
Resets and Interrupts
Data Sheet
M68HC11E Family — Rev. 5
108
Resets and Interrupts
MOTOROLA
sequence results in which all I/O pins and functions are also restored to their initial 
states. 
To use the IRQ pin as a means of recovering from stop, the I bit in the CCR must 
be clear (IRQ not masked). The XIRQ pin can be used to wake up the MCU from 
stop regardless of the state of the X bit in the CCR, although the recovery sequence 
depends on the state of the X bit. If X is set to 0 (XIRQ not masked), the MCU starts 
up, beginning with the stacking sequence leading to normal service of the XIRQ 
request. If X is set to 1 (XIRQ masked or inhibited), then processing continues with 
the instruction that immediately follows the STOP instruction, and no XIRQ 
interrupt service is requested or pending. 
Because the oscillator is stopped in stop mode, a restart delay may be imposed to 
allow oscillator stabilization upon leaving stop. If the internal oscillator is being 
used, this delay is required; however, if a stable external oscillator is being used, 
the DLY control bit can be used to bypass this startup delay. The DLY control bit is 
set by reset and can be optionally cleared during initialization. If the DLY equal to 
0 option is used to avoid startup delay on recovery from stop, then reset should not 
be used as the means of recovering from stop, as this causes DLY to be set again 
by reset, imposing the restart delay. This same delay also applies to power-on 
reset, regardless of the state of the DLY control bit, but does not apply to a reset 
while the clocks are running. 
F
Freescale Semiconductor, Inc.
For More Information On This Product,
  Go to: www.freescale.com
n
.