CRYOTIMER - Ultra Low Energy Timer
Description
Ultra Low Energy Timer/Counter (CRYOTIMER) Peripheral API.
The CRYOTIMER is a 32 bit counter which operates on a low-frequency oscillator and is capable of running in all Energy Modes. It can provide periodic wakeup events and PRS signals which can be used to wake up peripherals from any energy mode. The CRYOTIMER provides a very wide range of periods for the interrupts facilitating flexible ultra-low energy operation. Because of its simplicity, the CRYOTIMER is a lower energy solution for periodically waking up the MCU compared to the RTCC.
To configure the CRYOTIMER, call the CRYOTIMER_Init function. This function will configure the CRYOTIMER peripheral according to the user configuration.
When using the CRYOTIMER, choose which oscillator to use as the CRYOTIMER clock. The CRYOTIMER supports 3 low-frequency clocks LFXO, LFRCO, and ULFRCO. The oscillator that is chosen must be enabled and ready before calling this CRYOTIMER_Init function. See CMU_OscillatorEnable for details of how to enable and wait for an oscillator to become ready. Note that ULFRCO is always ready while LFRCO cmuOsc_LFRCO and LFXO cmuOsc_LFXO must be enabled by the user.
Note that the only oscillator which is running in EM3 is ULFRCO. Keep this in mind when choosing which oscillator to use for the CRYOTIMER.
This example shows how to use the CRYOTIMER to generate an interrupt at a configurable period.
To use the CRYOTIMER in EM4, enable EM4 wakeup in the CRYOTIMER. This can be done either in the CRYOTIMER_Init_TypeDef structure when initializing the CRYOTIMER or at a later time by using CRYOTIMER_EM4WakeupEnable .
Note that when using the CRYOTIMER to wake up from EM4, the application has the responsibility to clear the wakeup event. This is done by calling CRYOTIMER_IntClear . If the user does not clear the wakeup event, the wakeup event will stay pending and will cause an immediate wakeup the next time the application attempts to enter EM4.
This example shows how to use the CRYOTIMER to wake up from EM4 after a configurable amount of time.
All the low frequency oscillators can be used in EM4, however, the oscillator that is used must be be configured to be retained when going into EM4. This can be configured by using functions in the EMU - Energy Management Unit module. See EMU_EM4Init and EMU_EM4Init_TypeDef . If an oscillator is retained in EM4, the user is also responsible for unlatching the retained configuration on a wakeup from EM4.
Data Structures |
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struct | CRYOTIMER_Init_TypeDef |
CRYOTIMER initialization structure.
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Functions |
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void | CRYOTIMER_IntClear (uint32_t flags) |
Clear the CRYOTIMER period interrupt.
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uint32_t | CRYOTIMER_IntGet (void) |
Get the CRYOTIMER interrupt flag.
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uint32_t | CRYOTIMER_IntGetEnabled (void) |
Get enabled and pending CRYOTIMER interrupt flags.
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void | CRYOTIMER_IntEnable (uint32_t flags) |
Enable one or more CRYOTIMER interrupts.
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void | CRYOTIMER_IntDisable (uint32_t flags) |
Disable one or more CRYOTIMER interrupts.
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void | CRYOTIMER_IntSet (uint32_t flags) |
Set the CRYOTIMER period interrupt flag.
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void | CRYOTIMER_PeriodSet (uint32_t period) |
Set the CRYOTIMER period select.
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uint32_t | CRYOTIMER_PeriodGet (void) |
Get the CRYOTIMER period select value.
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uint32_t | CRYOTIMER_CounterGet (void) |
Get the CRYOTIMER counter value.
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void | CRYOTIMER_EM4WakeupEnable (bool enable) |
Enable/disable EM4 wakeup capability.
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void | CRYOTIMER_Enable (bool enable) |
Enable/disable the CRYOTIMER.
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void | CRYOTIMER_Init (const CRYOTIMER_Init_TypeDef *init) |
Initialize the CRYOTIMER.
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Macros |
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#define | CRYOTIMER_INIT_DEFAULT |
Default CRYOTIMER init structure.
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Function Documentation
◆ CRYOTIMER_IntClear()
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inline |
Clear the CRYOTIMER period interrupt.
- Parameters
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[in] flags
CRYOTIMER interrupt sources to clear. Use CRYOTIMER_IFC_PERIOD.
◆ CRYOTIMER_IntGet()
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inline |
Get the CRYOTIMER interrupt flag.
- Note
- This function does not clear event bits.
- Returns
- Pending CRYOTIMER interrupt sources. The only interrupt source available for the CRYOTIMER is CRYOTIMER_IF_PERIOD.
◆ CRYOTIMER_IntGetEnabled()
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inline |
Get enabled and pending CRYOTIMER interrupt flags.
Useful for handling more interrupt sources in the same interrupt handler.
- Note
- This function does not clear interrupt flags.
- Returns
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Pending and enabled CRYOTIMER interrupt sources. The return value is the bitwise AND of
- the enabled interrupt sources in CRYOTIMER_IEN and
- the pending interrupt flags CRYOTIMER_IF
◆ CRYOTIMER_IntEnable()
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inline |
Enable one or more CRYOTIMER interrupts.
- Parameters
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[in] flags
CRYOTIMER interrupt sources to enable. Use CRYOTIMER_IEN_PERIOD.
◆ CRYOTIMER_IntDisable()
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inline |
Disable one or more CRYOTIMER interrupts.
- Parameters
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[in] flags
CRYOTIMER interrupt sources to disable. Use CRYOTIMER_IEN_PERIOD.
◆ CRYOTIMER_IntSet()
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inline |
Set the CRYOTIMER period interrupt flag.
- Note
- Writes 1 to the interrupt flag set register.
- Parameters
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[in] flags
CRYOTIMER interrupt sources to set to pending. Use CRYOTIMER_IFS_PERIOD.
◆ CRYOTIMER_PeriodSet()
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inline |
Set the CRYOTIMER period select.
- Note
- Sets the duration between the interrupts/wakeup events based on the pre-scaled clock.
- Parameters
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[in] period
2^period is the number of clock cycles before a wakeup event or interrupt is triggered. The CRYOTIMER_Periodsel_TypeDef enumeration can be used a convenience type when calling this function.
◆ CRYOTIMER_PeriodGet()
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inline |
Get the CRYOTIMER period select value.
- Note
- Gets the duration between the interrupts/wakeup events in the CRYOTIMER.
- Returns
- Duration between the interrupts/wakeup events. Returns the value of the PERIODSEL register. The number of clock cycles can be calculated as the 2^n where n is the return value of this function.
◆ CRYOTIMER_CounterGet()
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inline |
Get the CRYOTIMER counter value.
- Returns
- Returns the current CRYOTIMER counter value.
◆ CRYOTIMER_EM4WakeupEnable()
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inline |
Enable/disable EM4 wakeup capability.
- Parameters
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[in] enable
True to enable EM4 wakeup, false to disable.
◆ CRYOTIMER_Enable()
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inline |
Enable/disable the CRYOTIMER.
- Parameters
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[in] enable
True to enable the CRYOTIMER, false to disable.
◆ CRYOTIMER_Init()
void CRYOTIMER_Init | ( | const CRYOTIMER_Init_TypeDef * |
init
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Initialize the CRYOTIMER.
Use this function to initialize the CRYOTIMER. Select a prescaler setting and select a low-frequency oscillator. See the configuration structure CRYOTIMER_Init_TypeDef for more details.
- Parameters
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[in] init
A pointer to the initialization structure.
Macro Definition Documentation
◆ CRYOTIMER_INIT_DEFAULT
#define CRYOTIMER_INIT_DEFAULT |
Default CRYOTIMER init structure.
Enumeration Type Documentation
◆ CRYOTIMER_Presc_TypeDef
Prescaler selection.
◆ CRYOTIMER_Osc_TypeDef
◆ CRYOTIMER_Period_TypeDef
Period selection value.