RTCDRV
EMDRV

Detailed Description

Real-time Clock Driver.

The rtcdriver.c and rtcdriver.h source files for the RTCDRV device driver library are in the emdrv/rtcdrv folder.


Introduction

The RTCDRV driver uses the RTC peripheral of a device in Silicon Laboratories Gecko microcontroller family to provide a user-configurable number of software millisecond timers. Oneshot timers and periodic timers are supported. Timers will, when their timeout period has expired, call a user-supplied callback function.

Note
The callback function is called from within an interrupt handler with interrupts disabled.

In addition to the timers, RTCDRV also offers an optional wallclock functionality. The wallclock keeps track of the number of seconds elapsed since RTCDRV initialization.

RTCDRV resolution is 1 ms with 244 us accuracy. On the EFM32G family (classic Gecko), the accuracy is 61 us. Since RTCDRV is interrupt-driven using the default RTC interrupt priority level, timeout accuracy will be affected by the interrupt latency of the system.


Configuration Options

Some properties of the RTCDRV driver are compile-time configurable. These properties are stored in the rtcdrv_config.h file. A template for this file, containing default values, is in the emdrv/config folder. Currently the configuration options are as follows:

  • The number of timers that RTCDRV provides.
  • Inclusion of the wallclock functionality.
  • Integration with the SLEEP driver.

When the integration with the SLEEP driver is enabled, RTCDRV will notify the SLEEP driver which energy mode can be safely used.

To configure RTCDRV, provide a custom configuration file. This is an example rtcdrv_config.h file:

#ifndef SILICON_LABS_RTCDRV_CONFIG_H
#define SILICON_LABS_RTCDRV_CONFIG_H
// Define how many timers RTCDRV provides.
#define EMDRV_RTCDRV_NUM_TIMERS (4)
// Uncomment the following line to include the wallclock functionality.
//#define EMDRV_RTCDRV_WALLCLOCK_CONFIG
// Uncomment the following line to enable integration with the SLEEP driver.
//#define EMDRV_RTCDRV_SLEEPDRV_INTEGRATION
// Uncomment the following line to let the RTCDRV clock on LFRCO or PLFRCO.
// The default is LFXO.
//#define EMDRV_RTCDRV_USE_LFRCO
//#define EMDRV_RTCDRV_USE_PLFRCO
#endif


The API

This section contains brief descriptions of the API functions. For more information about input and output parameters and return values, click on the hyperlinked function names. Most functions return an error code, ECODE_EMDRV_RTCDRV_OK is returned on success, see ecode.h and rtcdriver.h for other error codes.

The application code must include the rtcdriver.h header file.

All API functions can be called from within interrupt handlers.

RTCDRV_Init() , RTCDRV_DeInit()
These functions initialize or deinitialize the RTCDRV driver. Typically, RTCDRV_Init() is called once in the startup code.

RTCDRV_StartTimer() , RTCDRV_StopTimer()
Start/Stop a timer. When a timer expires, a user-supplied callback function is called. A pointer to this function is passed to RTCDRV_StartTimer(). See TimerCallback for details of the callback prototype. Note that it is legal to start an already started timer, which is restarted with the new timeout value.

RTCDRV_AllocateTimer() , RTCDRV_FreeTimer()
Reserve/release a timer. Many functions in the API require a timer ID as an input parameter. Use RTCDRV_AllocateTimer() to aquire this reference.

RTCDRV_TimeRemaining()
Get time left to the timer expiration.

RTCDRV_Delay()
Millisecond delay function. This is an "active wait" delay function.

RTCDRV_IsRunning()
Check if a timer is running.

RTCDRV_GetWallClock() , RTCDRV_SetWallClock()
Get or set wallclock time.

RTCDRV_GetWallClockTicks32() , RTCDRV_GetWallClockTicks64()
Get wallclock time expressed as number of RTC/RTCC counter ticks, available both as 32bit and 64 bit values.

RTCDRV_MsecsToTicks() , RTCDRV_SecsToTicks() , RTCDRV_TicksToMsec() , RTCDRV_TicksToSec()
Conversion functions between seconds, milliseconds, and RTC/RTCC counter ticks.


The timer expiry callback function:
The callback function, prototyped as RTCDRV_Callback_t() , is called from within the RTC peripheral interrupt handler on timer expiration. RTCDRV_Callback_t( RTCDRV_TimerID_t id ) is called with the timer ID as an input parameter.


The timer type:
Timers are either oneshot or periodic.

  • Oneshot timers run only once toward their expiration.
  • Periodic timers will be automatically restarted when they expire.

The timer type is an enumeration, see RTCDRV_TimerType_t for details.


Example

#include " rtcdriver.h "
#include <stddef.h>
int i = 0;
RTCDRV_TimerID_t id;
void myCallback( RTCDRV_TimerID_t id , void * user )
{
(void) user; // unused argument in this example
i++;
if ( i < 10 ) {
// Restart timer
RTCDRV_StartTimer ( id , rtcdrvTimerTypeOneshot , 100, myCallback, NULL );
}
}
int main( void )
{
// Initialization of the RTCDRV driver.
RTCDRV_Init ();
// Reserve a timer.
RTCDRV_AllocateTimer ( & id );
// Start a oneshot timer with 100 millisecond timeout.
RTCDRV_StartTimer ( id , rtcdrvTimerTypeOneshot , 100, myCallback, NULL );
return 0;
}

Macros

#define ECODE_EMDRV_RTCDRV_ALL_TIMERS_USED ( ECODE_EMDRV_RTCDRV_BASE | 0x00000001)
No timers available.
#define ECODE_EMDRV_RTCDRV_ILLEGAL_TIMER_ID ( ECODE_EMDRV_RTCDRV_BASE | 0x00000002)
An illegal timer ID.
#define ECODE_EMDRV_RTCDRV_NOT_INITIALIZED ( ECODE_EMDRV_RTCDRV_BASE | 0x00000006)
The driver is not initialized.
#define ECODE_EMDRV_RTCDRV_OK ( ECODE_OK )
A successful return value.
#define ECODE_EMDRV_RTCDRV_PARAM_ERROR ( ECODE_EMDRV_RTCDRV_BASE | 0x00000004)
An illegal input parameter.
#define ECODE_EMDRV_RTCDRV_TIMER_NOT_ALLOCATED ( ECODE_EMDRV_RTCDRV_BASE | 0x00000003)
A timer is not allocated.
#define ECODE_EMDRV_RTCDRV_TIMER_NOT_RUNNING ( ECODE_EMDRV_RTCDRV_BASE | 0x00000005)
A timer is not running.

Typedefs

typedef void(* RTCDRV_Callback_t ) ( RTCDRV_TimerID_t id, void *user)
Typedef for the user supplied callback function which is called when a timer elapses.
typedef uint32_t RTCDRV_TimerID_t
Timer ID.

Enumerations

enum RTCDRV_TimerType_t {
rtcdrvTimerTypeOneshot = 0,
rtcdrvTimerTypePeriodic = 1
}
Timer type enumerator.

Functions

Ecode_t RTCDRV_AllocateTimer ( RTCDRV_TimerID_t *id)
Allocate timer.
Ecode_t RTCDRV_DeInit (void)
Deinitialize the RTCDRV driver.
Ecode_t RTCDRV_Delay (uint32_t ms)
Millisecond delay function.
Ecode_t RTCDRV_FreeTimer ( RTCDRV_TimerID_t id)
Free timer.
uint32_t RTCDRV_GetWallClock (void)
Get wallclock time.
uint32_t RTCDRV_GetWallClockTicks32 (void)
Get wallclock tick count as a 32bit value. At 4 ticks per millisecond, overflow occurs after approximately 12.5 days.
uint64_t RTCDRV_GetWallClockTicks64 (void)
Get a wallclock tick count as a 64 bit value.
Ecode_t RTCDRV_Init (void)
Initialize the RTCDRV driver.
Ecode_t RTCDRV_IsRunning ( RTCDRV_TimerID_t id, bool *isRunning)
Check if a given timer is running.
uint64_t RTCDRV_MsecsToTicks (uint32_t ms)
Convert from milliseconds to RTC/RTCC ticks.
uint64_t RTCDRV_SecsToTicks (uint32_t secs)
Convert from seconds to RTC/RTCC ticks.
Ecode_t RTCDRV_SetWallClock (uint32_t secs)
Set wallclock time.
Ecode_t RTCDRV_StartTimer ( RTCDRV_TimerID_t id, RTCDRV_TimerType_t type, uint32_t timeout, RTCDRV_Callback_t callback, void *user)
Start a timer.
Ecode_t RTCDRV_StopTimer ( RTCDRV_TimerID_t id)
Stop a given timer.
uint32_t RTCDRV_TicksToMsec (uint64_t ticks)
Convert from RTC/RTCC ticks to milliseconds.
uint64_t RTCDRV_TicksToMsec64 (uint64_t ticks)
Convert from RTC/RTCC ticks to milliseconds with 64-bit resolution.
uint32_t RTCDRV_TicksToSec (uint64_t ticks)
Convert from RTC/RTCC ticks to seconds.
Ecode_t RTCDRV_TimeRemaining ( RTCDRV_TimerID_t id, uint32_t *timeRemaining)
Get time left before a given timer expires.

Typedef Documentation

typedef void(* RTCDRV_Callback_t) ( RTCDRV_TimerID_t id, void *user)

Typedef for the user supplied callback function which is called when a timer elapses.

Note
This callback is called from within an interrupt handler with interrupts disabled.
Parameters
[in] id The timer ID.
[in] user An extra parameter for the user application.

Definition at line 83 of file rtcdriver.h .

Enumeration Type Documentation

enum RTCDRV_TimerType_t

Timer type enumerator.

Enumerator
rtcdrvTimerTypeOneshot

Oneshot timer.

rtcdrvTimerTypePeriodic

Periodic timer.

Definition at line 86 of file rtcdriver.h .

Function Documentation

Ecode_t RTCDRV_AllocateTimer ( RTCDRV_TimerID_t * id )

Allocate timer.

Reserve a timer instance.

Parameters
[out] id The ID of the reserved timer.
Returns
ECODE_EMDRV_RTCDRV_OK on success.
ECODE_EMDRV_RTCDRV_ALL_TIMERS_USED when no timers are available.
ECODE_EMDRV_RTCDRV_PARAM_ERROR if an invalid ID pointer was supplied.
ECODE_EMDRV_RTCDRV_NOT_INITIALIZED if the driver is not initialized.

Definition at line 253 of file rtcdriver.c .

References CORE_DECLARE_IRQ_STATE , CORE_ENTER_ATOMIC , CORE_EXIT_ATOMIC , ECODE_EMDRV_RTCDRV_ALL_TIMERS_USED , ECODE_EMDRV_RTCDRV_NOT_INITIALIZED , ECODE_EMDRV_RTCDRV_OK , and ECODE_EMDRV_RTCDRV_PARAM_ERROR .

Ecode_t RTCDRV_DeInit ( void )

Deinitialize the RTCDRV driver.

Will disable interrupts and turn off the clock to the underlying hardware timer. If the integration with the SLEEP module is enabled, it will remove any restrictions that are set on energy mode usage.

Returns
ECODE_EMDRV_RTCDRV_OK .

Definition at line 463 of file rtcdriver.c .

References CMU_ClockEnable() , cmuClock_RTCC , ECODE_EMDRV_RTCDRV_OK , RTCC_Enable() , SLEEP_SleepBlockEnd() , and sleepEM3 .

Ecode_t RTCDRV_Delay ( uint32_t ms )

Millisecond delay function.

Parameters
[in] ms Milliseconds to stay in the delay function.
Returns
ECODE_EMDRV_RTCDRV_OK on success.
ECODE_EMDRV_RTCDRV_NOT_INITIALIZED if the driver is not initialized.

Definition at line 298 of file rtcdriver.c .

References ECODE_EMDRV_RTCDRV_NOT_INITIALIZED , and ECODE_EMDRV_RTCDRV_OK .

Ecode_t RTCDRV_FreeTimer ( RTCDRV_TimerID_t id )

Free timer.

Release a reserved timer.

Parameters
[out] id The ID of the timer to release.
Returns
ECODE_EMDRV_RTCDRV_OK on success.
ECODE_EMDRV_RTCDRV_ILLEGAL_TIMER_ID if the ID has an illegal value.

Definition at line 331 of file rtcdriver.c .

References CORE_ATOMIC_SECTION , ECODE_EMDRV_RTCDRV_ILLEGAL_TIMER_ID , and ECODE_EMDRV_RTCDRV_OK .

uint32_t RTCDRV_GetWallClock ( void )

Get wallclock time.

Returns
Seconds elapsed since RTCDRV was initialized.

Definition at line 828 of file rtcdriver.c .

References RTCDRV_GetWallClockTicks32() .

uint32_t RTCDRV_GetWallClockTicks32 ( void )

Get wallclock tick count as a 32bit value. At 4 ticks per millisecond, overflow occurs after approximately 12.5 days.

The return value of this function is in counter ticks. Use RTCDRV_TicksToMsec() or RTCDRV_TicksToSec() to convert ticks to the desired time unit.

Returns
A wallclock tick counter.

Definition at line 849 of file rtcdriver.c .

References CORE_DECLARE_IRQ_STATE , CORE_ENTER_ATOMIC , and CORE_EXIT_ATOMIC .

Referenced by RTCDRV_GetWallClock() , and RTCDRV_SetWallClock() .

uint64_t RTCDRV_GetWallClockTicks64 ( void )

Get a wallclock tick count as a 64 bit value.

The return value of this function is in counter ticks. Use RTCDRV_TicksToMsec64() or RTCDRV_TicksToSec() to convert ticks to the desired time unit.

Returns
A wallclock tick counter.

Definition at line 884 of file rtcdriver.c .

References CORE_DECLARE_IRQ_STATE , CORE_ENTER_ATOMIC , and CORE_EXIT_ATOMIC .

Ecode_t RTCDRV_Init ( void )

Initialize the RTCDRV driver.

Will enable all necessary clocks. Initializes internal data structures and configures the underlying hardware timer.

Returns
ECODE_EMDRV_RTCDRV_OK .

Definition at line 357 of file rtcdriver.c .

References CMU_ClockDivSet() , CMU_ClockEnable() , CMU_ClockSelectSet() , CMU_DivToLog2() , cmuClock_LFA , cmuClock_LFE , cmuClock_RTCC , ECODE_EMDRV_RTCDRV_OK , RTCC_Init_TypeDef::presc , RTCC_ChannelInit() , RTCC_Init() , SLEEP_SleepBlockBegin() , and sleepEM3 .

Ecode_t RTCDRV_IsRunning ( RTCDRV_TimerID_t id,
bool * isRunning
)

Check if a given timer is running.

Parameters
[in] id The ID of the timer to query.
[out] isRunning True if the timer is running. False if not running. Only valid if return status is ECODE_EMDRV_RTCDRV_OK.
Returns
ECODE_EMDRV_RTCDRV_OK on success.
ECODE_EMDRV_RTCDRV_ILLEGAL_TIMER_ID if the ID has an illegal value.
ECODE_EMDRV_RTCDRV_TIMER_NOT_ALLOCATED if the timer is not reserved.
ECODE_EMDRV_RTCDRV_PARAM_ERROR if an invalid isRunning pointer was supplied.
ECODE_EMDRV_RTCDRV_NOT_INITIALIZED if the driver is not initialized.

Definition at line 515 of file rtcdriver.c .

References CORE_DECLARE_IRQ_STATE , CORE_ENTER_ATOMIC , CORE_EXIT_ATOMIC , ECODE_EMDRV_RTCDRV_ILLEGAL_TIMER_ID , ECODE_EMDRV_RTCDRV_NOT_INITIALIZED , ECODE_EMDRV_RTCDRV_OK , ECODE_EMDRV_RTCDRV_PARAM_ERROR , and ECODE_EMDRV_RTCDRV_TIMER_NOT_ALLOCATED .

uint64_t RTCDRV_MsecsToTicks ( uint32_t ms )

Convert from milliseconds to RTC/RTCC ticks.

Parameters
[in] ms Millisecond value to convert.
Returns
A number of ticks.

Definition at line 929 of file rtcdriver.c .

uint64_t RTCDRV_SecsToTicks ( uint32_t secs )

Convert from seconds to RTC/RTCC ticks.

Parameters
[in] secs Second value to convert.
Returns
A number of ticks.

Definition at line 945 of file rtcdriver.c .

Ecode_t RTCDRV_SetWallClock ( uint32_t secs )

Set wallclock time.

Parameters
[in] secs A value to set (seconds).
Returns
ECODE_EMDRV_RTCDRV_OK

Definition at line 912 of file rtcdriver.c .

References ECODE_EMDRV_RTCDRV_OK , and RTCDRV_GetWallClockTicks32() .

Ecode_t RTCDRV_StartTimer ( RTCDRV_TimerID_t id,
RTCDRV_TimerType_t type,
uint32_t timeout,
RTCDRV_Callback_t callback,
void * user
)

Start a timer.

Note
It is legal to start an already running timer.
Parameters
[in] id The ID of the timer to start.
[in] type Timer type, oneshot or periodic. See RTCDRV_TimerType_t .
[in] timeout Timeout expressed in milliseconds. If the timeout value is 0, the callback function is called immediately and the timer will not be started.
[in] callback Function to call when the timer expires. See RTCDRV_Callback_t . NULL is a legal value.
[in] user Extra callback function parameter for the user application.
Returns
ECODE_EMDRV_RTCDRV_OK on success.
ECODE_EMDRV_RTCDRV_ILLEGAL_TIMER_ID if the ID has an illegal value.
ECODE_EMDRV_RTCDRV_TIMER_NOT_ALLOCATED if the timer is not reserved.
ECODE_EMDRV_RTCDRV_NOT_INITIALIZED if the driver is not initialized.

Definition at line 568 of file rtcdriver.c .

References CORE_DECLARE_IRQ_STATE , CORE_ENTER_ATOMIC , CORE_EXIT_ATOMIC , ECODE_EMDRV_RTCDRV_ILLEGAL_TIMER_ID , ECODE_EMDRV_RTCDRV_NOT_INITIALIZED , ECODE_EMDRV_RTCDRV_OK , ECODE_EMDRV_RTCDRV_TIMER_NOT_ALLOCATED , rtcdrvTimerTypePeriodic , SL_MIN , SLEEP_SleepBlockBegin() , and sleepEM3 .

Ecode_t RTCDRV_StopTimer ( RTCDRV_TimerID_t id )

Stop a given timer.

Parameters
[in] id The ID of the timer to stop.
Returns
ECODE_EMDRV_RTCDRV_OK on success.
ECODE_EMDRV_RTCDRV_ILLEGAL_TIMER_ID if the ID has an illegal value.
ECODE_EMDRV_RTCDRV_TIMER_NOT_ALLOCATED if the timer is not reserved.
ECODE_EMDRV_RTCDRV_NOT_INITIALIZED if the driver is not initialized.

Definition at line 724 of file rtcdriver.c .

References CORE_DECLARE_IRQ_STATE , CORE_ENTER_ATOMIC , CORE_EXIT_ATOMIC , ECODE_EMDRV_RTCDRV_ILLEGAL_TIMER_ID , ECODE_EMDRV_RTCDRV_NOT_INITIALIZED , ECODE_EMDRV_RTCDRV_OK , and ECODE_EMDRV_RTCDRV_TIMER_NOT_ALLOCATED .

uint32_t RTCDRV_TicksToMsec ( uint64_t ticks )

Convert from RTC/RTCC ticks to milliseconds.

Parameters
[in] ticks Number of ticks to convert.
Returns
A number of milliseconds.

Definition at line 961 of file rtcdriver.c .

uint64_t RTCDRV_TicksToMsec64 ( uint64_t ticks )

Convert from RTC/RTCC ticks to milliseconds with 64-bit resolution.

Parameters
[in] ticks Number of ticks to convert.
Returns
A number of milliseconds as a 64-bit value.

Definition at line 975 of file rtcdriver.c .

uint32_t RTCDRV_TicksToSec ( uint64_t ticks )

Convert from RTC/RTCC ticks to seconds.

Parameters
[in] ticks Number of ticks to convert.
Returns
A number of seconds.

Definition at line 991 of file rtcdriver.c .

Ecode_t RTCDRV_TimeRemaining ( RTCDRV_TimerID_t id,
uint32_t * timeRemaining
)

Get time left before a given timer expires.

Parameters
[in] id The ID of the timer to query.
[out] timeRemaining Time left expressed in milliseconds. Only valid if the return status is ECODE_EMDRV_RTCDRV_OK.
Returns
ECODE_EMDRV_RTCDRV_OK on success.
ECODE_EMDRV_RTCDRV_ILLEGAL_TIMER_ID if the ID has an illegal value.
ECODE_EMDRV_RTCDRV_TIMER_NOT_ALLOCATED if the timer is not reserved.
ECODE_EMDRV_RTCDRV_TIMER_NOT_RUNNING if the timer is not running.
ECODE_EMDRV_RTCDRV_PARAM_ERROR if an invalid timeRemaining pointer was supplied.
ECODE_EMDRV_RTCDRV_NOT_INITIALIZED if the driver is not initialized.

Definition at line 767 of file rtcdriver.c .

References CORE_DECLARE_IRQ_STATE , CORE_ENTER_ATOMIC , CORE_EXIT_ATOMIC , ECODE_EMDRV_RTCDRV_ILLEGAL_TIMER_ID , ECODE_EMDRV_RTCDRV_NOT_INITIALIZED , ECODE_EMDRV_RTCDRV_OK , ECODE_EMDRV_RTCDRV_PARAM_ERROR , ECODE_EMDRV_RTCDRV_TIMER_NOT_ALLOCATED , and ECODE_EMDRV_RTCDRV_TIMER_NOT_RUNNING .