mirror of https://github.com/ARMmbed/mbed-os.git
303 lines
8.9 KiB
C
303 lines
8.9 KiB
C
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/** \addtogroup hal */
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/** @{*/
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/* mbed Microcontroller Library
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* Copyright (c) 2006-2015 ARM Limited
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* SPDX-License-Identifier: Apache-2.0
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef MBED_US_TICKER_API_H
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#define MBED_US_TICKER_API_H
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#include <stdint.h>
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#include "hal/ticker_api.h"
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#ifdef __cplusplus
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extern "C" {
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#endif
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/**
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* \defgroup hal_us_ticker Microsecond Ticker
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* Low level interface to the microsecond ticker of a target
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*
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* # Defined behavior
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* * Has a reported frequency between 250KHz and 8MHz - Verified by test ::us_ticker_info_test
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* * Has a counter that is at least 16 bits wide - Verified by test ::us_ticker_info_test
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* * All behavior defined by the @ref hal_ticker_shared "ticker specification"
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*
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* # Undefined behavior
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* * See the @ref hal_ticker_shared "ticker specification"
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*
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* @see hal_us_ticker_tests
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*
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* @{
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*/
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/**
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* \defgroup hal_us_ticker_tests Microsecond Ticker tests
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* Tests to validate the proper implementation of the microsecond ticker
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*
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* To run the microsecond ticker hal tests use the command:
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*
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* mbed test -t <toolchain> -m <target> -n tests-mbed_hal-common_ticker*,tests-mbed_hal-us_ticker*
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*
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* @see hal_ticker_tests
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*
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*/
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/**
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* \defgroup hal_ticker_shared Ticker Hal
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* Low level interface to the ticker of a target
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*
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* # Defined behavior
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* * The function ticker_init is safe to call repeatedly - Verified by test ::ticker_init_test
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* * The function ticker_init allows the ticker to keep counting and disables the ticker interrupt - Verified by test ::ticker_init_test
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* * Ticker frequency is non-zero and counter is at least 8 bits - Verified by ::ticker_info_test
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* * The ticker rolls over at (1 << bits) and continues counting starting from 0 - Verified by ::ticker_overflow_test
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* * The ticker counts at the specified frequency +- 10% - Verified by ::ticker_frequency_test
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* * The ticker increments by 1 each tick - Verified by ::ticker_increment_test
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* * The ticker interrupt fires only when the ticker times increments to or past the value set by ticker_set_interrupt.
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* Verified by ::ticker_interrupt_test and ::ticker_past_test
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* * It is safe to call ticker_set_interrupt repeatedly before the handler is called - Verified by ::ticker_repeat_reschedule_test
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* * The function ticker_fire_interrupt causes ticker_irq_handler to be called immediately from interrupt context -
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* Verified by ::ticker_fire_now_test
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* * The ticker operations ticker_read, ticker_clear_interrupt, ticker_set_interrupt and ticker_fire_interrupt
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* take less than 20us to complete - Verified by ::ticker_speed_test
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*
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* # Undefined behavior
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* * Calling any function other than ticker_init before the initialization of the ticker
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* * Whether ticker_irq_handler is called a second time if the time wraps and matches the value set by ticker_set_interrupt again
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* * Calling ticker_set_interrupt with a value that has more than the supported number of bits
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* * Calling any function other than us_ticker_init after calling us_ticker_free
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*
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* # Potential bugs
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* * Drift due to reschedule - Verified by ::ticker_repeat_reschedule_test
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* * Incorrect overflow handling of timers - Verified by ::ticker_overflow_test
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* * Interrupting at a time of 0 - Verified by ::ticker_overflow_test
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* * Interrupt triggered more than once - Verified by ::ticker_interrupt_test
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*
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* @ingroup hal_us_ticker
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* @ingroup hal_lp_ticker
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*/
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/**
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* \defgroup hal_ticker_tests Ticker Tests
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* Tests to validate the proper implementation of a ticker
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*
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* To run the ticker hal tests use the command:
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*
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* mbed test -t <toolchain> -m <target> -n tests-mbed_hal-common_ticker*
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*
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* @ingroup hal_us_ticker
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* @ingroup hal_lp_ticker
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*/
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typedef void (*ticker_irq_handler_type)(const ticker_data_t *const);
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/** Set ticker IRQ handler
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*
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* @param ticker_irq_handler IRQ handler to be connected
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*
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* @return previous ticker IRQ handler
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*
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* @note by default IRQ handler is set to ::ticker_irq_handler
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* @note this function is primarily for testing purposes and it's not required part of HAL implementation
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*
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*/
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ticker_irq_handler_type set_us_ticker_irq_handler(ticker_irq_handler_type ticker_irq_handler);
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/** Get ticker's data
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*
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* @return The microsecond ticker data
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*/
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const ticker_data_t *get_us_ticker_data(void);
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/** The wrapper for ticker_irq_handler, to pass us ticker's data
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*
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*/
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void us_ticker_irq_handler(void);
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/* HAL us ticker */
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/** Initialize the ticker
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*
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* Initialize or re-initialize the ticker. This resets all the
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* clocking and prescaler registers, along with disabling
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* the compare interrupt.
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*
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* @note Initialization properties tested by ::ticker_init_test
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*
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* Pseudo Code:
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* @code
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* void us_ticker_init()
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* {
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* // Enable clock gate so processor can read TIMER registers
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* POWER_CTRL |= POWER_CTRL_TIMER_Msk;
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*
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* // Disable the timer and ensure it is powered down
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* TIMER_CTRL &= ~(TIMER_CTRL_ENABLE_Msk | TIMER_CTRL_COMPARE_ENABLE_Msk);
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*
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* // Configure divisors
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* uint32_t prescale = SystemCoreClock / 1000000;
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* TIMER_PRESCALE = prescale - 1;
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* TIMER_CTRL |= TIMER_CTRL_ENABLE_Msk;
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*
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* // Install the interrupt handler
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* NVIC_SetVector(TIMER_IRQn, (uint32_t)us_ticker_irq_handler);
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* NVIC_EnableIRQ(TIMER_IRQn);
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* }
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* @endcode
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*/
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void us_ticker_init(void);
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/** Deinitialize the us ticker
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*
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* Powerdown the us ticker in preparation for sleep, powerdown, or reset.
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*
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* After this function is called, no other ticker functions should be called
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* except us_ticker_init(), calling any function other than init is undefined.
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*
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* @note This function stops the ticker from counting.
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*
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* Pseudo Code:
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* @code
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* uint32_t us_ticker_free()
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* {
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* // Disable timer
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* TIMER_CTRL &= ~TIMER_CTRL_ENABLE_Msk;
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*
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* // Disable the compare interrupt
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* TIMER_CTRL &= ~TIMER_CTRL_COMPARE_ENABLE_Msk;
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*
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* // Disable timer interrupt
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* NVIC_DisableIRQ(TIMER_IRQn);
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*
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* // Disable clock gate so processor cannot read TIMER registers
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* POWER_CTRL &= ~POWER_CTRL_TIMER_Msk;
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* }
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* @endcode
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*
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*/
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void us_ticker_free(void);
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/** Read the current counter
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*
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* Read the current counter value without performing frequency conversions.
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* If no rollover has occurred, the seconds passed since us_ticker_init()
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* was called can be found by dividing the ticks returned by this function
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* by the frequency returned by ::us_ticker_get_info.
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*
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* @return The current timer's counter value in ticks
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*
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* Pseudo Code:
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* @code
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* uint32_t us_ticker_read()
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* {
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* return TIMER_COUNT;
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* }
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* @endcode
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*/
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uint32_t us_ticker_read(void);
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/** Set interrupt for specified timestamp
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*
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* @param timestamp The time in ticks to be set
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*
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* @note no special handling needs to be done for times in the past
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* as the common timer code will detect this and call
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* us_ticker_fire_interrupt() if this is the case
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*
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* @note calling this function with timestamp of more than the supported
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* number of bits returned by ::us_ticker_get_info results in undefined
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* behavior.
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*
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* Pseudo Code:
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* @code
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* void us_ticker_set_interrupt(timestamp_t timestamp)
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* {
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* TIMER_COMPARE = timestamp;
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* TIMER_CTRL |= TIMER_CTRL_COMPARE_ENABLE_Msk;
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* }
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* @endcode
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*/
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void us_ticker_set_interrupt(timestamp_t timestamp);
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/** Disable us ticker interrupt
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*
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* Pseudo Code:
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* @code
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* void us_ticker_disable_interrupt(void)
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* {
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* // Disable the compare interrupt
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* TIMER_CTRL &= ~TIMER_CTRL_COMPARE_ENABLE_Msk;
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* }
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* @endcode
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*/
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void us_ticker_disable_interrupt(void);
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/** Clear us ticker interrupt
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*
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* Pseudo Code:
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* @code
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* void us_ticker_clear_interrupt(void)
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* {
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* // Write to the ICR (interrupt clear register) of the TIMER
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* TIMER_ICR = TIMER_ICR_COMPARE_Msk;
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* }
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* @endcode
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*/
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void us_ticker_clear_interrupt(void);
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/** Set pending interrupt that should be fired right away.
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*
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* The ticker should be initialized prior calling this function.
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*
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* Pseudo Code:
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* @code
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* void us_ticker_fire_interrupt(void)
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* {
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* NVIC_SetPendingIRQ(TIMER_IRQn);
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* }
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* @endcode
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*/
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void us_ticker_fire_interrupt(void);
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/** Get frequency and counter bits of this ticker.
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*
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* Pseudo Code:
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* @code
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* const ticker_info_t* us_ticker_get_info()
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* {
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* static const ticker_info_t info = {
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* 1000000, // 1 MHz
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* 32 // 32 bit counter
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* };
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* return &info;
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* }
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* @endcode
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*/
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const ticker_info_t *us_ticker_get_info(void);
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/**@}*/
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#ifdef __cplusplus
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}
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#endif
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#endif
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/** @}*/
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