Mozzi  version v2.0
sound synthesis library for Arduino
Phasor.h
1 /*
2  * Phasor.h
3  *
4  * This file is part of Mozzi.
5  *
6  * Copyright 2012-2024 Tim Barrass and the Mozzi Team
7  *
8  * Mozzi is licensed under the GNU Lesser General Public Licence (LGPL) Version 2.1 or later.
9  *
10  */
11 
12 #ifndef PHASOR_H_
13 #define PHASOR_H_
14 
15 #include "Arduino.h"
16 #include "mozzi_fixmath.h"
17 
18 #define PHASOR_MAX_VALUE_UL 4294967295UL
19 
20 /** Phasor repeatedly generates a high resolution ramp at a variable frequency.
21 The output of Phasor.next() is an unsigned number between 0 and 4294967295, the
22 maximum that can be expressed by an unsigned 32 bit integer.
23 @tparam UPDATE_RATE the rate at which the Phasor will be updated,
24 usually MOZZI_CONTROL_RATE or MOZZI_AUDIO_RATE.
25 */
26 
27 template <unsigned int UPDATE_RATE>
28 class Phasor
29 {
30 private:
31  uint32_t current_value;
32  volatile uint32_t step_size;
33 
34 public:
35  /** Constructor. "Phasor <MOZZI_AUDIO_RATE> myphasor;"
36  makes a Phasor which updates at MOZZI_AUDIO_RATE.
37  */
38  Phasor (){
39  ;
40  }
41 
42  /** Increments one step along the phase.
43  @return the next value.
44  */
45  inline
47  {
48  current_value += step_size; // will wrap
49  return current_value;
50  }
51 
52  /** Set the current value of the phasor. The Phasor will continue incrementing from this
53  value using any previously calculated step size.
54  */
55  inline
56  void set(uint32_t value)
57  {
58  current_value=value;
59  }
60 
61 
62  /** Set the Phasor frequency with an unsigned int.
63  @param frequency is how many times per second to count from
64  0 to the maximum uint32_t value 4294967295.
65  @note Timing 8us
66  */
67  inline
68  void setFreq( int frequency)
69  {
70  step_size = ((((uint32_t)((PHASOR_MAX_VALUE_UL>>8)+1))/(UPDATE_RATE))*frequency)<<8;
71  }
72 
73 
74  /** Set the Phasor frequency with a float.
75  @param frequency is how many times per second to count from
76  0 to the maximum uint32_t value 4294967295.
77  */
78  inline
79  void setFreq(float frequency)
80  { // 1 us - using float doesn't seem to incur measurable overhead with the oscilloscope
81  step_size = (uint32_t)(((float)PHASOR_MAX_VALUE_UL/UPDATE_RATE)*frequency);
82  }
83 
84  /** phaseIncFromFreq() and setPhaseInc() are for saving processor time when sliding between frequencies.
85  Instead of recalculating the phase increment for each frequency in between, you
86  can just calculate the phase increment for each end frequency with
87  phaseIncFromFreq(), then use a Line to interpolate on the fly and use
88  setPhaseInc() to set the phase increment at each step. (Note: I should really
89  profile this with the oscilloscope to see if it's worth the extra confusion!)
90  @param frequency for which you want to calculate a phase increment value.
91  @return the phase increment value which will produce a given frequency.
92  */
93  inline
95  {
96  return ((((uint32_t)((PHASOR_MAX_VALUE_UL>>8)+1))/(UPDATE_RATE))*frequency)<<8;
97  }
98 
99 
100  /** Set a specific phase increment. See phaseIncFromFreq().
101  @param stepsize a phase increment value as calculated by phaseIncFromFreq().
102  */
103  inline
104  void setPhaseInc(uint32_t stepsize)
105  {
106  step_size = stepsize;
107  }
108 
109 };
110 
111 /**
112 @example 06.Synthesis/PWM_Phasing/PWM_Phasing.ino
113 This example demonstrates the Phasor class.
114 */
115 
116 #endif /* PHASOR_H_ */