RX230 Group, RX231 Group
Initial Settings and Usage Procedure of RTC Battery Backup Function
R01AN4831EJ0100 Rev.1.00
Page 6 of 23
Aug.20.19
A system flowchart of the sample program is shown below.
Figure 1.2 System Flowchart
Battery backup power
supply voltage drop
(< 1.8 V) detected
VCC on
Initialize LCD
Display RTC information on LCD
VBATRLVDETF == 2?
Initialize sub clock oscillator, RTC
setting and switch count
Clear VBATRLVDETF bit to 0
No
Yes
Check whether battery voltage
has dropped below 1.8V
Vdet1 interrupt
Save data to flash
if VCC drops
below 3.1V
Return
VBATT interrupt
Display voltage drop alert
If VBATT voltage drops
(below 2.2V) detected
Return
