Chapter 3 Modes of Operation
MC9S08SG32 Data Sheet, Rev. 8
Freescale Semiconductor
35
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.
Stop3 can be exited by asserting RESET, or by an interrupt from one of the following sources: the real-time
counter (RTC), LVD system, ACMP, ADC, SCI or any pin interrupts.
If stop3 is exited by means of the RESET pin, then the MCU is reset and operation will resume after taking
the reset vector. Exit by means of one of the internal interrupt sources results in the MCU taking 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
Detect (LVD) System”. 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 in stop mode, the LVD must be enabled when entering stop3.
For the ACMP to operate in stop mode with compare to internal bandgap option, the LVD must be enabled
when entering stop3.
3.6.1.2
Active BDM Enabled in Stop3 Mode
Entry into the active background mode from run mode is enabled if ENBDM in BDCSCR is set. This
STOP instruction, the system clocks to the background debug logic remain active when the MCU enters
stop mode. Because of this, background debug communication remains possible. In addition, the voltage
regulator does not enter its low-power standby state but maintains full internal regulation.
Table 3-1. Stop Mode Selection
STOPE
ENBDM 1
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
x
Stop3 with voltage regulator active
1
0
Either bit a 0
0
Stop3
1
0
Either bit a 0
1
Stop2