Detailed Description

Real-time clock conversion functions.

The preferred representation for SatCat5 real-time functions is the number of milliseconds since the GPS epoch (i.e., midnight between 1980 Jan 5 and Jan 6). This file defines various conversions to and from this format.

(This is separate from the more precise satcat5::ptp::Time class used for PTP.)

GPS time has the advantage that it has no time-zones, no leap-seconds, etc. By definition, GPS time is always behind TAI by exactly 19 seconds. Because UTC inserts leap seconds every few years, the offset from GPS to UTC varies. From 2017-2025, GPS has lead UTC by 18 seconds.

Conversion functions to human-readable calendar formats are effectively in a GPS "time-zone" that is more-or-less equivalent to TAI/UTC as noted above.

For more information, including the current GPS/TAI/UTC time: http://www.leapsecond.com/java/gpsclock.htm For an online conversion tool: https://www.labsat.co.uk/index.php/en/gps-time-calculator

See also: ptp_time.h

Definition in file datetime.h.

#include <satcat5/io_core.h>
#include <satcat5/polling.h>
#include <satcat5/ptp_time.h>
#include <satcat5/timeref.h>

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Classes
struct	satcat5::datetime::GpsTime
	GPS week-number and time-of-week. More...

struct	satcat5::datetime::RtcTime
	Hardware RTC (e.g., Renesas ISL12082). More...

class	satcat5::datetime::Clock
	Real-time clock for tracking date/time. More...

Functions

satcat5::datetime::GpsTime	satcat5::datetime::to_gps (s64 time)
	Convert an internal timestamp into the designated format. More...

satcat5::ptp::Time	satcat5::datetime::to_ptp (s64 time)
	Convert an internal timestamp into the designated format. More...

satcat5::datetime::RtcTime	satcat5::datetime::to_rtc (s64 time)
	Convert an internal timestamp into the designated format. More...


s64	satcat5::datetime::from_gps (const satcat5::datetime::GpsTime &time)
	Convert the designated format into an internal timestamp. More...

s64	satcat5::datetime::from_ptp (const satcat5::ptp::Time &time)
	Convert the designated format into an internal timestamp. More...

s64	satcat5::datetime::from_rtc (const satcat5::datetime::RtcTime &time)
	Convert the designated format into an internal timestamp. More...

Variables
static constexpr s64	satcat5::datetime::TIME_ERROR = 0
	A date/time of zero indicates an error.

static const datetime::RtcTime	satcat5::datetime::RTC_ERROR = {0, 0, 0, 0, 0, 0, 0, 0, 0}
	Special datetime::RtcTime value indicating an error.

static const u8	satcat5::datetime::RTC_MIL_BIT = 0x80
	Bit-flag in HR field indicating 24-HOUR clock format. More...

satcat5::datetime::Clock	satcat5::datetime::clock
	Global instance of the datetime::Clock class. More...


static constexpr u32	satcat5::datetime::ONE_SECOND = 1000
	Common time-related constants, measured in milliseconds. More...

static constexpr u32	satcat5::datetime::ONE_MINUTE = 60 * ONE_SECOND
	Common time-related constants, measured in milliseconds. More...

static constexpr u32	satcat5::datetime::ONE_HOUR = 60 * ONE_MINUTE
	Common time-related constants, measured in milliseconds. More...

static constexpr u32	satcat5::datetime::ONE_DAY = 24 * ONE_HOUR
	Common time-related constants, measured in milliseconds. More...

static constexpr u32	satcat5::datetime::ONE_WEEK = 7 * ONE_DAY
	Common time-related constants, measured in milliseconds. More...

Function Documentation

◆ from_gps()

s64 satcat5::datetime::from_gps ( const satcat5::datetime::GpsTime & time )

Convert the designated format into an internal timestamp.

Explanation of the SatCat5 datetime format.

Definition at line 191 of file datetime.cc.

◆ from_ptp()

s64 satcat5::datetime::from_ptp ( const satcat5::ptp::Time & time )

Convert the designated format into an internal timestamp.

Explanation of the SatCat5 datetime format.

Definition at line 22 of file datetime.cc.

◆ from_rtc()

s64 satcat5::datetime::from_rtc ( const satcat5::datetime::RtcTime & time )

Convert the designated format into an internal timestamp.

Explanation of the SatCat5 datetime format.

Definition at line 239 of file datetime.cc.

◆ to_gps()

GpsTime satcat5::datetime::to_gps ( s64 time )

Convert an internal timestamp into the designated format.

Explanation of the SatCat5 datetime format.

Definition at line 184 of file datetime.cc.

◆ to_ptp()

ptp::Time satcat5::datetime::to_ptp ( s64 time )

Convert an internal timestamp into the designated format.

Explanation of the SatCat5 datetime format.

Definition at line 26 of file datetime.cc.

◆ to_rtc()

RtcTime satcat5::datetime::to_rtc ( s64 time )

Convert an internal timestamp into the designated format.

Explanation of the SatCat5 datetime format.

Definition at line 195 of file datetime.cc.

Variable Documentation

◆ clock

Clock satcat5::datetime::clock

extern

Global instance of the datetime::Clock class.

This instance is provided for general-use and convenience, but specialized use-cases may create and manage their own clocks.

Definition at line 16 of file datetime.cc.