Real-Time Clock

Functions for configuring and using the Real-Time Clock peripheral. More...

Data Structures
union	rtc_date_time_t

Macros
#define	RTC_REFERENCE_YEAR   (2020)

Typedefs
typedef enum rtc_alarm_match_t	rtc_alarm_match_t
typedef void(*	rtc_cb_t) (uint16_t intflag)

Enumerations
enum	rtc_alarm_match_t { ALARM_MATCH_DISABLED = 0 , ALARM_MATCH_SS , ALARM_MATCH_MMSS , ALARM_MATCH_HHMMSS }

Functions
void	rtc_init (void)
	Initializes the RTC.
void	rtc_enable (void)
	Enables the RTC.
bool	rtc_is_enabled (void)
	Checks if the RTC is enabled.
void	rtc_set_date_time (rtc_date_time_t date_time)
	Sets the date and time.
rtc_date_time_t	rtc_get_date_time (void)
	Returns the date and time.
void	rtc_enable_alarm_interrupt (rtc_date_time_t alarm_time, rtc_alarm_match_t mask)
	Enables the alarm interrupt.
void	rtc_disable_alarm_interrupt (void)
	Disables the alarm callback.
void	rtc_configure_callback (rtc_cb_t callback)
	Configures the RTC alarm callback.

Detailed Description

Functions for configuring and using the Real-Time Clock peripheral.

Gossamer supports use of the RTC peripheral in MODE2 (calendar) mode only.

Function Documentation

rtc_configure_callback()

void rtc_configure_callback

(

rtc_cb_t

callback

)

Configures the RTC alarm callback.

Parameters

callback

The function to call when an RTC interrupt occurs. The callback will be passed a bitmask of the interrupt flags, the full contents of the RTC peripheral's INTFLAG register.

rtc_enable_alarm_interrupt()

void rtc_enable_alarm_interrupt	(	rtc_date_time_t	alarm_time,
		rtc_alarm_match_t	mask
	)

Enables the alarm interrupt.

Parameters

alarm_time	The time that you wish to match. The date is currently ignored.
mask	One of the values in rtc_alarm_match_t indicating which values to check.

rtc_get_date_time()

rtc_date_time_t rtc_get_date_time

(

void

)

Returns the date and time.

Returns

A rtc_date_time_t with the current date and time, with a year value from 0-63 representing 2020-2083.

See also

rtc_set_date_time for notes about how the year is stored.

rtc_init()

void rtc_init

(

void

)

Initializes the RTC.

Configures the RTC for 24-hour clock / calendar mode, with a 1 Hz tick derived from the 1024 Hz clock on GCLK3 (for SAM D devices) or OSC32KCTRL's most accurate 1024 Hz output (for SAM L devices).

rtc_is_enabled()

bool rtc_is_enabled

(

void

)

Checks if the RTC is enabled.

Returns

true if the RTC is enabled; false if not.

rtc_set_date_time()

void rtc_set_date_time

(

rtc_date_time_t

date_time

)

Sets the date and time.

Parameters

date_time

The date and time you wish to set, with a year value from 0-63 representing 2020-2083.

Note

The RTC stores the year as six bits representing a value from 0 to 63. It treats this as a year offset from a reference year, which must be a leap year. Since 2020 was a leap year, and it allows useful dates through 2083, it is assumed that apps will use 2020 as the reference year; thus 1 means 2021, 2 means 2022, etc. You will be responsible for handling this offset in your code, if the calendar year is needed for timestamp calculation logic or display purposes.