Real Time Counter (RTC)

See Quick start guide for RTC driver.

This is a driver implementation for the XMEGA RTC.

Minimum allowed alarm time

If current time is close to a time unit roll over, there is a risk to miss this when using a value of 0.

A safe use of this can be in an alarm callback.

Modules
	Related Project(s)
	In this section you can find all the projects related to the Real Time Counter (RTC).
	Quick Start Guide(s)
	In this section you can find a list of all Quick Start guides related to the Real Time Counter (RTC).

Macros
#define	CONFIG_RTC_COMPARE_INT_LEVEL
	Configuration symbol for interrupt level to use on alarm. More...
#define	CONFIG_RTC_OVERFLOW_INT_LEVEL
	Configuration symbol for interrupt level to use on overflow. More...
#define	CONFIG_RTC_PRESCALER
	Configuration symbol for prescaler to use. More...

Typedefs
typedef void(*	rtc_callback_t )(uint32_t time)
	Callback definition for alarm callback. More...

Functions
bool	rtc_alarm_has_triggered (void)
	Check if pending alarm have triggered. More...
uint32_t	rtc_get_time (void)
	Get current time. More...
void	rtc_init (void)
	Initialize the RTC. More...
void	rtc_set_alarm (uint32_t time)
	Set alarm time. More...
static void	rtc_set_alarm_relative (uint32_t offset)
	Set alarm relative to current time. More...
void	rtc_set_callback (rtc_callback_t callback)
	Set callback to call on alarm. More...
void	rtc_set_time (uint32_t time)
	Set current time. More...

#define CONFIG_RTC_COMPARE_INT_LEVEL

Configuration symbol for interrupt level to use on alarm.

Possible values:

• RTC_COMPINTLVL_LO_gc
• RTC_COMPINTLVL_MED_gc
• RTC_COMPINTLVL_HI_gc

#define CONFIG_RTC_OVERFLOW_INT_LEVEL

Configuration symbol for interrupt level to use on overflow.

Possible values:

• RTC_OVFINTLVL_LO_gc
• RTC_OVFINTLVL_MED_gc
• RTC_OVFINTLVL_HI_gc

#define CONFIG_RTC_PRESCALER

Configuration symbol for prescaler to use.

Possible values:

• RTC_PRESCALER_DIV1_gc
• RTC_PRESCALER_DIV2_gc
• RTC_PRESCALER_DIV8_gc
• RTC_PRESCALER_DIV16_gc
• RTC_PRESCALER_DIV64_gc
• RTC_PRESCALER_DIV256_gc
• RTC_PRESCALER_DIV1024_gc

Referenced by rtc_init(), and rtc_set_time().

typedef void(* rtc_callback_t)(uint32_t time)

Callback definition for alarm callback.

Parameters

time	The time of the alarm

bool rtc_alarm_has_triggered

(

void

)

Check if pending alarm have triggered.

Return values

true	Alarm have triggered
false	Alarm is pending

Check if pending alarm have triggered.

Return values

true	Alarm has triggered
false	Alarm is pending

uint32_t rtc_get_time

(

void

)

Get current time.

Returns

Current time value

Note

For devices with the errata "RTC Counter value not correctly read after sleep", this can return old values shortly after waking up from sleep.

Without this errata this function can block for up to 1 RTC clock source cycle after waking up from sleep.

Returns

Current time value

void rtc_init

(

void

)

Initialize the RTC.

Start up the RTC and start counting from 0

Note

The RTC clock source used by the RTC module should be set up before calling this function.

Initialize the RTC.

Starts up the 32kHz oscillator in the backup system and initializes the RTC32.

Note

When the backup system is used, the function rtc_vbat_system_check should be called to determine if a re-initialization must be done.

void rtc_set_alarm

(

uint32_t

time

)

Set alarm time.

Will set absolute alarm time that will call the callback specified by rtc_set_callback on completion. Or possibly use rtc_alarm_has_triggered to check for it.

Any pending alarm will be overwritten with this function.

Parameters

time	Absolute time value. See also Minimum allowed alarm time

Precondition

Needs interrupts disabled if used from several contexts

Will set absolute time of the alarm that will call the callback function specified by rtc_set_callback on expiration. Alternatively, you may use rtc_alarm_has_triggered to check if the alarm has expired.

Any pending alarm will be overwritten with this function.

Parameters

time	Absolute time value. See also Minimum allowed alarm time

Precondition

Needs interrupts disabled if used from several contexts

static void rtc_set_alarm_relative ( uint32_t  offset )

inlinestatic

Set alarm relative to current time.

Parameters

offset

Offset to current time. This is minimum value, so the alarm might happen at up to one time unit later. See also Minimum allowed alarm time

Note

For devices with the errata "RTC Counter value not correctly read after sleep", this can be unsafe to do shortly after waking up from sleep.

Without this errata this function can block for up to 1 RTC clock source cycle after waking up from sleep.

References rtc_get_time(), and rtc_set_alarm().

Referenced by classb_rtc_callback(), main(), and oven_classb_init_tests().

void rtc_set_callback

(

rtc_callback_t

callback

)

Set callback to call on alarm.

Parameters

callback

Callback function pointer

void rtc_set_time

(

uint32_t

time

)

Set current time.

Parameters

time	Time value to set