Tone Prototype

make_tone.cpp

template <class TonePin>
void make_tone(int frequency) {
    IO::DigitalOut<TonePin> tonePin;
    typename TonePin::TimerChannel channel;
    typename TonePin::TimerChannel::Timer timer;
    using PrescaleModes = typename TonePin::TimerChannel::Timer::PrescaleModes;
    using WaveformModes = typename TonePin::TimerChannel::Timer::WaveformModes;

    PrescaleModes mode = PrescaleModes::Stopped;
    int ocr = 0;

    frequency *= 2;
    for (uint8_t i = 0; i < timer.prescale_count; i++) {
        ocr = F_CPU / frequency / timer.prescale_values[i] - 1;
        if (ocr <= 255) {
            // Not exactly safe, but works for the 328p.
            mode = static_cast<PrescaleModes>(i+1);
            break;
        }
    }
    timer.reset_timer_control();

    timer.set_waveform(WaveformModes::CTC_OCRA);
    channel.set_output_compare(ocr);

    // Connect pin TonePin to timer to toggle on each compare match.
    channel.set_mode(Timers::CompareOutputMode::Mode1);

    timer.set_prescale(mode);
}