Renesas RX230 User manual

Application Note
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RX230 Group, RX231 Group
Initial Settings and Usage Procedure of RTC Battery Backup Function
Summary
This application note describes the initial settings and usage procedure of the battery backup function
incorporated into RX230 Group and RX231 Group MCUs, utilizing Firmware Integration Technology (FIT)
module APIs.
For details of the specifications of the RX230 Group and RX231 Group, refer to RX230 Group, RX231 Group
User’s Manual: Hardware.
Target Devices
RX230 Group and RX231 Group 64- and 100-pin package products
When using this application note with other Renesas MCUs, careful evaluation is recommended after making
modifications to comply with the alternate MCU.
Related Application Notes
Application notes related to this application note are listed below. Consult them in conjunction with this
application note.
•Firmware Integration Technology User’s Manual (R01AN1833)
•RX Family Adding Firmware Integration Technology Modules to Projects (R01AN1723)
•RX Family Adding Firmware Integration Technology Modules to CS+ Projects (R01AN1826)
•RX Family Board Support Package Module Using Firmware Integration Technology (R01AN1685)
•RX231 Group Renesas Starter Kit Sample Code (e2studio for CC-RX) (R01AN3137)
•RX Family Battery Backup Function Module Firmware Integration Technology (R01AN2796)
•RX Family Flash Module Using Firmware Integration Technology (R01AN2184)
•RX231 Group Renesas Starter Kit User’s Manual (R20UT3027EG)
•Renesas Starter Kit for RX231 CPU Board Schematics (R20UT3026EG)

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Contents
1. Overview .................................................................................................................................4
1.1 About this Application Note .....................................................................................................................4
1.2 Operating Environment ...........................................................................................................................7
2. Hardware.................................................................................................................................9
2.1 Overview of Renesas Starter Kit for RX231 (RSK).................................................................................9
2.2 Pins Used................................................................................................................................................9
2.3 Clock Settings........................................................................................................................................10
2.4 LCD Panel .............................................................................................................................................10
2.5 Hardware Modifications.........................................................................................................................10
2.5.1 VBATT Connection..............................................................................................................................10
2.5.2 RTCIC1 Input.......................................................................................................................................11
3. Software................................................................................................................................12
3.1 FIT Modules...........................................................................................................................................12
3.2 SC Components....................................................................................................................................12
3.3 File Composition....................................................................................................................................12
3.4 Option-Setting Memory Settings ...........................................................................................................12
3.5 Constants ..............................................................................................................................................13
3.6 Variables................................................................................................................................................13
3.7 Functions Used......................................................................................................................................13
3.8 Function Specifications .........................................................................................................................14
3.8.1 main.....................................................................................................................................................14
3.8.2 flash_Init..............................................................................................................................................14
3.8.3 display_time.........................................................................................................................................14
3.8.4 display_info..........................................................................................................................................15
3.8.5 backup_time........................................................................................................................................15
4. Flowcharts.............................................................................................................................16
4.1 main Function: main()............................................................................................................................16
4.2 Erase Data Flash Function: flash_Init ()................................................................................................17
4.3 Display Time Information Function: display_time()...............................................................................17
4.4 Battery Status and Switch Push Count Display Function: display_time().............................................18
4.5 Save Time Information Function: backup_time() ..................................................................................19
5. LCD Display and RTC Input Capture Operation.....................................................................20
5.1 LCD Display...........................................................................................................................................20
5.1.1 Execution During Battery Backup Operation.......................................................................................20
5.1.2 Battery Backup Operation Disruption..................................................................................................21
5.2 RTC Input Capture Operation ...............................................................................................................22

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Revision History............................................................................................................................23

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1. Overview
1.1 About this Application Note
The battery backup function uses a dedicated battery backup power supply (VBATT) to ensure that the
RTC’s clock function continues to operate even if the VCC power supply is interrupted. In the operation
example described below, time information from the RTC is displayed on an LCD panel, allowing
confirmation that the RTC continues to operate when in the battery backup state.
The operating conditions of the sample program are described in (1) to (6) below, and the VCC and VBATT
states are listed in Table 1.1.
Figure 1.1 Battery Backup Function
(1) Power-on (VCC on and VBATT on)
The RTC operates, and time information is displayed on the LCD.
(2) Automatic switch to VBATT at VCC drop (VCC on →off, VBATT on)
When the VCC power supply drops below the monitoring voltage (3.10V), the time information and switch
(connected to P34 pin) press count are stored in the data flash.
When the VCC power supply drops still further and reaches VDETBATT ±0.1 V (typ.), the power supply of
the RTC sub-clock switches automatically to the VBATT power supply. The LCD that displays the time
information goes blank.
(3) VBATT voltage drop detection (VCC off, VBATT on)
During battery backup, RTC operation continues. Dung this period, if battery voltage drops below 1.8V,
RTC operation is not guaranteed and VBATRLVDETF bit set to 1. By checking this bit, we can confirm
whether VBAT voltage dropped below 1.8V.
Also, time information is captured using the RTCIC1 pin (rising-edge input).
(4) VCC recovery (VCC off →on, VBATT on)
When VCC recovers to VDETBATT + ±0.1 V (typ.), use of the VCC power supply resumes.
VBATTSR.VBATRLVDETF is checked. If the value is 1, VBATT is determined to be less than 1.8 V and
the RTC is initialized.
(5) Power supply recovery (VCC on, VBATT on)
If VBATT hasn’t dropped below 1.8V, after VCC recovery, the elapsed time is updated, and the latest time
information is displayed on the LCD.
(6) VBATT pin voltage monitor function (VCC on, VBATT on →off)
When VBATT is less than Vdetvbt (is set to 2.2 V), a VBATT pin voltage drop detection interrupt is
generated and a voltage drop alert is displayed on the LCD.
Sub Clock Circuit
RTC RTC Regulator
VDETBATT
VBATT Voltage Monitor
VBATT Volt. Drop Detection
PORT
P34
Battery
Backup
Function
VCC
VBATT
RTCIC1
Voltage Monitoring 1
Switch
Switch
Vcc
VBATT
(1) (2)
VDETBATT
(3)
VDETBATT
(4) (5) (6)

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Table 1.1 Operating Conditions
VCC/VBATT
State
Voltage
Monitor 0
Reset
(Vdet0)
VBATT Pin
Voltage Drop
Detection
Interrupt
(Vdetvbt)
RTC
Count
Operation
LCD
Display
Data Saved
(RAM, Time
Information)
RTC
Initialization
Input Capture
(1)
(initial state)
Vcc = On (active)
Vbatt = On
No
generated
Enable
Operating
Yes
No
Yes
Enable
(2)
Vcc = OnOff,
Vbatt = On On
(switch to battery)
Generated
No
Operating
Turn off
Saved
No
Enable
(3)
Vcc = Off,
Vbatt = On
(battery active)
On hold
No
Operating
(No if
VBATT
below
1.8V)
No
Saved
No
Enable
(inputted)
(4)
Vcc = Off On,
(switch to VCC)
Vbatt = On
Released
No
Operating
Turn on
Saved
No
(Yes if VBATT
below 1.8V
detected)
Enable
(5)
Vcc = On
(VCC active)
Vbatt = On
Not
generated
Enable
Operating
Yes
Saved
No
Enable
(6)
Vcc = On
Vbatt = On Off
(battery depleted)
Not
generated
Generated
Operating
Yes
Saved
No
Enable

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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

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1.2 Operating Environment
Table 1.2, Operating Environment, shows the environment in which the operation of the sample program was
confirmed. Table 1.2 Operating Environment
Item
Description
MCU used
R5F52318ADFP (RX231 Group)
Board used
Renesas Starter Kit for RX231 (product number: R0K505231S000BE)
CPU operating frequency
Refer to 2.3, Clock Settings.
Integrated development
environment
Renesas Electronics
e2studio Version 7.5.0
C compiler
Renesas Electronics
C/C++ Compiler Package for RX Family V.3.01.00
Emulator
E1
Endian order
Little-endian
The sample program uses FIT modules to control battery backup function and programming of the flash
memory. LCD display software uses the sample code provided with the RSK board, and the drivers of other
functions than battery backup and flash programming are generated using Smart Configurator (SC). Note
that in the sample program, R_Config_RTC_Create function call, which is generated for RTC battery backup
operation by SC, r_cg_hardware_setup.c file is deleted.
void R_Systeminit(void)
{
/* Enable writing to registers related to operating modes, LPC, CGC and
software reset */
SYSTEM.PRCR.WORD = 0xA50FU;
/* Enable writing to MPC pin function control registers */
MPC.PWPR.BIT.B0WI = 0U;
MPC.PWPR.BIT.PFSWE = 1U;
/* Initialize clocks settings */
R_CGC_Create();
/* Set peripheral settings */
R_Config_PORT_Create();
R_Config_CMT0_Create();
R_Config_LVD1_Create();
R_Config_SCI8_Create();
R_Config_RTC_Create(); ←Deleted.
Figure 1.3 Modification of r_cg_hardware_setup.c

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Table 1.3 lists the FIT modules used, Table 1.4 list the sample code provided with RSK board, and Table 1.5
lists the SC components. For details of the LCD display software, refer to RX231 Group: Renesas Starter Kit
Sample Code (e2studio for CC-RX) (R01AN3137EG0200).
Table 1.3 FIT Module
Type
Application Note Title (Document No.)
FIT Module Name
Revision
BSP
RX Family Board Support Package Module Using
Firmware Integration Technology (R01AN1685)
r_bsp_rx
5.20
Device driver
RX Family Battery Backup Function Module Firmware
Integration Technology (R01AN2796)
r_vbatt_rx
1.03
RX Family Flash Module Using Firmware Integration
Technology (R01AN2184)
r_flash_rx
4.00
Table 1.4 Sample Code
Type
Application Note Title (Document No.)
Revision
Sample Code
RX231 Group Renesas Starter Kit Sample Code (e2studio for CC-RX)
(R01AN3137)
2.00
Table 1.5 SC Components
Type
Component Name
Module Name
Revision
Device driver
Realtime clock
RTC
1.30
Compare match timer
CMT0
1.70
Voltage detection circuit
LVD1
1.50
Ports
PORT
1.70
SPI clock synchronous mode
SCI8
1.50

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2. Hardware
2.1 Overview of Renesas Starter Kit for RX231 (RSK)
Excerpted from RSKRX231 manual
CAN
Pmod LCD
Pmod connector Expansion board
interface
(application header) Reset switch
Pmod connector
USB serial
port
Power LED
Power
connector
(5 V)
E1
connector
User LED
USB Host
USB Function
port
User switches
E1 emulator
Potentiometer
Expansion board
interface
(application header)
Touch keys
Touch slider
Figure 2.1 RSKRX231
2.2 Pins Used
The MCU pins used are listed below. Table 2.1 Related Pins
Pin Name
I/O
Description
PC7
Output
SCI8 transmit
PC5
Output
SCI8 clock
P31
Input
RTC input capture (RTCIC1)
P34
Input
Switch input (SW2)
P33
Output
LCD control
PE3
Output
LCD control
PE4
Output
LCD control
PE7
Output
LCD control

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2.3 Clock Settings
Table 2.2, Clock Settings, lists the clocks used by the sample program.
Table 2.2 Clock Settings
Name
Operating
Frequency
Clock
Source
Frequency
Dividing Ratio
Multiplication
Factor
Main clock
8 MHz
Implemented
externally
⎯
⎯
Subclock
32.768 kHz
Implemented
externally
⎯
⎯
High-speed on-chip oscillator (HOCO)
Stopped
⎯
⎯
⎯
Low-speed on-chip oscillator (LOCO)
Stopped
⎯
⎯
⎯
IWDT on-chip oscillator
Stopped
⎯
⎯
⎯
PLL circuit
54 MHz
Main clock
2
13.5
USB clock
48 MHz
Main clock
2
12
System clock (ICLK)
54 MHz
PLL
1
⎯
Peripheral clock A (PCLKA)
54 MHz
PLL
1
⎯
Peripheral clock B (PCLKB)
27 MHz
PLL
2
⎯
Peripheral clock D (PCLKD)
27 MHz
PLL
2
⎯
Flash interface clock (FCLK)
27 MHz
PLL
2
⎯
2.4 LCD Panel
The LCD panel (Pmod specification) included with the RSK is used.
2.5 Hardware Modifications
To confirm the operation of the sample program, modifications were made to the RSK to enable battery
backup operation.
2.5.1 VBATT Connection
The RX231 RSK board is provided with jumper J10 to allow confirming operation of the battery backup
function. However, jumper J10 is not mounted on the board when it is shipped from the factory and VBATT
pin is connected to VCC by resistor R86. It is therefore necessary to make the following modifications.
1. Remove resistor R86.
2. Solder resistor R85 to the board.
3. Solder a pin header (two-pin) to the board in the jumper J10 location.
For reference when performing modifications, see Figure 2.2, Excerpt from RSKRX231 User’s Manual, and
Figure 2.3, VBATT Circuit Detail Excerpted from RSKRX231 CPU Board Schematics.

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Figure 2.2 Excerpt from RSKRX231 User’s Manual
Figure 2.3 VBATT Circuit Detail Excerpted from RSKRX231 CPU Board Schematics
2.5.2 RTCIC1 Input
The RX231 RSK board is designed SW1 for IRQ1 (RTCIC1) input and it is set to “pull-up by VCC.” It is
therefore necessary to make the following modifications.
1. Remove resistor R271.
2. Connect IRQ1 to VBATT battery through an external switch.
3. When the switch is turned on, VBATT is connected to IRQ1.
For reference when performing modifications, see Figure 2.4, RTCIC1 Circuit Detail Excerpted from
RSKRX231 CPU Board Schematics.
GROUND
Figure 2.4 RTCIC1 Circuit Detail Excerpted from RSKRX231 CPU Board Schematics

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3. Software
The configuration and functions of the software referenced in this application note are described below. The
folder containing the files generated automatically by the FIT modules and SC is smc_gen, which is in the src
folder.
3.1 FIT Modules
The folders containing the FIT modules used by the sample program are listed below.
Table 3.1 FIT Module Folders
Folder Name
Module Name
Description
r_bsp
Board support package module
Supplies code for the MCU and the board used.
r_vbat_rx
Battery backup module
Supplies battery backup control functionality.
r_flash_rx
Flash control module
Supplies control functionality and drivers for flash
programming.
r_config
FIT header files
Header files of FIT modules used
Note: For the configuration and functions of the various FIT modules, refer to the specifications of each
module.
3.2 SC Components
The folders containing the SC components used by the sample program are listed below.
Table 3.2 SC Component Folders
Folder Name
Component Name
Description
Config_RTC
Realtime clock module
Supplies control functionality and drivers for the
realtime clock.
Config_CMT0
Compare match timer module
Supplies control functionality and drivers for the
compare match timer.
Config_LVD1
Voltage detection circuit module
Supplies control functionality and drivers for the
voltage detection circuit.
Config_PORT
Port module
Supplies control functionality and drivers for the
port.
Config_SCI8
SPI clock synchronous
communication module
Supplies control functionality and drivers for the
SPI clock synchronous communication.
general
SC header files
Header files of SC components used
Note: For the configuration and functions of the various SC components, refer to the description of each
component in Smart Configurator User’s Manual: RX API Reference (R20UT4360).
3.3 File Composition
The file configuration of the software referenced in this application note is described below.
Files, including components of FIT modules, generated automatically by the integrated development
environment are omitted. Table 3.3 User Files
Folder Name
File Name
Description
Remarks
src
main.c
Main processing source file
Created by user
r_okaya_lcd.c
LCD display software
RSK sample code
ascii.c
ASCII data file for LCD display
RSK sample code
Note: The smc_gen folder in the src folder contains files generated automatically by FIT modules and the
SC environment.
3.4 Option-Setting Memory Settings
Table 3.4, Option-Setting Memory Settings, lists the option-setting memory settings used by the sample
program.

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Table 3.4 Option-Setting Memory Settings
Bit
Symbol
Bit Name
Function
Setting Value
b1, b0
VDSEL[1:0]
Voltage detection 0 level
select bits
2.51 V is selected.
10b
b2
LVDAS
Voltage detection 0 circuit
start bit
Voltage monitoring 0 reset is
enabled after a reset.
0
3.5 Constants
None.
3.6 Variables
Table 3.5, Global Variables, lists the global variables used by the sample program.
Table 3.5 Global Variables
Type
Variable Name
Description
struct
rtc_calendarcounter_value_t
Year/month/day/hour/minute/second structure
uint8_t
batty_err
Battery state
sw_counter
Switch push count
g_rtc_interrupt
RTC interrupt generated indication
3.7 Functions Used
Table 3.6, User Functions, lists the functions referenced in the user file (main.c).
Table 3.6 User Functions
Function Name
Outline
main()
System main function
display_time ()
Display time information.
display_info ()
Display battery and switch states.
backup_time()
Write time information to the data flash.
flash_Init()
Erase the data flash and perform blank checking.
The functions used in the sample code of each FIT/SC modules are listed below.
Table 3.7 SC Module Functions
Function Name
Outline
Contained
in File
R_VBATT_Open ()
Initialize battery backup.
r_vbatt_rx.c
R_VBATT_GetStatus ()
Get battery backup status.
r_vbatt_rx.c
R_Config_RTC_Create ()
Initialize RTC.
Config_RTC.c
R_Config_RTC_Start
Start RTC.
Config_RTC.c
R_Config_RTC_Set_CalendarCounterValue ()
Set RTC information.
Config_RTC.c
R_Config_RTC_Get_CalendarCounterValue ()
Get RTC information.
Config_RTC.c
R_Config_RTC_Get_CalendarTimeCaptureValue1()
Get RTC capture value.
Config_RTC.c
R_Config_LVD1_Start()
Start LVD1.
Config_LVD1.c
R_Config_LVD1_Stop()
Stop LVD1
Config_LVD1.c
R_FLASH_Open()
Initialize flash.
r_flash_rx.c
R_FLASH_Write()
Program flash.
r_flash_rx.c
R_FLASH_Erase()
Erase flash.
r_flash_rx.c
R_FLASH_BlankCheck()
Run flash blank check.
r_flash_rx.c

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3.8 Function Specifications
User setting functions are described below. For information on FIT module functions, refer to the
specifications of the relevant module.
3.8.1 main Table 3.8 main Function
Item
Details
Function Name
main()
Outline
System main function
Declaration
void main(void)
Description
Controls initial module settings and the system overall.
Functions called
display_time ()
display_info ()
flash_Init ()
R_Config_LVD1_Start()
R_LCD_Init()
R_LCD_Display()
R_FLASH_Open()
R_Config_RTC_Create()
R_Config_RTC_Set_CalendarCounterValue()
R_Config_RTC_Start()
R_VBATT_Open()
R_VBATT_GetStatus()
Arguments
⎯
Return value
⎯
3.8.2 flash_Init Table 3.9 flash_Init Function
Item
Details
Function Name
flash_Init ()
Outline
Erases data flash to store RTC information
Declaration
void flash_Init (void)
Description
Erases block 0 of data flash and performs blank checking.
Functions called
R_FLASH_Erase ()
R_FLASH_BlankCheck ()
Arguments
⎯
Return value
⎯
3.8.3 display_time Table 3.10 display_time Function
Item
Details
Function Name
display_time ()
Outline
Display time information function
Declaration
void display_time (uint8_t)
Description
Reads time information from the RTC and displays it on the LCD.
Functions called
R_Config_RTC_Get_CalendarTimeCaptureValue1 ()
R_Config_RTC_Get_CalendarCounterValue ()
R_LCD_Display ()
Arguments
Display start line count
Return value
⎯

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3.8.4 display_info Table 3.11 display_info Function
Item
Details
Function Name
display_info ()
Outline
Display battery/switch state function
Declaration
void display_ info (uint8_t)
Description
Displays the battery and switch states on the LCD.
Functions called
R_LCD_Display ()
Arguments
Display start line count
Return value
⎯
3.8.5 backup_time Table 3.12 backup_time Function
Item
Details
Function Name
backup_time ()
Outline
Save time information function
Declaration
void backup_time (void)
Description
Reads time information from the RTC and stores it in the data flash.
Functions called
R_Config_RTC_Get_CalendarCounterValue ()
R_FLASH_Write ()
R_Config_LVD1_Stop()
Arguments
⎯
Return value
⎯

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4. Flowcharts
Flowcharts of the functions used by the user file described in this application note are shown below.
4.1 main Function: main()
Figure 4.1 is a flowchart of the main processing routine.
Figure 4.1 main Function
main
LCD initial settings
R_LCD_Init()
LCD display at startup
R_LCD_Display()
Time information initial settings
R_Config_RTC_Create()
Flash initial settings
R_FLASH_Open()
batty_err = 2?
Read data saved to flash
Saved to flash?
Reset time information in saved data
R_Config_RTC_Set_CalendarCounterValue()
Display information in saved data
R_LCD_Display()
Start RTC
R_RTC_Start()
Display captured time information
display_time()
PRD interrupt initial settings
Initialize variable
Erase data flash
flash_Init()
Display RTC time information
display_time()
Display battery state and switch push count
display_info()
Check battery state
R_VBATT_GetStatus()
Check switch push count
Yes
No
Yes
No
Start voltage detection circuit
R_Config_LVD1_Start()
Initialize VBATT
R_VBATT_Open()
Is there a save history (55AAh) at
flash memory address 00100008?
Reads data (time information, battery and
switch states) from flash memory addresses
00100000 to 00100007.
Checks whether VBATT has dropped below 1.8 V while VCC was interrupted.
Is the confirmation flag (batty_err) set to 2?
Resets the data (time information, battery and
switch states) read from the flash memory.
Displays the data (time information, battery and
switch states) read from the flash memory.
Clears the switch push count variable (sw_counter).
Checks whether VBATT has dropped below 2.2 V.
Is the VBATT pin voltage monitor flag set to 1?

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4.2 Erase Data Flash Function: flash_Init ()
Figure 4.2 is a flowchart of the function for erasing the data flash.
flash_Init
RETURN
Data flash blank check
R_FLASH_BlankCheck()
Erase data flash
R_FLASH_Erase()
Figure 4.2 Erase Data Flash Function
4.3 Display Time Information Function: display_time()
Figure 4.3 is a flowchart of the function for displaying time information on the LCD.
display_time
RETURN
line_num = 7?
Read RTC capture value
R_Config_RTC_Get_Calendar
TimeCaptureValue1()
Display on LCD
R_LCD_Display()
Convert year, month, and day to ASCII
Yes
No
Read RTC information
R_Config_RTC_Get_CalendarCounterValue()
Convert hour, minute, and second
to ASCII
Display on LCD
R_LCD_Display()
Set AM/PM display data
Convert month and day to ASCII
Figure 4.3 Display Time Information Function

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4.4 Battery Status and Switch Push Count Display Function: display_time()
Figure 4.4 is a flowchart of the function for displaying the battery status and switch push count on the LCD.
display_info
RETURN
batty_err = 1?
Display on LCD
R_LCD_Display()
Yes
No
Convert switch push count to ASCII
Set empty field in array
Set “ALERT” in array
Figure 4.4 Battery Status and Switch Push Count Display Function

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4.5 Save Time Information Function: backup_time()
Figure 4.5 is a flowchart of the function for saving time information to the data flash (Vdet1 interrupt
processing).
Figure 4.5 Save Time Information Function
backup_time
RETURN
Write to data flash
R_FLASH_Write()
Set year, month, day, hour, minute,
and second data in array
Set battery state and switch push count in array
Setflash write history in array
Read RTC information
R_Config_RTC_Get_CalendarCounterValue()
Verify data written to flash
Stop LVD1
R_Config_LVD1_Stop()

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5. LCD Display and RTC Input Capture Operation
5.1 LCD Display
The sample program displays data information on the LCD screen as described as below.
- Time information: year/month/day and hour/minute/second
- VBATT drop alert and switch push count
- RTC input capture time information: month/day and hour/minute/second
- Flash save data: year/month/day, hour/minute/second, VBATT drop alert/switch push count
RX231 Bat backup
Real time
19/05/01
00:10:30
BAT ALERT │SW 00
Capture time
05/01
00:00:00
Previous time
19/04/30
23:59:50
BAT │SW 00
Time information
LCD screen during
normal operation
VBATT drop alert and switch push count
RTC input capture time
Flash save data
Figure 5.1 Display Setting
5.1.1 Execution During Battery Backup Operation
1. After VCC and VBATT are turned on, the LCD displays the time counting every second. The battery
state and the number of times SW2 has been pressed are also displayed.
RX231 Bat backup
Real time
19/04/30
23:59:40
BAT │SW 12
Capture time
Previous time
Figure 5.2 Display During Normal Operation (After power-on reset)
2. When VCC drops, the time information is saved to the data flash, and the power supply switches from
VCC to VBATT. At this point, the LCD goes blank.
3. During battery backup operation, the RTC continue operating and the time information is updated. When
the RTCIC1 input switch (external) is turned on, the time is captured in the RTC.
4. When VCC recovers, the power supply switches from VBATT to VCC, and the time information is again
displayed on the LCD once every second. The RTC input capture time information also is displayed.