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lp_ticker_api.h
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lp_ticker_api.h
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/** \addtogroup hal */
/** @{*/
/* mbed Microcontroller Library
* Copyright (c) 2015 ARM Limited
* SPDX-License-Identifier: Apache-2.0
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef MBED_LPTICKER_API_H
#define MBED_LPTICKER_API_H
#include "device.h"
#if DEVICE_LPTICKER
#include "hal/ticker_api.h"
#ifdef __cplusplus
extern "C" {
#endif
/**
* \defgroup hal_lp_ticker Low Power Ticker
* 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 @ref hal_ticker_shared "ticker specification"
*
* # Undefined behavior
* * See the @ref hal_ticker_shared "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 hal_lp_ticker_tests
*
* @{
*/
/**
* \defgroup hal_lp_ticker_tests Low Power Ticker tests
* Tests to validate the proper implementation of the low power ticker
*
* To run the low power ticker hal tests use the command:
*
* mbed test -t <toolchain> -m <target> -n tests-mbed_hal-common_ticker*,tests-mbed_hal-lp_ticker*
*
*/
typedef void (*ticker_irq_handler_type)(const ticker_data_t *const);
/** Set low power ticker IRQ handler
*
* @param ticker_irq_handler IRQ handler to be connected
*
* @return previous ticker IRQ handler
*
* @note by default IRQ handler is set to ::ticker_irq_handler
* @note this function is primarily for testing purposes and it's not required part of HAL implementation
*
*/
ticker_irq_handler_type set_lp_ticker_irq_handler(ticker_irq_handler_type ticker_irq_handler);
/** Get low power ticker's data
*
* @return The low power ticker data
*/
const ticker_data_t *get_lp_ticker_data(void);
/** The wrapper for ticker_irq_handler, to pass lp ticker's data
*
*/
void lp_ticker_irq_handler(void);
/* HAL lp ticker */
/** 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:
* @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);
* }
* @endcode
*/
void lp_ticker_init(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.
*/
void lp_ticker_free(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.
*
* @return The current timer's counter value in ticks
*
* Pseudo Code:
* @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;
* }
* @endcode
*/
uint32_t lp_ticker_read(void);
/** Set interrupt for specified timestamp
*
* @param 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
*
* @note 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:
* @code
* void lp_ticker_set_interrupt(timestamp_t timestamp)
* {
* LPTMR_COMPARE = timestamp;
* LPTMR_CTRL |= LPTMR_CTRL_COMPARE_ENABLE_Msk;
* }
* @endcode
*/
void lp_ticker_set_interrupt(timestamp_t timestamp);
/** Disable low power ticker interrupt
*
* Pseudo Code:
* @code
* void lp_ticker_disable_interrupt(void)
* {
* // Disable the compare interrupt
* LPTMR_CTRL &= ~LPTMR_CTRL_COMPARE_ENABLE_Msk;
* }
* @endcode
*/
void lp_ticker_disable_interrupt(void);
/** Clear the low power ticker interrupt
*
* Pseudo Code:
* @code
* void lp_ticker_clear_interrupt(void)
* {
* // Write to the ICR (interrupt clear register) of the LPTMR
* LPTMR_ICR = LPTMR_ICR_COMPARE_Msk;
* }
* @endcode
*/
void lp_ticker_clear_interrupt(void);
/** Set pending interrupt that should be fired right away.
*
* Pseudo Code:
* @code
* void lp_ticker_fire_interrupt(void)
* {
* NVIC_SetPendingIRQ(LPTMR_IRQn);
* }
* @endcode
*/
void lp_ticker_fire_interrupt(void);
/** Get frequency and counter bits of this ticker.
*
* Pseudo Code:
* @code
* const ticker_info_t* lp_ticker_get_info()
* {
* static const ticker_info_t info = {
* 32768, // 32KHz
* 16 // 16 bit counter
* };
* return &info;
* }
* @endcode
*/
const ticker_info_t *lp_ticker_get_info(void);
/**@}*/
#ifdef __cplusplus
}
#endif
#endif
#endif
/** @}*/