Low-level RTC (Real Time Clock) peripheral driver. More...

Detailed Description

Low-level RTC (Real Time Clock) peripheral driver.

Note
The values used for setting and getting the time/alarm should conform to the struct tm specification. Compare: http://pubs.opengroup.org/onlinepubs/7908799/xsh/time.h.html

(Low-) Power Implications

After the RTC has been initialized (i.e. after calling rtc_init()), the RTC should be powered on and running. The RTC can then be powered off manually at a later point in time by calling the rtc_poweroff() function. When the RTC is powered back on using the rtc_poweron() function, it should transparently continue its previously configured operation.

On many CPUs, certain power states might need to be blocked in rtc_init(), so that it is ensured that the RTC will function properly while it is enabled.

Files

file  rtc.h
 Low-level RTC peripheral driver interface definitions.
 

Macros

#define RIOT_EPOCH   (2020)
 Earliest year of the RTC. More...
 

Typedefs

typedef void(* rtc_alarm_cb_t) (void *arg)
 Signature for alarm Callback. More...
 

Functions

void rtc_init (void)
 Initialize RTC module.
 
int rtc_set_time (struct tm *time)
 Set RTC to given time. More...
 
int rtc_get_time (struct tm *time)
 Get current RTC time. More...
 
int rtc_set_alarm (struct tm *time, rtc_alarm_cb_t cb, void *arg)
 Set an alarm for RTC to the specified value. More...
 
int rtc_get_alarm (struct tm *time)
 Gets the current alarm setting. More...
 
void rtc_clear_alarm (void)
 Clear any set alarm, do nothing if nothing set.
 
void rtc_poweron (void)
 Turns the RTC hardware module on.
 
void rtc_poweroff (void)
 Turns the RTC hardware module off.
 
void rtc_tm_normalize (struct tm *time)
 Normalize the time struct. More...
 
int rtc_tm_compare (const struct tm *a, const struct tm *b)
 Compare two time structs. More...
 
uint32_t rtc_mktime (struct tm *t)
 Convert time struct into timestamp. More...
 
void rtc_localtime (uint32_t time, struct tm *t)
 Converts an RTC timestamp into a time struct. More...
 
bool rtc_tm_valid (const struct tm *t)
 Verify that a time struct t contains valid data. More...
 

Macro Definition Documentation

◆ RIOT_EPOCH

#define RIOT_EPOCH   (2020)

Earliest year of the RTC.

01.01.$RIOT_EPOCH will be the reset value of the RTC if supported.

Internal RTC helper functions such as

See also
rtc_mktime and
rtc_localtime will not work on dates earlier than that.

Definition at line 58 of file rtc.h.

Typedef Documentation

◆ rtc_alarm_cb_t

typedef void(* rtc_alarm_cb_t) (void *arg)

Signature for alarm Callback.

Parameters
[in]argoptional argument to put the callback in the right context

Definition at line 66 of file rtc.h.

Function Documentation

◆ rtc_get_alarm()

int rtc_get_alarm ( struct tm *  time)

Gets the current alarm setting.

Parameters
[out]timePointer to structure to receive alarm time
Returns
0 for success
-1 an error occurred

◆ rtc_get_time()

int rtc_get_time ( struct tm *  time)

Get current RTC time.

Parameters
[out]timePointer to the struct to write the time to.
Returns
0 for success
-1 an error occurred

◆ rtc_localtime()

void rtc_localtime ( uint32_t  time,
struct tm *  t 
)

Converts an RTC timestamp into a time struct.

Parameters
[in]timeelapsed seconds since RIOT_EPOCH
[out]tthe corresponding timestamp

◆ rtc_mktime()

uint32_t rtc_mktime ( struct tm *  t)

Convert time struct into timestamp.

Precondition
The time structs a and b are assumed to be normalized. Use rtc_tm_normalize to normalize a struct tm that has been manually edited.
Parameters
[in]tThe time struct to convert
Returns
elapsed seconds since RIOT_EPOCH

◆ rtc_set_alarm()

int rtc_set_alarm ( struct tm *  time,
rtc_alarm_cb_t  cb,
void *  arg 
)

Set an alarm for RTC to the specified value.

Note
Any already set alarm will be overwritten.
Parameters
[in]timeThe value to trigger an alarm when hit.
[in]cbCallback executed when alarm is hit.
[in]argArgument passed to callback when alarm is hit.
Returns
0 for success
-2 invalid time parameter
-1 other errors

◆ rtc_set_time()

int rtc_set_time ( struct tm *  time)

Set RTC to given time.

Parameters
[in]timePointer to the struct holding the time to set.
Returns
0 for success
-1 an error occurred

◆ rtc_tm_compare()

int rtc_tm_compare ( const struct tm *  a,
const struct tm *  b 
)

Compare two time structs.

Precondition
The time structs a and b are assumed to be normalized. Use rtc_tm_normalize to normalize a struct tm that has been manually edited.
Parameters
[in]aThe first time struct.
[in]bThe second time struct.
Returns
an integer < 0 if a is earlier than b
an integer > 0 if a is later than b
0 if a and b are equal

◆ rtc_tm_normalize()

void rtc_tm_normalize ( struct tm *  time)

Normalize the time struct.

Note
The function modifies the fields of the tm structure as follows: If structure members are outside their valid interval, they will be normalized. So that, for example, 40 October is changed into 9 November.

If RTC_NORMALIZE_COMPAT is 1 tm_wday and tm_yday are set to values determined from the contents of the other fields.

Parameters
timePointer to the struct to normalize.

◆ rtc_tm_valid()

bool rtc_tm_valid ( const struct tm *  t)

Verify that a time struct t contains valid data.

Note
This function checks whether the fields of the struct t are positive and within the bounds set by rtc_tm_normalize.
Parameters
[in]tThe struct to be checked.
Returns
true when valid, false if not