4524_M Datasheet, PDF (249/310 Pages) Renesas Technology Corp – 4-BIT CISC SINGLE-CHIP MICROCOMPUTER 720 FAMILY / 4500 SERIES

4524 Group
APPLICATION
2.9 Power down
2.9.3 Power down function application example
(1) Clock display
A clock which is high-accuracy and low-power dissipation can be set up by using a 32.768 kHz
quartz-crystal oscillator as a sub-clock and executing the POF instruction.
Outline: The power dissipation can be reduced by using the POF instruction.
Specifications: Time is displayed by the LCD and a 32.768 kHz quartz-crystal oscillator. The main
routine is executed by key input.
Figure 2.9.3 shows the software setting example.
Software start
Address 0 in page 0
Initialization of register Z
Yes
P = “1” ?
No
Cold start initial setting
Warm start initiai setting
T5F = “1” ? ^Yes
No
Clock counter + 1
Time display renewed
No
Key input ?
Yes
Main routine initial setting
To main routine
DI
EPOF
POF
Fig. 2.9.3 Software setting example
Rev.2.00 Aug, 06 2004
REJ09B0107-0200Z
2-85