square_wave.h

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//   Copyright 2016-2023 Jean-Francois Poilpret
//
//   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 SQUARE_WAVE_HH
#define SQUARE_WAVE_HH
 
#include "timer.h"
#include "pwm.h"
 
namespace timer
{
    template<board::Timer NTIMER_, board::PWMPin OUTPUT_> class SquareWave
    {
    public:
        SquareWave(const SquareWave&) = delete;
        SquareWave& operator=(const SquareWave&) = delete;
        
        static constexpr const board::Timer NTIMER = NTIMER_;
        static constexpr const board::PWMPin OUTPUT = OUTPUT_;
        static constexpr const board::DigitalPin PIN = board_traits::PWMPin_trait<OUTPUT>::ACTUAL_PIN;
 
        using CALC = timer::Calculator<NTIMER>;
        using TIMER = timer::Timer<NTIMER>;
        using PWMPIN = analog::PWMOutput<OUTPUT>;
 
        SquareWave() : output_{timer_, timer::TimerOutputMode::TOGGLE}
        {
            using TRAIT = board_traits::PWMPin_trait<OUTPUT>;
            static_assert(TRAIT::COM == 0, "Only OCnA pin is supported for wave generation");
        }
 
        const TIMER& timer() const
        {
            return timer_;
        }
 
        TIMER& timer()
        {
            return timer_;
        }
 
        void start_frequency(uint32_t frequency)
        {
            const uint32_t period = ONE_SECOND / 2 / frequency;
            typename TIMER::PRESCALER prescaler = CALC::CTC_prescaler(period);
            start_frequency(prescaler, CALC::CTC_counter(prescaler, period));
        }
 
        void start_frequency(typename TIMER::PRESCALER prescaler, typename TIMER::TYPE counter)
        {
            timer_.end();
            timer_.set_prescaler(prescaler);
            timer_.begin();
            output_.set_duty(counter);
        }
 
        void stop()
        {
            timer_.end();
            output_.set_duty(0);
        }
 
    private:
        TIMER timer_ = TIMER{timer::TimerMode::CTC, TIMER::PRESCALER::NO_PRESCALING};
        PWMPIN output_;
    };
}
 
#endif /* SQUARE_WAVE_HH */