Low level interface to the low power ticker of a target. More...

Modules
	Low Power Ticker tests
	Tests to validate the proper implementation of the low power ticker.

	Ticker Hal
	Low level interface to the ticker of a target.

	Ticker Tests
	Tests to validate the proper implementation of a ticker.

Functions
ticker_irq_handler_type	set_lp_ticker_irq_handler (ticker_irq_handler_type ticker_irq_handler)
	Set low power ticker IRQ handler. More...

const ticker_data_t *	get_lp_ticker_data (void)
	Get low power ticker's data. More...

void	lp_ticker_irq_handler (void)
	The wrapper for ticker_irq_handler, to pass lp ticker's data. More...

void	lp_ticker_init (void)
	Initialize the low power ticker. More...

void	lp_ticker_free (void)
	Deinitialize the lower power ticker. More...

uint32_t	lp_ticker_read (void)
	Read the current tick. More...

void	lp_ticker_set_interrupt (timestamp_t timestamp)
	Set interrupt for specified timestamp. More...

void	lp_ticker_disable_interrupt (void)
	Disable low power ticker interrupt. More...

void	lp_ticker_clear_interrupt (void)
	Clear the low power ticker interrupt. More...

void	lp_ticker_fire_interrupt (void)
	Set pending interrupt that should be fired right away. More...

const ticker_info_t *	lp_ticker_get_info (void)
	Get frequency and counter bits of this ticker. More...

Detailed Description

Low level interface to the low power ticker of a target.

Defined behavior

Has a reported frequency between 4KHz and 64KHz - verified by lp_ticker_info_test
Has a counter that is at least 12 bits wide - verified by lp_ticker_info_test
Continues operating in deep sleep mode - verified by lp_ticker_deepsleep_test
All behavior defined by the ticker specification

Undefined behavior

See the ticker specification
Calling any function other than lp_ticker_init after calling lp_ticker_free

Potential bugs

Glitches due to ripple counter - Verified by lp_ticker_glitch_test

See also: Low Power Ticker tests

Function Documentation

const ticker_data_t* get_lp_ticker_data ( void )

Get low power ticker's data.

Returns: The low power ticker data

void lp_ticker_clear_interrupt ( void )

Clear the low power ticker interrupt.

Pseudo Code:

 void lp_ticker_clear_interrupt(void)
 {
     // Write to the ICR (interrupt clear register) of the LPTMR
     LPTMR_ICR = LPTMR_ICR_COMPARE_Msk;
 }

void lp_ticker_disable_interrupt ( void )

Disable low power ticker interrupt.

Pseudo Code:

 void lp_ticker_disable_interrupt(void)
 {
     // Disable the compare interrupt
     LPTMR_CTRL &= ~LPTMR_CTRL_COMPARE_ENABLE_Msk;
 }

void lp_ticker_fire_interrupt ( void )

Set pending interrupt that should be fired right away.

Pseudo Code:

 void lp_ticker_fire_interrupt(void)
 {
     NVIC_SetPendingIRQ(LPTMR_IRQn);
 }

void lp_ticker_free ( void )

Deinitialize the lower power ticker.

Powerdown the lp ticker in preparation for sleep, powerdown, or reset.

After calling this function no other ticker functions should be called except lp_ticker_init(). Calling any function other than init after freeing is undefined.

Note: This function stops the ticker from counting.

const ticker_info_t* lp_ticker_get_info ( void )

Get frequency and counter bits of this ticker.

Pseudo Code:

 const ticker_info_t* lp_ticker_get_info()
 {
     static const ticker_info_t info = {
         32768,      // 32KHz
         16          // 16 bit counter
     };
     return &info;
 }

void lp_ticker_init ( void )

Initialize the low power ticker.

Initialize or re-initialize the ticker. This resets all the clocking and prescaler registers, along with disabling the compare interrupt.

Pseudo Code:

 void lp_ticker_init()
 {
     // Enable clock gate so processor can read LPTMR registers
     POWER_CTRL |= POWER_CTRL_LPTMR_Msk;
 
     // Disable the timer and ensure it is powered down
     LPTMR_CTRL &= ~(LPTMR_CTRL_ENABLE_Msk | LPTMR_CTRL_COMPARE_ENABLE_Msk);
 
     // Configure divisors - no division necessary
     LPTMR_PRESCALE = 0;
     LPTMR_CTRL |= LPTMR_CTRL_ENABLE_Msk;
 
     // Install the interrupt handler
     NVIC_SetVector(LPTMR_IRQn, (uint32_t)lp_ticker_irq_handler);
     NVIC_EnableIRQ(LPTMR_IRQn);
 }

void lp_ticker_irq_handler ( void )

The wrapper for ticker_irq_handler, to pass lp ticker's data.

uint32_t lp_ticker_read ( void )

Read the current tick.

If no rollover has occurred, the seconds passed since lp_ticker_init() was called can be found by dividing the ticks returned by this function by the frequency returned by lp_ticker_get_info.

Returns: The current timer's counter value in ticks

Pseudo Code:

 uint32_t lp_ticker_read()
 {
     uint16_t count;
     uint16_t last_count;
 
     // Loop until the same tick is read twice since this
     // is ripple counter on a different clock domain.
     count = LPTMR_COUNT;
     do {
         last_count = count;
         count = LPTMR_COUNT;
     } while (last_count != count);
 
     return count;
 }

void lp_ticker_set_interrupt ( timestamp_t timestamp )

Set interrupt for specified timestamp.

Parameters

timestamp The time in ticks to be set

Note: no special handling needs to be done for times in the past as the common timer code will detect this and call lp_ticker_fire_interrupt() if this is the case; calling this function with timestamp of more than the supported number of bits returned by lp_ticker_get_info results in undefined behavior.

Pseudo Code:

 void lp_ticker_set_interrupt(timestamp_t timestamp)
 {
     LPTMR_COMPARE = timestamp;
     LPTMR_CTRL |= LPTMR_CTRL_COMPARE_ENABLE_Msk;
 }

ticker_irq_handler_type set_lp_ticker_irq_handler ( ticker_irq_handler_type ticker_irq_handler )

Set low power ticker IRQ handler.

Parameters

ticker_irq_handler IRQ handler to be connected

Returns: previous ticker IRQ handler

Note: by default IRQ handler is set to ticker_irq_handler; this function is primarily for testing purposes and it's not required part of HAL implementation

Modules

Functions

Detailed Description

Defined behavior

Undefined behavior

Potential bugs

Function Documentation

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