NEC PD17062 User Manual
Page 174
174
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PD17062
14.3.2 CE Reset When Clock-Stop (STOP Instruction) Used
Fig. 14-3 shows the reset operation.
When clock-stop is used, the IRES, RES and RESET signals are output at the time the STOP instruction is
executed.
At this time, the RES signal initializes the timer mode selection register of the control registers to 0000B
and sets the timer carry FF set signal to 100 ms.
Since the IRES signal is output continuously while the CE pin is low level, release by timer carry FF is forcibly
halted.
Since the clock itself stops, the device stops operating.
When the CE pin rises to high level, the clock-stop state is released and oscillation begins.
The IRES signal halts release by timer carry FF. When the timer carry FF set pulse rises after the CE pin
rises, the halt state is released and the program starts from address 0.
Since the timer carry FF set pulse is initialized to 100 ms, CE reset is applied 50 ms after the CE pin rises
to high level.
Fig. 14-3 CE Reset Operation When Clock-Stop Used
5 V
0 V
Normal operation
Clock-stop state
X
OUT
V
DD
CE
Timer carry FF
set pulse
IRES
RES
RESET
Reset signal
CE reset
Program starts from address 0.
Clock stop release
Oscillation start
STOP
0000B
Halt state
50 ms