System Integration Module (SIM)
Low-Power Modes
MC68HC908AZ60A — Rev 2.0 Technical Data
MOTOROLA System Integration Module (SIM) 163
9.7.1 Wait Mode
In wait mode, the CPU clocks are inactive while one set of peripheral
clocks continue to run. Figure 9-12 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 or break. A break interrupt
during wait mode sets the SIM break wait bit, BW, in the SIM break
status register (SBSR). 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 9-12. Wait Mode Entry Timing
Figure 9-13. Wait Recovery from Interrupt or Break
WAIT ADDR + 1 SAME SAMEIAB
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 OR break interrupt
