A96G140/A96G148/A96A148 User’s manual
17. Power down operation
219
Sources to exit from STOP mode is hardware reset and interrupts. The hardware reset re-defines all
control registers. When awaking from STOP mode, enough oscillation stabilization time is required to
normal operation. Figure 111 shows the timing diagram.
As shown in the figure 111, when released from STOP mode, the basic interval timer is activated on
wake-up. Therefore, before STOP instruction, a user must set relevant prescale divide ratio to have
long enough time. This guarantees that an oscillator has started and stabilized.
Figure 113. STOP Mode Release Timing by External Interrupt
17.4
Released operation of STOP mode
After STOP mode is released, operation begins according to content of related interrupt register just
before STOP mode starts (refer to figure.112). If the global interrupt Enable Flag (IE.EA)is set to `1`,
the STOP mode is released by a certain interrupt of which interrupt enable flag = `1` and the CPU jumps
to the relevant interrupt service routine. Even if the IE.EA bit is cleared to
‘
0
’
, the STOP mode is released
by the interrupt of which the interrupt enable flag is set to
‘
1
’
.
OSC
CPU Clock
External
Interrupt
Normal Operation
BIT Counter
STOP Operation
Normal Operation
Release
STOP Instruction
Execute
Clear & Start
By Software setting
Before executed STOP instruction, BIT must be set properly
by software to get stabilization.
n
n+1
n+2
n+3
FF
0
1
1
2
FE
0