mc68hc908lb8 Freescale Semiconductor, Inc, mc68hc908lb8 Datasheet - Page 182

• Manufacturer Part Number: mc68hc908lb8
• Description: M68hc08 Microcontrollers Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

System Integration Module (SIM)
17.6.2 Stop Mode
In stop mode, the SIM counter is reset and the system clocks are disabled. An interrupt request from a
module can cause an exit from stop mode. Stacking for interrupts begins after the selected stop recovery
time has elapsed. Reset also causes an exit from stop mode.
The SIM disables the clock generator module outputs (BUSCLKX2 and BUSCLKX4) in stop mode,
stopping the CPU and peripherals. Stop recovery time is selectable using the SSREC bit in the mask
option register (MOR). If SSREC is set, stop recovery is reduced from the normal delay of 4096
BUSCLKX4 cycles down to 32. This is ideal for applications using canned oscillators that do not require
long startup times from stop mode.
The SIM counter is held in reset from the execution of the STOP instruction until the beginning of stop
recovery. It is then used to time the recovery period.
Figure 17-16
182
shows stop mode recovery time from interrupt or break.
EXITSTOPWAIT
Note: EXITSTOPWAIT = RST pin or CPU interrupt
External crystal applications should use the full stop recovery time by
clearing the SSREC bit.
To minimize stop current, all pins configured as inputs should be driven to
a logic 1 or logic 0.
BUSCLKX4
RST
IDB
IAB
IDB
IAB
$A6
Figure 17-14. Wait Recovery from Internal Reset
$A6
Figure 17-13. Wait Recovery from Interrupt
$6E0B
$A6
$6E0B
$A6
MC68HC908LB8 Data Sheet, Rev. 1
$A6
$A6
CYCLES
$6E0C
32
NOTE
NOTE
$01
Figure 17-15
$00FF
CYCLES
32
$0B
$00FE
$6E
shows stop mode entry timing.
RST VCT H
$00FD
RST VCT L
$00FC
Freescale Semiconductor