M16/Mic.h at main · algomusic/M16 · GitHub

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
/*
 * Mic.h
 *
 * An I2S audio input class, particularly focused on I2S MEMS microphones.
 *
 * by Andrew R. Brown 2021
 *
 * Based on the Mozzi audio library by Tim Barrass 2012
 *
 * This file is part of the M16 audio library. Relies on M16.h
 *
 * M16 is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.
 */

#ifndef MIC_H_
#define MIC_H_

class Mic {
  public:
    /** Constructor
    * Start a new i2s input stream.
    */
    Mic() {}

    /**
    * Get the next left samples from the I2S audio input buffer
    */
    inline
    int16_t nextLeft() {
      if (mBufIndex == 0) {
        readMic();
      }
      int16_t val = inputBuf[mBufIndex * 2];
      mBufIndex++;
      if (mBufIndex >= samples_read/2) {
        mBufIndex = 0;
      }
      return val;
    }

    /**
    * Get the next left samples from the I2S audio input buffer
    */
    inline
    int16_t nextRight() {
      if (mBufIndex == 0) {
        readMic();
      }
      int16_t val = inputBuf[mBufIndex * 2 + 1];
      mBufIndex++;
      if (mBufIndex >= samples_read/2) {
        mBufIndex = 0;
      }
      return val;
    }


  private:
    int samples_read = 0;
    int micGain = 32; // 0 - 64
    static const int16_t bufferLen = 256; // buffer size in samples
    uint16_t inputBuf[bufferLen];
    int mBufIndex = 0;

    #if IS_ESP8266()
      void readMic() {
        // Mic class not yet implemented for ESP8266
      }
    #elif IS_ESP32()
      inline
      void readMic() {
        // Use new ESP32 I2S API (rx_handle defined in M16.h)
        extern i2s_chan_handle_t rx_handle;
        size_t bytesIn = 0;
        esp_err_t result = i2s_channel_read(rx_handle, inputBuf, bufferLen * sizeof(uint16_t), &bytesIn, portMAX_DELAY);
        if (result == ESP_OK && bytesIn > 0) {
          samples_read = bytesIn / 2; // stereo 16 bit samples
        }
      }
    #elif IS_RP2040()
      inline
      void readMic() {
        // Pico uses separate I2S input instance (i2sIn from M16.h)
        // Requires audioInputStart() to be called in setup()
        extern I2S i2sIn;
        extern volatile bool picoInputEnabled;

        if (!picoInputEnabled) {
          samples_read = 0;
          return;
        }

        // Read available samples from I2S input
        int available = i2sIn.available();
        if (available <= 0) {
          samples_read = 0;
          return;
        }

        // Read up to bufferLen/2 stereo samples (each sample is 32-bit containing L+R)
        int samplesToRead = min(available, (int)(bufferLen / 2));
        samples_read = 0;

        for (int i = 0; i < samplesToRead; i++) {
          int32_t sample32 = i2sIn.read();
          // Split 32-bit sample into left (high 16 bits) and right (low 16 bits)
          inputBuf[samples_read * 2] = (int16_t)(sample32 >> 16);       // Left channel
          inputBuf[samples_read * 2 + 1] = (int16_t)(sample32 & 0xFFFF); // Right channel
          samples_read++;
        }
        samples_read *= 2;  // Convert to total samples (L+R)
      }
    #endif
};

#endif /* MIC_H_ */