Chapter 3 Modes of Operation
MC9S08DZ128 Series Data Sheet, Rev. 1
Freescale Semiconductor
41
3.6
Stop Modes
One of two stop modes is entered upon execution of a STOP instruction when the STOPE bit in SOPT1
register is set. In both stop modes, all internal clocks are halted. The MCG module can be congured to
more information.
Table 3-1 shows all of the control bits that affect stop mode selection and the mode selected under various
conditions. The selected mode is entered following the execution of a STOP instruction.
3.6.1
Stop3 Mode
Stop3 mode is entered by executing a STOP instruction under the conditions as shown in
Table 3-1. The
states of all of the internal registers and logic, RAM contents, and I/O pin states are maintained.
Exit from stop3 is done by asserting RESET or an asynchronous interrupt pin. The asynchronous interrupt
pins are IRQ, PIA0–PIA7, PIB0–PIB7, PID0–PID7, and PIJ0–PIJ7. Exit from stop3 can also be done by
the low voltage detection (LVD) reset, the low voltage warning (LVW) interrupt, the ADC conversion
complete interrupt, the analog comparator interrupt, the real-time clock (RTC) interrupt, the MSCAN
wake-up interrupt, or the SCI receiver interrupt.
If stop3 is exited by means of the RESET pin, the MCU will be reset and operation will resume after
fetching the reset vector. Exit by means of an interrupt will result in the MCU fetching the appropriate
interrupt vector.
3.6.1.1
LVD Enabled in Stop3 Mode
The LVD system is capable of generating either an interrupt or a reset when the supply voltage drops below
the LVD voltage. If the LVD is enabled in stop (LVDE and LVDSE bits in SPMSC1 both set) at the time
the CPU executes a STOP instruction, then the voltage regulator remains active during stop mode.
For the ADC to operate or for the ACMP to be used when comparing with an internal voltage, the LVD
must be left enabled when entering stop3.
Table 3-1. Stop Mode Selection
STOPE
ENBDM 1
1 ENBDM is located in the BDCSCR, which is only accessible through BDC commands, see the Development Support chapter.
LVDE
LVDSE
PPDC
Stop Mode
0
x
Stop modes disabled; illegal opcode reset if STOP instruction executed
1
x
Stop3 with BDM enabled 2
2 When in Stop3 mode with BDM enabled, The S
IDD will be near RIDD levels because internal clocks are enabled.
1
0
Both bits must be 1
x3
3 If LVD = 1 in stop, the MCU enters stop3, regardless of the conguration of PPDC.
Stop3 with voltage regulator active
1
0
Either bit a 0
0
Stop3
1
0
Either bit a 0
1
Stop2