synth_pwm.h 2.2KB

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  1. /* Audio Library for Teensy 3.X
  2. * Copyright (c) 2017, Paul Stoffregen, paul@pjrc.com
  3. *
  4. * Development of this audio library was funded by PJRC.COM, LLC by sales of
  5. * Teensy and Audio Adaptor boards. Please support PJRC's efforts to develop
  6. * open source software by purchasing Teensy or other PJRC products.
  7. *
  8. * Permission is hereby granted, free of charge, to any person obtaining a copy
  9. * of this software and associated documentation files (the "Software"), to deal
  10. * in the Software without restriction, including without limitation the rights
  11. * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  12. * copies of the Software, and to permit persons to whom the Software is
  13. * furnished to do so, subject to the following conditions:
  14. *
  15. * The above copyright notice, development funding notice, and this permission
  16. * notice shall be included in all copies or substantial portions of the Software.
  17. *
  18. * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  19. * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  20. * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  21. * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  22. * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  23. * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  24. * THE SOFTWARE.
  25. */
  26. #ifndef synth_pwm_h_
  27. #define synth_pwm_h_
  28. #include "Arduino.h"
  29. #include "AudioStream.h"
  30. #include "arm_math.h"
  31. class AudioSynthWaveformPWM : public AudioStream
  32. {
  33. public:
  34. AudioSynthWaveformPWM() : AudioStream(1, inputQueueArray), magnitude(0), elapsed(0) {}
  35. void frequency(float freq) {
  36. if (freq < 1.0) freq = 1.0;
  37. else if (freq > AUDIO_SAMPLE_RATE_EXACT/4) freq = AUDIO_SAMPLE_RATE_EXACT/4;
  38. //phase_increment = freq * (4294967296.0 / AUDIO_SAMPLE_RATE_EXACT);
  39. duration = (AUDIO_SAMPLE_RATE_EXACT * 65536.0 + freq) / (freq * 2.0);
  40. }
  41. void amplitude(float n) {
  42. if (n < 0) n = 0;
  43. else if (n > 1.0) n = 1.0;
  44. magnitude = n * 32767.0;
  45. }
  46. virtual void update(void);
  47. private:
  48. uint32_t duration; // samples per half cycle (when 50% duty) * 65536
  49. audio_block_t *inputQueueArray[1];
  50. int32_t magnitude;
  51. uint32_t elapsed;
  52. };
  53. #endif