User's Manual

Table Of Contents
R01UH0823EJ0110 Rev.1.10 Page 259 of 1852
Nov 30, 2020
RX23W Group 12. Battery Backup Function
12.2.2 VBATT Status Register (VBATTSR)
Note: Set the PRCR.PRC3 bit to 1 (write enabled) before rewriting this register.
Note 1. Only 0 can be written after 1 is read.
VBATRLVDETF Flag (Battery Backup Power Voltage Drop Detection Flag)
This flag indicates whether the battery backup power voltage has dropped below 1.8 V.
[Setting condition]
When the battery backup power voltage drops below 1.8 V.
[Clearing condition]
When 0 is written to the VBATRLVDETF flag after the VBATTSR register is read while this flag is 1.
By setting the VBATRLVDETF flag to 0 after reading as 1 and enabling the backup function (by setting
VBATTCR.VBATTDIS to 0) after power-on, whether the battery backup power voltage has dropped while the VCC is
low can be confirmed when the VCC rises again after the VCC drops and the power supply is switched to VBATT pin
supply.
VBTLVDMON Flag (VBATT Pin Voltage Monitor Flag)
This flag indicates whether the VBATT pin voltage is below Vdetvbt.
This flag is enabled when the VBATTCR.VBATTDIS bit is 0 (battery backup function enabled) and the
VBATTCR.VBTLVDEN bit is 1 (VBATT pin voltage drop detection enabled).
Address(es): 0008 C29Eh
b7 b6 b5 b4 b3 b2 b1 b0
——————
VBTLV
DMON
VBATRL
VDETF
Value after reset:
0000001X
x: Undefined
Bit Symbol Bit Name Description R/W
b0 VBATRLVDETF Battery Backup Power
Voltage Drop Detection Flag
0: Battery backup power voltage drop (< 1.8 V) not detected
1: Battery backup power voltage drop (< 1.8 V) detected
R/W*
1
b1 VBTLVDMON VBATT Pin Voltage Monitor
Flag
0: VBATT pin voltage < Vdetvbt
1: VBATT pin voltage Vdetvbt
or VBATT pin voltage drop detection disabled
R
b7 to b2 Reserved These bits are read as 0. The write value should be 0. R/W