Real time clock. More...

#include <cmsis-plus/rtos/os.h>

Inheritance diagram for os::rtos::clock_rtc:

Public Types
Types & Constants
using	duration_t = port::clock::duration_t
	Type of variables holding clock durations.

using	timestamp_t = port::clock::timestamp_t
	Type of variables holding clock time stamps.

using	offset_t = port::clock::offset_t
	Type of variables holding clock offsets.

Public Member Functions
Constructors & Destructor
	clock_rtc ()
	Construct a real time clock object instance.

virtual	~clock_rtc () override
	Destruct the real time clock object instance.

Public Member Functions
virtual void	start (void) override
	Initialise and make the RTC tick.

Public Member Functions
virtual timestamp_t	now (void) override
	Tell the current time adjusted for epoch.

virtual result_t	sleep_until (timestamp_t timestamp) override
	Sleep until an absolute timestamp.

virtual offset_t	offset (void) override
	Get adjustment offset.

virtual offset_t	offset (offset_t value) override
	Set adjustment offset.

void	internal_check_timestamps (void)

Public Member Functions
timestamp_t	steady_now (void)
	Tell the current time since startup.

result_t	sleep_for (duration_t duration)
	Sleep for a relative duration.

result_t	wait_for (duration_t timeout)
	Timed wait for an event.

timestamp_t	update_for_slept_time (duration_t duration)
	Increase the internal count after a deep sleep.

Public Member Functions
const char *	name (void) const
	Get object name.

Static Public Attributes
Types & Constants
static constexpr uint32_t	frequency_hz = 1
	Real time clock frequency in Hz.

Detailed Description

Real time clock.

This clock counts seconds since epoch or startup.

The real time clock should be derived from a battery powered second counting RTC, initialised at startup with the number of seconds since the standard POSIX epoch (January 1st, 1970).

As any usual clock, it might occasionally be adjusted to match a reference clock, so it cannot be a steady clock.

For systems that do not have a hardware RTC, it can be derived from SysTick, but in this case it must be externally initialised with the epoch.

Example

void
func(void)
{
   // Do something
 
   // Get the current seconds counter.
   clock::timestamp_t seconds = rtclock.now();
 
   // Put the current thread to sleep for a given number of seconds.
   rtclock.sleep_for(7);
 
   // Do something else.
}

Definition at line 598 of file os-clocks.h.

Constructor & Destructor Documentation

◆ clock_rtc()

os::rtos::clock_rtc::clock_rtc ( )

Construct a real time clock object instance.

Warning: Cannot be invoked from Interrupt Service Routines.

Definition at line 653 of file os-clocks.cpp.

◆ ~clock_rtc()

os::rtos::clock_rtc::~clock_rtc ( )

overridevirtual

Destruct the real time clock object instance.

Warning: Cannot be invoked from Interrupt Service Routines.

Definition at line 663 of file os-clocks.cpp.

Member Function Documentation

◆ internal_check_timestamps()

void os::rtos::adjustable_clock::internal_check_timestamps ( void )

inherited

◆ name()

const char * os::rtos::internal::object_named::name ( void ) const

inlineinherited

Get object name.

Parameters: None.

Returns: A null terminated string.

All objects return a non-null string; anonymous objects return "-".

Note: Can be invoked from Interrupt Service Routines.

Definition at line 774 of file os-decls.h.

◆ now()

clock::timestamp_t os::rtos::adjustable_clock::now ( void )

overridevirtualinherited

Tell the current time adjusted for epoch.

Parameters: None.

Returns: The clock current timestamp (time units from startup plus the epoch offset).

Note: Can be invoked from Interrupt Service Routines.

Reimplemented from os::rtos::clock.

Definition at line 416 of file os-clocks.cpp.

◆ offset() [1/2]

clock::offset_t os::rtos::adjustable_clock::offset ( offset_t value )

overridevirtualinherited

Set adjustment offset.

Parameters

[in] value Integer representing the offset to epoch (positive).

Returns: Integer value representing the previous offset to epoch.

Warning: Cannot be invoked from Interrupt Service Routines.

Definition at line 481 of file os-clocks.cpp.

◆ offset() [2/2]

clock::offset_t os::rtos::adjustable_clock::offset ( void )

overridevirtualinherited

Get adjustment offset.

Parameters: None.

Returns: Integer value representing the offset to epoch.

Note: Can be invoked from Interrupt Service Routines.

Definition at line 472 of file os-clocks.cpp.

◆ sleep_for()

result_t os::rtos::clock::sleep_for ( duration_t duration )

inherited

Sleep for a relative duration.

Parameters

[in] duration The number of clock units (ticks or seconds) to sleep.

Return values

ETIMEDOUT	The sleep lasted the entire duration.
EPERM	Cannot be invoked from an Interrupt Service Routines.
EINTR	The sleep was interrupted.

Warning: Cannot be invoked from Interrupt Service Routines.

Definition at line 201 of file os-clocks.cpp.

◆ sleep_until()

result_t os::rtos::adjustable_clock::sleep_until ( timestamp_t timestamp )

overridevirtualinherited

Sleep until an absolute timestamp.

Parameters

[in] timestamp The absolute moment in time, in clock units.

Return values

ETIMEDOUT	The sleep lasted the entire duration.
EPERM	Cannot be invoked from an Interrupt Service Routines.
EINTR	The sleep was interrupted.

Warning: Cannot be invoked from Interrupt Service Routines.

Reimplemented from os::rtos::clock.

Definition at line 433 of file os-clocks.cpp.

◆ start()

void os::rtos::clock_rtc::start ( void )

overridevirtual

Initialise and make the RTC tick.

Parameters: None.

Returns: Nothing.

Must be called only once, during inits.

Warning: Cannot be invoked from Interrupt Service Routines.

Implements os::rtos::clock.

Definition at line 677 of file os-clocks.cpp.

◆ steady_now()

clock::timestamp_t os::rtos::clock::steady_now ( void )

inherited

Tell the current time since startup.

Parameters: None.

Returns: The clock current steady timestamp (time units from startup).

Note: Can be invoked from Interrupt Service Routines.

Definition at line 187 of file os-clocks.cpp.

◆ update_for_slept_time()

clock::timestamp_t os::rtos::clock::update_for_slept_time ( duration_t duration )

inherited

Increase the internal count after a deep sleep.

Parameters

duration Number of ticks lost during sleep.

Returns: The clock current steady timestamp (time units from startup).

During deep sleep the interrupts used to count clock ticks are usually disabled and an external RTC is configured to wake-up the device, so a number of clock ticks are lost.

To keep the clocks accurate, it is recommended to sample the external RTC before entering deep sleep and again when the device is back to life, compute the time slept as difference, and use this function to update the internal clock counter.

Definition at line 324 of file os-clocks.cpp.

◆ wait_for()

result_t os::rtos::clock::wait_for ( duration_t timeout )

inherited

Timed wait for an event.

Parameters

[in] timeout The timeout in clock units.

Return values

result::ok	An event occurred before the timeout.
ETIMEDOUT	The wait lasted the entire duration.
EPERM	Cannot be invoked from an Interrupt Service Routines.
EINTR	The sleep was interrupted.

Warning: Cannot be invoked from Interrupt Service Routines.

Definition at line 282 of file os-clocks.cpp.

Member Data Documentation

◆ frequency_hz

constexpr uint32_t os::rtos::clock_rtc::frequency_hz = 1

staticconstexpr

Real time clock frequency in Hz.

Definition at line 610 of file os-clocks.h.

The documentation for this class was generated from the following files:

Public Types

Public Member Functions

Static Public Attributes

Detailed Description

Constructor & Destructor Documentation

◆ clock_rtc()

◆ ~clock_rtc()

Member Function Documentation

◆ internal_check_timestamps()

◆ name()

◆ now()

◆ offset() [1/2]

◆ offset() [2/2]

◆ sleep_for()

◆ sleep_until()

◆ start()

◆ steady_now()

◆ update_for_slept_time()

◆ wait_for()

Member Data Documentation

◆ frequency_hz