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PSoC Creator™ Component Datasheet
Real-Time Clock (RTC)
1.80
Features
Multiple alarm options
Multiple overflow options
Daylight Savings Time (DST) option
General Description
The Real-Time Clock (RTC) component provides accurate time and date information for the
system. The time and date are updated every second based on a one pulse per second interrupt
from a 32.768-kHz crystal. Clock accuracy is based on the crystal provided and is typically
20 ppm.
The RTC keeps track of the second, minute, hour, day of the week, day of the month, day of the
year, month, and year. The day of the week is automatically calculated from the day, month, and
year. Daylight savings time may be optionally enabled and supports any start and end date, as
well as a programmable saving time. The start and end dates may be absolute like 24 March or
relative like the second Sunday in May.
The Alarm provides match detection for a second, minute, hour, day of week, day of month, day
of year, month, and year. A mask selects what combination of time and date information will be
used to generate the alarm. The alarm flexibility supports periodic alarms such as every twenty
third minute after the hour, or a single alarm such as 4:52 a.m. on September 28, 2043.
User code stubs are provided for periodic code execution based on each of the primary time
intervals. Timer intervals are provided at one second, one minute, one hour, one day, one week,
one month, and one year.
When to Use an RTC Component
Use the RTC component when the system requires the current time or date. You can also use
the RTC when you do not need the current time and date but you need accurate timing of events
with one-second resolution.
Input/Output Connections
The RTC component does not have input or output connections.
Cypress Semiconductor Corporation • 198 Champion Court • San Jose, CA 95134-1709 • 408-943-2600
Document Number: 001-85033 Rev. **
Revised December 4, 2012
Real-Time Clock (RTC)
®
PSoC Creator™ Component Datasheet
Component Parameters
Drag an RTC component onto your design and double-click it to open the Configure dialog.
The RTC component contains the following options:
Enable Daylight Savings Time functionality
This parameter allows you to choose whether the daylight savings time functionality is enabled in
the RTC component. The default value is cleared (false).
Start of week
The Start of week parameter allows you to choose start day of the week. Options include:
Sunday (default), Monday, Tuesday, Wednesday, Thursday, Friday, and Saturday.
Clock Selection
You should provide a 32.768-kHz clock from an external crystal oscillator. The accuracy of this
component is defined by the accuracy of the connected external clock source. Refer to the Clock
Editor section of the PSoC Creator Help for information about how to connect and configure the
built-in XTAL_32KHZ clock in your design.
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PSoC Creator™ Component Datasheet
Real-Time Clock (RTC)
Application Programming Interface
Application Programming Interface (API) routines allow you to configure the component using
software. The following table lists and describes the interface to each function. The subsequent
sections cover each function in more detail.
By default, PSoC Creator assigns the instance name “RTC_1” to the first instance of a
component in a given design. You can rename it to any unique value that follows the syntactic
rules for identifiers. The instance name becomes the prefix of every global function name,
variable, and constant symbol. For readability, the instance name used in the following table is
“RTC.”
You should disable the component’s interrupts while calling functions that read or modify global
variables.
Refer to the Registers section of this datasheet for more information, as needed.
Function
Description
RTC_Start()
Enables the RTC component
RTC_Stop()
Stops RTC component operation
RTC_EnableInt()
Enables interrupts of RTC component
RTC_DisableInt()
Disables interrupts of the RTC component; time and date stop running
RTC_WriteTime()
Writes time and date values as current time and date
RTC_ReadTime()
Reads the current time and date
RTC_WriteSecond()
Writes Sec software register value
RTC_WriteMinute()
Writes Min software register value
RTC_WriteHour()
Writes Hour software register value
RTC_WriteDayOfMonth()
Writes DayOfMonth software register value
RTC_WriteMonth()
Writes Month software register value
RTC_WriteYear()
Writes Year software register value
RTC_WriteAlarmSecond()
Writes Alarm Sec software register value
RTC_WriteAlarmMinute()
Writes Alarm Min software register value
RTC_WriteAlarmHour()
Writes Alarm Hour software register value
RTC_WriteAlarmDayOfMonth()
Writes Alarm DayOfMonth software register value
RTC_WriteAlarmMonth()
Writes Alarm Month software register value
RTC_WriteAlarmYear()
Writes Alarm Year software register value
RTC_WriteAlarmDayOfWeek()
Writes Alarm DayOfWeek software register value
RTC_WriteAlarmDayOfYear()
Writes Alarm DayOfYear software register value
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Real-Time Clock (RTC)
PSoC Creator™ Component Datasheet
Function
Description
RTC_ReadSecond()
Reads Sec software register value
RTC_ReadMinute()
Reads Min software register value
RTC_ReadHour()
Reads Min software register value
RTC_ReadDayOfMonth()
Reads DayOfMonth software register value
RTC_ReadMonth()
Reads Month software register value
RTC_ReadYear()
Reads Year software register value
RTC_ReadAlarmSecond()
Reads Alarm Sec software register value
RTC_ReadAlarmMinute()
Reads Alarm Min software register value
RTC_ReadAlarmHour()
Reads Alarm Hour software register value
RTC_ReadAlarmDayOfMonth()
Reads Alarm DayOfMonth software register value
RTC_ReadAlarmMonth()
Reads Alarm Month software register value
RTC_ReadAlarmYear()
Reads Alarm Year software register value
RTC_ReadAlarmDayOfWeek()
Reads Alarm DayOfWeek software register value
RTC_ReadAlarmDayOfYear()
Reads Alarm DayOfYear software register value
RTC_WriteAlarmMask()
Writes the Alarm Mask software register with one bit per time/date entry
RTC_WriteIntervalMask()
Configures what interval handlers will be called from the RTC ISR
RTC_ReadStatus()
Reads the Status software register, which has flags for DST (DST), Leap
Year (LY), AM/PM (AM_PM), and Alarm active (AA)
RTC_WriteDSTMode()
Writes the DST Mode software register
RTC_WriteDSTStartHour()
Writes the DST Start Hour software register
RTC_WriteDSTStartDayOfMonth()
Writes the DST Start DayOfMonth software register
RTC_WriteDSTStartMonth()
Writes the DST Start Month software register
RTC_WriteDSTStartDayOfWeek()
Writes the DST Start DayOfWeek software register
RTC_WriteDSTStartWeek()
Writes the DST Start Week software register
RTC_WriteDSTStopHour()
Writes the DST Stop Hour software register
RTC_WriteDSTStopDayOfMonth()
Writes the DST Stop DayOfMonth software register
RTC_WriteDSTStopMonth()
Writes the DST Stop Month software register
RTC_WriteDSTStopDayOfWeek()
Writes the DST Stop DayOfWeek software register
RTC_WriteDSTStopWeek()
Writes the DST Stop Week software register
RTC_WriteDSTOffset()
Writes the DST Offset register
RTC_Init()
Initializes and restores default configuration provided with the customizer
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PSoC Creator™ Component Datasheet
Function
Real-Time Clock (RTC)
Description
RTC_Enable()
Enables the interrupts, one pulse per second, and interrupt generation on
OPPS event
Global Variables
Variable
Description
RTC_initVar
Indicates whether the RTC has been initialized. The variable is initialized to 0 and
set to 1 the first time RTC_Start() is called. This allows the component to restart
without reinitialization after the first call to the RTC_Start() routine.
If reinitialization of the component is required, then the RTC_Init() function can be
called before the RTC_Start() or RTC_Enable() function.
RTC_currentTimeDate
The current time and date values are stored in this variable.
RTC_statusDateTime
This variable has following flags: DST, Leap Year, AM/PM, and Active Alarm
statuses.
RTC_intervalCfgMask
This variable is used to define what interrupt stub should be executed.
RTC_alarmCfgTimeDate
The alarm time and date values are stored in this variable..
RTC_alarmCurStatus
This variable is used to indicate current active alarm: seconds alarm is active,
minutes alarm is active, and so on.
RTC_alarmCfgMask
This variable is used to mask alarm events: mask seconds alarm, mask minutes
alarm, and so on.
RTC_dstModeType
This variable stores DST mode type’s value: ‘0’ – fixed and ‘1’ – relative.
RTC_dstTimeDateStart
The values for the time and date of the DST start.
RTC_dstTimeDateStop
The values for the time and date of the DST stop.
RTC_dstStartStatus
The DST start status.
RTC_dstStopStatus
The DST stop status.
RTC_dstOffsetMin
The DST offset value in minutes.
void RTC_Start(void)
Description:
Enables the RTC component. This function configures the counter, sets up interrupts, does
all required calculation, and starts the counter.
Parameters:
None
Return Value:
None
Side Effects:
Enables the one pulse per second and central time wheel signals to wake up the device
from low-power modes (Sleep and Alternate Active) and leaves them enabled.
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PSoC Creator™ Component Datasheet
void RTC_Stop(void)
Description:
Stops RTC component operation.
Parameters:
None
Return Value:
None
Side Effects:
Leaves the one pulse per second and the central time wheel signals enabled, which wakes
up the device from low-power modes (Sleep and Alternate Active).
void RTC_EnableInt(void)
Description:
Enables interrupts from the RTC component.
Parameters:
None
Return Value:
None
Side Effects:
None
void RTC_DisableInt(void)
Description:
Disables interrupts from the RTC component. Time and date stop running.
Parameters:
None
Return Value:
None
Side Effects:
None
RTC_TIME_DATE* RTC_ReadTime(void)
Description:
Reads the current time and date.
Parameters:
None
Return Value:
Pointer to the RTC_TIME_DATE..
Side Effects:
None
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PSoC Creator™ Component Datasheet
Real-Time Clock (RTC)
void RTC_WriteTime(RTC_TIME_DATE * timeDate)
Description:
Writes the time and date values as current time and date. Only passes the Second, Minute,
Hour, Month, Day of Month, and Year.
Parameters:
timeDate: Pointer to the RTC_TIME_DATE global structure where new values of time and
date are stored
Return Value:
None
Side Effects:
The RTC component’s interrupt should be disabled before calling this function and enabled
afterwards to avoid RTC counter increment in the middle of the time and date writing.
void RTC_WriteSecond(uint8 second)
Description:
Writes the Sec software register value.
Parameters:
second: Seconds value
Return Value:
None
Side Effects:
None
void RTC_WriteMinute(uint8 minute)
Description:
Writes the Min software register value.
Parameters:
minute: Minutes value
Return Value:
None
Side Effects:
None
void RTC_WriteHour(uint8 hour)
Description:
Writes the Hour software register value.
Parameters:
hour: Hours value
Return Value:
None
Side Effects:
None
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PSoC Creator™ Component Datasheet
void RTC_WriteDayOfMonth(uint8 dayOfMonth)
Description:
Writes the DayOfMonth software register value.
Parameters:
dayOfMonth: DayOfMonth value
Return Value:
None
Side Effects:
None
void RTC_WriteMonth(uint8 month)
Description:
Writes the Month software register value.
Parameters:
month: Month value
Return Value:
None
Side Effects:
None
void RTC_WriteYear(uint16 year)
Description:
Writes the Year software register value.
Parameters:
year: Years value
Return Value:
None
Side Effects:
None
void RTC_WriteAlarmSecond(uint8 second)
Description:
Writes the Alarm Sec software register value.
Parameters:
second: Alarm Seconds value
Return Value:
None
Side Effects:
None
void RTC_WriteAlarmMinute(uint8 minute)
Description:
Writes the Alarm Min software register value.
Parameters:
minute: Alarm Minutes value
Return Value:
None
Side Effects:
None
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PSoC Creator™ Component Datasheet
Real-Time Clock (RTC)
void RTC_WriteAlarmHour(uint8 hour)
Description:
Writes the Alarm Hour software register value.
Parameters:
hour: Alarm Hours value
Return Value:
None
Side Effects:
None
void RTC_WriteAlarmDayOfMonth(uint8 dayOfMonth)
Description:
Writes the Alarm DayOfMonth software register value.
Parameters:
dayOfMonth: Alarm Day Of Month value
Return Value:
None
Side Effects:
None
void RTC_WriteAlarmMonth(uint8 month)
Description:
Writes the Alarm Month software register value.
Parameters:
month: Alarm Months value
Return Value:
None
Side Effects:
None
void RTC_WriteAlarmYear(uint16 year)
Description:
Writes the Alarm Year software register value.
Parameters:
year: Alarm Years value
Return Value:
None
Side Effects:
None
void RTC_WriteAlarmDayOfWeek(uint8 dayOfWeek)
Description:
Writes the Alarm DayOfWeek software register value.
Parameters:
dayOfWeek: Alarm Day Of Week value
Return Value:
None
Side Effects:
None
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PSoC Creator™ Component Datasheet
void RTC_WriteAlarmDayOfYear(uint16 dayOfYear)
Description:
Writes the Alarm DayOfYear software register value.
Parameters:
dayOfYear: Alarm Day Of Year value
Return Value:
None
Side Effects:
None
uint8 RTC_ReadSecond(void)
Description:
Reads the Sec software register value.
Parameters:
None
Return Value:
None
Side Effects:
None
uint8 RTC_ReadMinute(void)
Description:
Reads the Min software register value.
Parameters:
None
Return Value:
Returns the current minute’s value.
Side Effects:
None
uint8 RTC_ReadHour(void)
Description:
Reads the Min software register value.
Parameters:
None
Return Value:
Returns the current hour’s value.
Side Effects:
None
uint8 RTC_ReadDayOfMonth(void)
Description:
Reads the DayOfMonth software register value.
Parameters:
None
Return Value:
Returns the current day of month’s value.
Side Effects:
None
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PSoC Creator™ Component Datasheet
Real-Time Clock (RTC)
uint8 RTC_ReadMonth(void)
Description:
This function reads the Month software register value.
Parameters:
None
Return Value:
Returns the current month’s value.
Side Effects:
None
uint16 RTC_ReadYear(void)
Description:
Reads the Year software register value.
Parameters:
None
Return Value:
Returns the current year’s value.
Side Effects:
None
uint8 RTC_ReadAlarmSecond(void)
Description:
Reads the Alarm Sec software register value.
Parameters:
None
Return Value:
Returns the current second’s alarm value.
Side Effects:
None
uint8 RTC_ReadAlarmMinute(void)
Description:
Reads the Alarm Min software register value.
Parameters:
None
Return Value:
Returns the current minute’s alarm value.
Side Effects:
None
uint8 RTC_ReadAlarmHour(void)
Description:
Reads the Alarm Hour software register value.
Parameters:
None
Return Value:
Returns the current hour’s alarm value is returned
Side Effects:
None
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PSoC Creator™ Component Datasheet
uint8 RTC_ReadAlarmDayOfMonth(void)
Description:
Reads the Alarm DayOfMonth software register value.
Parameters:
None
Return Value:
Returns the current day of month’s alarm value.
Side Effects:
None
uint8 RTC_ReadAlarmMonth(void)
Description:
Reads the Alarm Month software register value.
Parameters:
None
Return Value:
Returns the current month’s alarm value.
Side Effects:
None
uint16 RTC_ReadAlarmYear(void)
Description:
Reads the Alarm Year software register value.
Parameters:
None
Return Value:
Returns the current year’s alarm value.
Side Effects:
None
uint8 RTC_ReadAlarmDayOfWeek(void)
Description:
Reads the Alarm DayOfWeek software register value.
Parameters:
None
Return Value:
Returns the current day of week’s alarm value.
Side Effects:
None
uint16 RTC_ReadAlarmDayOfYear(void)
Description:
Reads the Alarm DayOfYear software register value.
Parameters:
None
Return Value:
Returns the current day of year’s alarm value.
Side Effects:
None
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PSoC Creator™ Component Datasheet
Real-Time Clock (RTC)
void RTC_WriteAlarmMask(uint8 mask)
Description:
Writes the Alarm Mask software register with one bit per time/date entry. Alarm true when all
masked time/date values match Alarm values.
Parameters:
mask: Alarm Mask software register value. See the Alarm Mask Register section for more
information about this parameter.
Return Value:
None.
Side Effects:
None.
void RTC_WriteIntervalMask(uint8 mask)
Description:
Configures what interval handlers will be called from the RTC ISR. See the Interrupt Service
Routines section for information about how to use this functionality.
Parameters:
mask: Interval Mask software register value. See the Interval Mask Register section for
more information about this parameter.
Return Value:
None.
Side Effects:
None.
uint8 RTC_ReadStatus(void)
Description:
Reads the Status software register, which has flags for DST (DST), Leap Year (LY), AM/PM
(AM_PM), and Alarm active (AA).
Parameters:
None
Return Value:
Current component's status with the active alarm bit cleared. Refer to the Status Register
section for more information about the return values.
Side Effects:
Alarm active (AA) flag clear after read.
void RTC_WriteDSTMode(uint8 mode)
Description:
Writes the DST Mode software register That enables or disables DST changes and sets the
date mode to fixed date or relative date. Only generated if DST is enabled.
Parameters:
mode: DST Mode software register value
Return Value:
None
Side Effects:
None
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Real-Time Clock (RTC)
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PSoC Creator™ Component Datasheet
void RTC_WriteDSTStartHour(uint8 hour)
Description:
Writes the DST Start Hour software register. Used for absolute date entry. Only generated if
DST is enabled.
Parameters:
hour: DST Start Hour software register value
Return Value:
None
Side Effects:
None
void RTC_WriteDSTStartDayOfMonth(uint8 dayOfMonth)
Description:
Writes the DST Start DayOfMonth software register. Used for absolute date entry. Only
generated if DST is enabled.
Parameters:
dayOfMonth: DST Start DayOfMonth software register value
Return Value:
None
Side Effects:
None
void RTC_WriteDSTStartMonth(uint8 month)
Description:
Writes the DST Start Month software register. Used for absolute date entry. Only generated
if DST is enabled.
Parameters:
month: DST Start Month software register value
Return Value:
None
Side Effects:
None
void RTC_WriteDSTStartDayOfWeek(uint8 dayOfWeek)
Description:
Writes the DST Start DayOfWeek software register. Used for relative date entry. Only
generated if DST is enabled.
Parameters:
dayOfWeek: DST Start DayOfWeek software register value
Return Value:
None
Side Effects:
None
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PSoC Creator™ Component Datasheet
Real-Time Clock (RTC)
void RTC_WriteDSTStartWeek(uint8 week)
Description:
Writes the DST Start Week software register. Used for relative date entry. Only generated if
DST is enabled.
Parameters:
Week: DST Start Week software register value
Return Value:
None
Side Effects:
None
void RTC_WriteDSTStopHour(uint8 hour)
Description:
Writes the DST Stop Hour software register. Used for absolute date entry. Only generated if
DST is enabled.
Parameters:
hour: DST Stop Hour software register value
Return Value:
None
Side Effects:
None
void RTC_WriteDSTStopDayOfMonth(uint8 dayOfMonth)
Description:
Writes the DST Stop DayOfMonth software register. Used for absolute date entry. Only
generated if DST is enabled.
Parameters:
dayOfMonth: DST Stop DayOfMonth software register value
Return Value:
None
Side Effects:
None
void RTC_WriteDSTStopMonth(uint8 month)
Description:
Writes the DST Stop Month software register. Used for absolute date entry. Only generated
if DST is enabled.
Parameters:
month: DST Stop Month software register value
Return Value:
None
Side Effects:
None
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Real-Time Clock (RTC)
PSoC Creator™ Component Datasheet
void RTC_WriteDSTStopDayOfWeek(uint8 dayOfWeek)
Description:
Writes the DST Stop DayOfWeek software register. Used for relative date entry. Only
generated if DST is enabled.
Parameters:
dayOfWeek: DST Stop DayOfWeek software register value
Return Value:
None
Side Effects:
None
void RTC_WriteDSTStopWeek(uint8 week)
Description:
Writes the DST Stop Week software register. Used for relative date entry. Only generated if
DST is enabled.
Parameters:
week: DST Stop Week software register value
Return Value:
None
Side Effects:
None
void RTC_WriteDSTOffset(uint8 offset)
Description:
Writes the DST Offset register. Allows a configurable increment or decrement of time
between 0 and 255 minutes. Increment occurs on DST start and decrement on DST stop.
Only generated if DST is enabled.
Parameters:
offset: DST Offset software register value
Return Value:
None
Side Effects:
None
void RTC_Init (void)
Description:
Initializes or restores the component according to the customizer Configure dialog settings. It
is not necessary to call RTC_Init() because the RTC_Start() API calls this function and is the
preferred method to begin component operation.
Parameters:
None
Return Value:
None
Side Effects:
All registers will be set to values according to the customizer Configure dialog.
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PSoC Creator™ Component Datasheet
Real-Time Clock (RTC)
void RTC_Enable(void)
Description:
Enables the interrupts, one pulse per second, and interrupt generation on OPPS event.
Parameters:
None
Return Value:
None
Side Effects:
Enables the one pulse per second and central time wheel signals to wake up device from the
low-power (Sleep and Alternate Active) modes and leaves them enabled.
Data Structures
RTC_TIME_DATE
This is the data structure that is used to save the current time and date (RTC_currentTimeDate),
and Alarm time and date (RTC_alarmCfgTimeDate).
typedef struct _RTC_TIME_DATE
{
uint8 Sec;
uint8 Min;
uint8 Hour;
uint8 DayOfWeek;
uint8 DayOfMonth;
uint16 DayOfYear;
uint8 Month;
uint16 Year;
} volatile RTC_TIME_DATE;
RTC_DSTIME
This is the data structure that is used to save time and date values for Daylight Savings Time
Start and Stop (RTC_dstTimeDateStart and RTC_dstTimeDateStop).
typedef struct _RTC_DSTIME
{
uint8 Hour;
uint8 DayOfWeek;
uint8 Week;
uint8 DayOfMonth;
uint8 Month;
} volatile RTC_DSTIME;
Constants
There are several constants that define day of week, day in month, and month. When writing
code use the constants defined in the header (.h) file.
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PSoC Creator™ Component Datasheet
Sample Firmware Source Code
Sample Firmware Source Code PSoC Creator provides numerous example projects that include
schematics and example code in the Find Example Project dialog. For component-specific
examples, open the dialog from the Component Catalog or an instance of the component in a
schematic. For general examples, open the dialog from the Start Page or File menu. As needed,
use the Filter Options in the dialog to narrow the list of projects available to select.
Refer to the “Find Example Project” topic in the PSoC Creator Help for more information.
Interrupt Service Routines
The RTC component uses a single interrupt that triggers every second. The interrupt handler
updates the internal date and time structure, and then calls specific functions at appropriate
intervals based on the setting configured with RTC_WriteIntervalMask() function. The following
functions are called if the corresponding bit is set in the Interval Mask Register:
Every Second handler – RTC_EverySecondHandler()
Every Minute handler – RTC_EveryMinuteHandler()
Every Hour handler – RTC_EveryHourHandler()
Every Day handler – RTC_EveryDayHandler()
Every Week handler – RTC_EveryWeekHandler()
Every Month handler – RTC_EveryMonthHandler()
Every Year handler – RTC_EveryYearHandler()
Stub routines for these functions are provided in which you can add your own code. The routine
stubs are generated in the RTC_INT.c file the first time the project is built. Your code must be
added between the provided comment tags as follows:
void RTC_EverySecondHandler( void )
{
/* Place your every second handler code here. */
/* `#START EVERY_SECOND_HANDLER_CODE` */
/* `#END` */
}
All interrupt status bits of the Power Manager Interrupt Status register are cleared in the interrupt
handler. If an interrupt is generated at the same time as a clear, the bit remains set (which
causes another interrupt).
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PSoC Creator™ Component Datasheet
Real-Time Clock (RTC)
Functional Description
Time and date
All time and date registers are as accessible as software variables. The time and date change is
based on an interrupt event from the Counter component. The following variables are provided:
Sec – Seconds: 0 to 59
Min – Minutes: 0 to 59
Hour – Hours (24 format only): 0 to 23
DayOfMonth – Day of month: 1 to 31
DayOfWeek – Day of week: 1 to 7. The number depends on StartOfWeek parameter settings.
If Start of week is set to Sunday then: 1 – Sunday, 2 – Monday…,7 – Saturday
DayOfYear – Day of year: 1 to 366
Month – Month: 1 to 12
Year – Year: 1900 to 2200 (the actual range is 1 to 65536)
The DayOfWeek is calculated using Zeller’s congruence. Zeller’s congruence is a simple
algorithm optimized for integer math that calculates the day of the week based on year, month,
and day of the month. It accounts for leap years and leap centuries.
When you call the RTC_Start() function, an RTC_SetInitValues() function is called and all
required flags and date calculations are executed. This includes all variables that need
calculation:
DayOfWeek
DayOfYear
LY
AM_PM
DST
Alarm Function
The alarm function provides for seconds, minutes, hours, days of the month, days of the week,
month, year, and day of the year. The same variable names are provided for alarm settings. You
can set any or all of these alarm settings and configure which of these settings are used in
tripping the alarm.
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PSoC Creator™ Component Datasheet
Periodic Interrupts
Interrupt stubs (locations for user code in separate functions) are provided that can run every
second, minute, hour, day, week, month, and year. If code is present in the stub it will be run at
the appropriate interval.
Daylight Savings Time
To enable the Daylight Savings Time feature, select the check box on the Configure dialog (see
the Component Parameters section of this datasheet). Daylight Savings Time is implemented as
a set of API update times, dates, and durations. If the current time and date match the start of
DST time and date then the DST flag is set and the time is incremented by the set duration.
The start and stop date of DST can be given as fixed or relative. The relative date converts to the
fixed one and is checked against the current time as if it were an alarm function. An example of a
fixed date is “24 March.” An example of a relative date is “fourth Sunday in May.”
The conversion of a relative date to a fixed date is implemented as a separate function. It is
called at the end of the first hour after the RTC_Start() function is called, and it sets a conversion
flag in the RTC_Start() function itself that indicates the conversion is done. The next conversion
will be in the next year.
The DST variables for start and stop time and date are as follows:
Hour – Hour: 0 to 23 (fixed and relative)
DayOfWeek – Day of week 1 to 7. The number depends on StartOfWeek parameter settings.
If Start of week is set to Sunday then: 1 – Sunday, 2 – Monday, … ,7 – Saturday (relative)
Week – Week in month: 1 to 5 (relative)
DayOfMonth – Day of month: 1 to 31 (fixed)
Month – Month: 1 to 12 (fixed and relative)
Registers
Status Register
The status register is a read-only register that contains various RTC status bits. This value can
be read using the RTC_ReadStatus() function. There are several bit-field masks defined for the
status register. The #defines are available in the generated header file (.h) as follows:
RTC_STATUS_DST – Status of Daylight Saving Time. This bit goes high when the current
time and date match DST time and date and the time is incremented. This bit goes low after
the DST interval and the time is decremented.
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PSoC Creator™ Component Datasheet
Real-Time Clock (RTC)
RTC_STATUS_LY – Status of leap year. This bit goes high when the current year is a leap
year.
RTC_STATUS_AM_PM – Status of current time. This bit is low from midnight to noon and
high from noon to midnight.
RTC_STATUS_AA – Status of alarm active (that is, the alarm bit). This bit is high when
current time and date match alarm time and date. After the status is read this bit goes low.
Alarm Mask Register
The alarm mask register is a write-only register that allows you to control the alarm bit in the
status register. The alarm bit is generated by ORing the masked bit fields within this register.
This register is written with the RTC_WriteAlarmMask() function call. When writing the alarm
mask register you must use the bit-field definitions as defined in the header (.h) file. The
definitions for the alarm mask register are as follows:
RTC_ALARM_SEC_MASK – The second alarm mask allows you to match the alarm second
register with the current second register. The alarm second register is written with the
RTC_WriteAlarmSecond() function call and read with RTC_ReadAlarmSecond().
RTC_ALARM_MIN_MASK – The minute alarm mask allows you to match the alarm minute
register with the current minute register. The alarm minute register is written with the
RTC_WriteAlarmMinute() function call and read with the RTC_ReadAlarmMinute().
RTC_ALARM_HOUR_MASK – The hour alarm mask allows you to match the alarm hour
register with the current hour register. The alarm hour register is written with the
RTC_WriteAlarmHour() function call and read with the RTC_ReadAlarmHour().
RTC_ALARM_DAYOFWEEK_MASK – The day of week alarm mask allows you to match
the alarm day of week register with the current day of week register. The alarm day of week
register is written with the RTC_WriteAlarmDayOfWeek() function call and read with the
RTC_ReadAlarmDayOfWeek().
RTC_ALARM_DAYOFMONTH_MASK – The day of month alarm mask allows you to match
the alarm day of month register with the current day of month register. The alarm day of
month register is written with the RTC_WriteAlarmDayOfMonth() function call and read with
the RTC_ReadAlarmDayOfMonth().
RTC_ALARM_DAYOFYEAR_MASK – The day of year alarm mask allows you to match the
alarm day of year register with the current day of year register. The alarm day of year register
is written with the RTC_WriteAlarmDayOfYear() function call and read with the
RTC_ReadAlarmDayOfYear().
RTC_ALARM_MONTH_MASK – The month alarm mask allows you to match the alarm
month register with the current month register. The alarm month register is written with the
RTC_WriteAlarmMonth() function call and read with the RTC_ReadAlarmMonth().
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Real-Time Clock (RTC)
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PSoC Creator™ Component Datasheet
RTC_ALARM_YEAR_MASK – The year alarm mask allows you to match the alarm year
register with the current year register. The alarm year register is written with the
RTC_WriteAlarmYear() function call and read with the RTC_ReadAlarmYear().
Interval Mask Register
The interval mask register is a write-only register that allows you to control handling of interrupt
stubs of the RTC component. The interrupt stubs are provided for every second, minute, hour,
day, week, month, and year. To enable interrupt stub execution, set the appropriate bit in this
register. This register is written with the RTC_WriteIntervalMask() function call. When writing the
interval mask register, you must use the bit-field definitions as defined in the header (.h) file. The
definitions for the interval mask register are as follows:
RTC_INTERVAL_SEC_MASK – The second interval mask allows handling an interrupt stub
every second.
RTC_INTERVAL_MIN_MASK – The minute interval mask allows handling an interrupt stub
every minute.
RTC_INTERVAL_HOUR_MASK – The hour interval mask allows handling an interrupt stub
every hour.
RTC_INTERVAL_DAY_MASK – The day interval mask allows handling an interrupt stub
every day.
RTC_INTERVAL_WEEK_MASK – The week interval mask allows handling an interrupt stub
every week.
RTC_INTERVAL_MONTH_MASK – The month interval mask allows handling an interrupt
stub every month.
RTC_INTERVAL_YEAR_MASK – The year interval mask allows handling an interrupt stub
every year.
DST Mode Register
The DST mode register is a write-only register that allows you to set the Daylight Savings Time
mode and enable DST operation. This register is written with the RTC_WriteDSTMode() function
call. When writing the DST mode register you must use the bit-field definition as defined in the
header (.h) file. The definitions for the DST mode register are as follows:
RTC_DST_ENABLE – The enable bit controls enabling the daylight savings time
functionality.
RTC_DST_FIXDATE – Defines the fixed format of the times and dates (start and stop) for
daylight savings time functionality. For example, fixed date is 24 March.
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PSoC Creator™ Component Datasheet
Real-Time Clock (RTC)
RTC_DST_RELDATE – Defines the relative format of the times and dates (start and stop) for
daylight savings time functionality. For example, relative date is second Sunday in May.
Conditional Compilation Information
The RTC API requires one conditional compile definition to handle daylight savings time
functionality. The DST functions are conditionally compiled only if this option is enabled in the
Configure dialog. The software should never use this parameter directly. Instead, use the
symbolic name defined.
RTC_DST_FUNC_ENABLE – The daylight savings time functionality enable define is
assigned to be equal to the DstEnable value (from the Configure dialog) at build time. It is
used throughout the API to compile data saving time functions.
MISRA Compliance
This section describes the MISRA-C:2004 compliance and deviations for the component. There
are two types of deviations defined:
project deviations – deviations that are applicable for all PSoC Creator components
specific deviations – deviations that are applicable only for this component
This section provides information on component-specific deviations. Project deviations are
described in the MISRA Compliance section of the System Reference Guide along with
information on the MISRA compliance verification environment.
The RTC component has not been verified for MISRA-C:2004 coding guidelines compliance.
Resources
The RTC component uses the one-pulse-per-second Interrupt from Power Management.
API Memory Usage
The component memory usage varies significantly, depending on the compiler, device, number
of APIs used and component configuration. The following table provides the memory usage for
all APIs available in the given component configuration.
The measurements have been done with the associated compiler configured in Release mode
with optimization set for Size. For a specific design the map file generated by the compiler can
be analyzed to determine the memory usage.
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Real-Time Clock (RTC)
PSoC Creator™ Component Datasheet
PSoC 3 (Keil_PK51)
Configuration
Default
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PSoC 5 (GCC)
PSoC 5LP (GCC)
Flash
SRAM
Flash
SRAM
Flash
SRAM
Bytes
Bytes
Bytes
Bytes
Bytes
Bytes
2738
25
2264
29
2264
29
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PSoC Creator™ Component Datasheet
Real-Time Clock (RTC)
Component Changes
This section lists the major changes in the component from the previous version.
Version
1.80
Description of Changes
Updated internal Interrupt component.
Added MISRA Compliance section.
1.70
Reason for Changes / Impact
The component was not verified for MISRA
compliance.
Added PSoC 5LP device support.
Added all RTC APIs with CYREENTRANT
keyword when they included in .cyre file.
Not all APIs are truly reentrant. Comments in the
component API source files indicate which
functions are candidates.
This change is required to eliminate compiler
warnings for functions that are not reentrant used
in a safe way: protected from concurrent calls by
flags or Critical Sections.
Minor datasheet edits.
Improve readability.
1.60.a
Updated the description of the
RTC_WriteIntervalMask() function. Updated the
“Interrupt Service Routines” section to make it
clear how interval handlers are configured.
Interrupt handlers usage description update.
1.60
Fixed issues when global variables used in both
code and ISR could potentially be optimized out
by compiler.
Prevents optimization issues that could lead to
unexpected result.
The merger region was added to ISR (RTC_INT.c
file).
Gives more flexibility to RTC component.
Updated the code comments for clarification.
Fixed a few typos.
Gives correct information on component
operation.
Minor datasheet edits and updates
1.50.a
The RTC version 1.50 requires cy_boot version
2.x to be used.
The cy_boot component should be updated up to
version 2.x for RTC version 1.50 could be used.
The “Sample Firmware Source Code” section was
updated to note that datasheet example project
has been added.
The datasheet example project was added to the
PSoC Creator.
RTC_Enable() function description was added.
Every function that is exposed to user should be
described in the datasheet.
Added reference for the parameter descriptions of
the following functions: RTC_WriteAlarmMask(),
RTC_WriteIntervalMask(), and
RTC_ReadStatus().
Clarification comments on the functions’ usage.
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Real-Time Clock (RTC)
Version
1.80
PSoC Creator™ Component Datasheet
Description of Changes
Updated internal Interrupt component.
Added MISRA Compliance section.
1.50
Reason for Changes / Impact
The component was not verified for MISRA
compliance.
Added Keil reentrancy support in version 1.50.
PSoC 3 with the Keil compiler supports the
capability for functions to be called from multiple
flows of control.
Changed the API flow - added the RTC_Init()
function.
To comply with corporate standard and provide an
API to initialize or restore the component without
starting it.
Renamed some global variables to comply with
coding standard. Updated function headers to
describe function global parameters usage and
returns.
Comply with coding rules. No impacts - macros
were created for backward compatibility.
Updated the datasheet.
Added "Component Changes" section. Added
empty "Side Effects" section to the "Application
Programming Interface" section.
The RTCIsLeapYear(uint16 year) function was
replaced by RTC_LEAP_YEAR macros. The
Fixed a bad practice to call functions within ISR,
they were moved out or replaced by macros. Oneline functions should be replaced by macros. The
code, which is used in a few places, should be
replaced by macros.
RTC_SET_ALARM and RTC_IS_BIT_SET were
created. The RTC_IS_BIT_SET macro used in a
few more conditional expressions.
© Cypress Semiconductor Corporation, 2012. The information contained herein is subject to change without notice. Cypress Semiconductor Corporation assumes no responsibility for the use of
any circuitry other than circuitry embodied in a Cypress product. Nor does it convey or imply any license under patent or other rights. Cypress products are not warranted nor intended to be used
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Cypress does not assume any liability arising out of the application or use of any product or circuit described herein. Cypress does not authorize its products for use as critical components in lifesupport systems where a malfunction or failure may reasonably be expected to result in significant injury to the user. The inclusion of Cypress’ product in a life-support systems application
implies that the manufacturer assumes all risk of such use and in doing so indemnifies Cypress against all charges.
Use may be limited by and subject to the applicable Cypress software license agreement.
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