Freescale Semiconductor MC68HC908MR32 - Manual (Page 190)

System Integration Module (SIM)
MC68HC908MR32 • MC68HC908MR16 Data Sheet, Rev. 6.1
190 Freescale Semiconductor
14.5.1.2 Software Interrupt (SWI) Instruction
The software interrupt (SWI) instruction is a non-maskable instruction that causes an interrupt regardless
of the state of the interrupt mask
(I bit) in the condition code register.
14.5.2 Reset
All reset sources always have equal and highest priority and cannot be arbitrated.
14.6 Low-Power Mode
Executing the WAIT instruction puts the MCU in a low power-consumption mode for standby situations.
The SIM holds the CPU in a non-clocked state. WAIT clears the interrupt mask (I) in the condition code
register, allowing interrupts to occur.
14.6.1 Wait Mode
In wait mode, the CPU clocks are inactive while the peripheral clocks continue to run. Figure 14-11 shows
the timing for wait mode entry.
A module that is active during wait mode can wake up the CPU with an interrupt if the interrupt is enabled.
Stacking for the interrupt begins one cycle after the WAIT instruction during which the interrupt occurred.
Refer to the wait mode subsection of each module to see if the module is active or inactive in wait mode.
Some modules can be programmed to be active in wait mode.
Wait mode can also be exited by a reset. If the COP disable bit, COPD, in the configuration register is
logic 0, then the computer operating properly module (COP) is enabled and remains active in wait mode.
Figure 14-11. Wait Mode Entry Timing
Figure 14-12 and Figure 14-13 show the timing for wait recovery.
Figure 14-12. Wait Recovery from Interrupt
WAIT ADDR + 1 SAME SAME IAB
IDB PREVIOUS DATA NEXT OPCODE SAME
WAIT ADDR
SAME
R/W
Note: Previous data can be operand data or the WAIT opcode, depending on the
last instruction.
$6E0C $6E0B $00FF $00FE $00FD $00FC
$A6 $A6 $01 $0B $6E $A6
IAB
IDB
EXITSTOPWAIT
Note: EXITSTOPWAIT = RST pin OR CPU interrupt