RX230 Group, RX231 Group
Initial Settings and Usage Procedure of RTC Battery Backup Function
R01AN4831EJ0100 Rev.1.00
Page 22 of 23
Aug.20.19
5.2 RTC Input Capture Operation
P30~32 pin can be used as peripheral functions such as serial communication, and RTC input capture
function. Setting operation function should be done during MCU is powered by VCC.
Moreover, during VCC powers, all functions multiplexed can be used. However, after power was switched to
VBATT, only RTC input capture function can continue to operate. This means if these pins are set to other
functions that RTC input capture during VCC power, after switching to VBATT, those function cannot
continue to operate, and pin states become Hi-Z. Therefore, in case battery backup function is used and
P30~32 is not used, it is recommended to set them in input mode and connect to VSS via a resistor.
