 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

the CPU executes a STOP instruction, the MCU will not enter either of the stop modes and an illegal
opcode reset is forced. The stop modes are selected by setting the appropriate bits in SPMSC2.
HCS08 devices that are designed for low voltage operation (1.8V to 3.6V) also include stop1 mode. The
MC9S08QD4 series does not include stop1 mode.
Table 3-1
3.6.1
The stop2 mode provides very low standby power consumption and maintains the contents of RAM and
the current state of all of the I/O pins. To enter stop2, the user must execute a STOP instruction with stop2
selected (PPDC = 1) and stop mode enabled (STOPE = 1). In addition, the LVD must not be enabled to
operate in stop (LVDSE = 0 or LVDE = 0). If the LVD is enabled in stop, then the MCU enters stop3 upon
the execution of the STOP instruction regardless of the state of PPDC.
Before entering stop2 mode, the user must save the contents of the I/O port registers, as well as any other
memory-mapped registers which they want to restore after exit of stop2, to locations in RAM. Upon exit
of stop2, these values can be restored by user software before pin latches are opened.
When the MCU is in stop2 mode, all internal circuits that are powered from the voltage regulator are turned
off, except for the RAM. The voltage regulator is in a low-power standby state, as is the ADC. Upon entry
into stop2, the states of the I/O pins are latched. The states are held while in stop2 mode and after exiting
stop2 mode until a logic 1 is written to PPDACK in SPMSC2.
Exit from stop2 is done by asserting either of the wake-up pins: RESET or IRQ, or by an RTI interrupt.
IRQ is always an active low input when the MCU is in stop2, regardless of how it was configured before
entering stop2.
Upon wake-up from stop2 mode, the MCU will start up as from a power-on reset (POR) except pin states
remain latched. The CPU will take the reset vector. The system and all peripherals will be in their default
reset states and must be initialized.
Freescale Semiconductor
1
Mode
Stop2
Stop3
ICS can be configured to run in stop3. Please see the ICS registers.
summarizes the behavior of the MCU in each of the stop modes.
Stop2 Mode
PPDC
Although this IRQ pin is automatically configured as active low input, the
pullup associated with the IRQ pin is not automatically enabled. Therefore,
if an external pullup is not used, the internal pullup must be enabled by
setting IRQPE in IRQSC.
1
0
CPU, Digital
Peripherals,
Standby
Flash
Off
MC9S08QD4 Series MCU Data Sheet, Rev. 3
Standby
Standby
RAM
Table 3-1. Stop Mode Behavior
Off
ICS
Off
1
NOTE
Optionally on
Disabled
ADC1
Regulator
Standby
Standby
States held Optionally on
States held Optionally on
I/O Pins
Chapter 3 Modes of Operation
RTI
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