Mbed OS Reference | Ticker.h Source File

 /* mbed Microcontroller Library
  * Copyright (c) 2006-2019 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_TICKER_H
 #define MBED_TICKER_H
 
 #include <chrono>
 #include <mstd_utility>
 #include "drivers/TickerDataClock.h"
 #include "drivers/TimerEvent.h"
 #include "platform/Callback.h"
 #include "platform/mbed_toolchain.h"
 #include "platform/NonCopyable.h"
 #include "hal/lp_ticker_api.h"
 
 namespace mbed {
 
 /**
  * \defgroup drivers_Ticker Ticker class
  * \ingroup drivers-public-api-ticker
  * @{
  */
 
 /** A Ticker is used to call a function at a recurring interval
  *
  *  You can use as many separate Ticker objects as you require.
  *
  * @note Synchronization level: Interrupt safe
  *
  * Example:
  * @code
  * // Toggle the blinking LED after 5 seconds
  *
  * #include "mbed.h"
  * using namespace std::chrono;
  *
  * Ticker timer;
  * DigitalOut led1(LED1);
  * DigitalOut led2(LED2);
  *
  * int flip = 0;
  *
  * void attime() {
  *     flip = !flip;
  * }
  *
  * int main() {
  *     timer.attach(&attime, 5us);
  *     while(1) {
  *         if(flip == 0) {
  *             led1 = !led1;
  *         } else {
  *             led2 = !led2;
  *         }
  *         ThisThread::sleep_for(200ms);
  *     }
  * }
  * @endcode
  */
 class TickerBase : public TimerEvent, private NonCopyable<TickerBase> {
 public:
     /** Attach a function to be called by the Ticker, specifying the interval in seconds
      *
      *  The method forwards its arguments to attach_us() rather than copying them which
      *  may not be trivial depending on the callback copied.
      *  The function is forcibly inlined to not use floating-point operations. This is
      *  possible given attach_us() expects an integer value for the callback interval.
      *  @param func pointer to the function to be called
      *  @param t the time between calls in seconds
      *  @deprecated Pass a chrono duration, not a float second count. For example use `10ms` rather than `0.01f`.
      */
 #if defined(__ICCARM__)
     MBED_DEPRECATED_SINCE("mbed-os-6.0.0", "Pass a chrono duration, not a float second count. For example use `10ms` rather than `0.01f`.")
     MBED_FORCEINLINE template <typename F>
 #else
     template <typename F> MBED_FORCEINLINE
     MBED_DEPRECATED_SINCE("mbed-os-6.0.0", "Pass a chrono duration, not a float second count. For example use `10ms` rather than `0.01f`.")
 #endif
     void attach(F &&func, float t)
     {
         auto float_interval = std::chrono::duration<float>(t);
         attach(std::forward<F>(func), std::chrono::duration_cast<std::chrono::microseconds>(float_interval));
     }
 
     /** Attach a function to be called by the Ticker, specifying the interval in microseconds
      *
      *  @param func pointer to the function to be called
      *  @param t the time between calls in micro-seconds
      *
      *  @note setting @a t to a value shorter than it takes to process the ticker callback
      *  causes the system to hang. Ticker callback is called constantly with no time
      *  for threads scheduling.
      *  @deprecated Pass a chrono duration, not an integer microsecond count. For example use `10ms` rather than `10000`.
      *
      */
     MBED_DEPRECATED_SINCE("mbed-os-6.0.0", "Pass a chrono duration, not an integer microsecond count. For example use `10ms` rather than `10000`.")
     void attach_us(Callback<void()> func, us_timestamp_t t);
 
     /** Attach a function to be called by the Ticker, specifying the interval in microseconds
      *
      *  @param func pointer to the function to be called
      *  @param t the time between calls in micro-seconds
      *
      *  @note setting @a t to a value shorter than it takes to process the ticker callback
      *  causes the system to hang. Ticker callback is called constantly with no time
      *  for threads scheduling.
      *
      */
     void attach(Callback<void()> func, std::chrono::microseconds t);
 
     /** Detach the function
      */
     void detach();
 
 #if !defined(DOXYGEN_ONLY)
 protected:
     TickerBase(const ticker_data_t *data);
     TickerBase(const ticker_data_t *data, bool lock_deepsleep);
 
     ~TickerBase()
     {
         detach();
     }
 
     /** Attach a function to be called by the Ticker, specifying the absolute call time
      *
      *  If used, handler must be overridden, as TickerBase::handler would attempt
      *  to reschedule. This is done by `TimeoutBase` (used by `Timeout` and `LowPowerTimeout`).
      *
      *  @param func pointer to the function to be called
      *  @param abs_time the time for the call
      *
      *  @note setting @a abs_time to a time in the past means the event will be scheduled immediately
      *  resulting in an instant call to the function.
      */
     void attach_absolute(Callback<void()> func, TickerDataClock::time_point abs_time);
 
     void handler() override;
     std::chrono::microseconds  _delay{0};  /**< Time delay (in microseconds) for resetting the multishot callback. */
     Callback<void()>    _function;  /**< Callback. */
     bool          _lock_deepsleep;  /**< Flag which indicates if deep sleep should be disabled. */
 #endif
 private:
     void setup(std::chrono::microseconds t);
     void setup_absolute(TickerDataClock::time_point t);
 };
 
 class Ticker : public TickerBase {
 public:
     Ticker();
 };
 /** @}*/
 
 } // namespace mbed
 
 #endif
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