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Published © GPL3+

Wake word detection

We deploy TinyML project on Arduino Nano 33 BLE to detect word 'Yes' or 'No'.

IntermediateFull instructions provided6 hours992
Wake word detection

Things used in this project

Hardware components

Arduino Nano 33 BLE Sense
Arduino Nano 33 BLE Sense
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Software apps and online services

Arduino IDE
Arduino IDE

Hand tools and fabrication machines

TensorFlow Lite
TensorFlow Lite

Story

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Schematics

schematics_J1Kk6BDQsP.jpg

Code

micro_features_micro_model_settings.cpp

C/C++
/* Copyright 2018 The TensorFlow Authors. All Rights Reserved.

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.
==============================================================================*/

#include "micro_features_micro_model_settings.h"

const char* kCategoryLabels[kCategoryCount] = {
    "silence",
    "unknown",
    "yes",
    "no",
};

micro_features_no_micro_features_data.cpp

C/C++
/* Copyright 2019 The TensorFlow Authors. All Rights Reserved.

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.
==============================================================================*/

#include "micro_features_no_micro_features_data.h"

/* File automatically created by
 * tensorflow/examples/speech_commands/wav_to_features.py \
 * --sample_rate=16000 \
 * --clip_duration_ms=1000 \
 * --window_size_ms=30 \
 * --window_stride_ms=20 \
 * --feature_bin_count=40 \
 * --quantize=1 \
 * --preprocess="micro" \
 * --input_wav="speech_commands_test_set_v0.02/no/f9643d42_nohash_4.wav" \
 * --output_c_file="/tmp/no_micro_features_data.cc" \
 */

const int g_no_micro_f9643d42_nohash_4_width = 40;
const int g_no_micro_f9643d42_nohash_4_height = 49;
const unsigned char g_no_micro_f9643d42_nohash_4_data[] = {
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    221, 191, 215, 194, 211, 0,   156, 147, 182, 178, 208, 163, 190, 157, 208,
    200, 195, 164, 179, 154, 181, 150, 143, 99,  132, 137, 185, 143, 163, 85,
    51,  107, 132, 134, 164, 127, 167, 159, 175, 141, 216, 195, 223, 211, 238,
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    0,   0,   0,   0,   0,   0,   0,   0,   0,   0,
};

micro_features_yes_micro_features_data.cpp

C/C++
/* Copyright 2019 The TensorFlow Authors. All Rights Reserved.

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.
==============================================================================*/

#include "micro_features_yes_micro_features_data.h"

/* File automatically created by
 * tensorflow/examples/speech_commands/wav_to_features.py \
 * --sample_rate=16000 \
 * --clip_duration_ms=1000 \
 * --window_size_ms=30 \
 * --window_stride_ms=20 \
 * --feature_bin_count=40 \
 * --quantize=1 \
 * --preprocess="micro" \
 * --input_wav="speech_commands_test_set_v0.02/yes/f2e59fea_nohash_1.wav" \
 * --output_c_file="yes_micro_features_data.cc" \
 */

const int g_yes_micro_f2e59fea_nohash_1_width = 40;
const int g_yes_micro_f2e59fea_nohash_1_height = 49;
const unsigned char g_yes_micro_f2e59fea_nohash_1_data[] = {
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    143, 187, 165, 186, 149, 185, 141, 192, 181, 202, 123, 170, 143, 144, 78,
    149, 0,   208, 182, 170, 78,  170, 0,   117, 51,  156, 99,  195, 170, 200,
    130, 152, 68,  175, 141, 173, 134, 194, 132, 189, 164, 198, 134, 173, 117,
    171, 149, 183, 181, 185, 99,  153, 117, 125, 0,   166, 0,   173, 117, 144,
    0,   117, 102, 188, 120, 193, 166, 197, 68,  163, 119, 169, 99,  134, 0,
    162, 0,   164, 68,  171, 116, 126, 0,   120, 68,  68,  0,   105, 0,   159,
    95,  150, 51,  90,  85,  0,   0,   131, 0,   105, 0,   145, 51,  170, 51,
    120, 0,   107, 0,   145, 85,  160, 0,   85,  0,   0,   51,  149, 0,   78,
    0,   0,   0,   0,   0,   0,   0,   90,  0,   112, 0,   78,  102, 122, 0,
    0,   0,   0,   0,   105, 0,   0,   0,   0,   0,   0,   0,   0,   0,   112,
    0,   164, 120, 143, 0,   0,   0,   0,   0,   51,  0,   90,  0,   78,  0,
    0,   0,   0,   0,   110, 0,   139, 0,   112, 51,  0,   0,   0,   0,   0,
    0,   0,   0,   0,   0,   0,   0,   102, 0,   0,   0,   0,   0,   0,   0,
    0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   107,
    0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,
    0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,
    0,   0,   0,   0,   0,   0,   0,   0,   0,   78,  0,   51,  0,   0,   0,
    0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,
    0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,
    0,   0,   0,   0,   51,  0,   0,   0,   0,   0,   0,   0,   0,   0,   0,
    0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,
    0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,
    0,   0,   0,   0,   0,   127, 110, 133, 0,   167, 0,   0,   0,   0,   0,
    0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   132, 0,   190,
    194, 202, 0,   197, 187, 161, 0,   0,   0,   0,   0,   0,   0,   0,   0,
    214, 213, 223, 203, 218, 189, 200, 122, 78,  0,   0,   0,   0,   0,   0,
    0,   0,   0,   0,   0,   191, 210, 231, 197, 226, 217, 238, 216, 236, 207,
    199, 0,   0,   0,   0,   0,   107, 122, 155, 160, 214, 215, 236, 202, 235,
    203, 225, 191, 203, 188, 199, 194, 212, 127, 51,  0,   174, 188, 219, 196,
    228, 221, 240, 207, 235, 220, 241, 219, 237, 207, 212, 142, 95,  0,   139,
    78,  162, 177, 197, 183, 211, 199, 235, 208, 238, 215, 227, 207, 211, 201,
    224, 213, 226, 192, 213, 170, 223, 205, 234, 221, 245, 225, 242, 220, 245,
    221, 239, 221, 238, 213, 226, 180, 159, 112, 176, 159, 208, 202, 213, 191,
    205, 191, 225, 197, 238, 219, 224, 201, 227, 200, 221, 201, 225, 203, 212,
    195, 229, 210, 228, 210, 239, 216, 226, 212, 233, 205, 225, 200, 229, 207,
    222, 151, 147, 119, 179, 185, 230, 218, 223, 192, 202, 136, 205, 177, 223,
    204, 228, 215, 232, 209, 221, 189, 221, 205, 209, 200, 226, 209, 229, 205,
    235, 192, 209, 198, 228, 190, 206, 185, 207, 187, 214, 175, 177, 184, 220,
    195, 214, 207, 230, 184, 205, 159, 208, 184, 189, 169, 224, 213, 219, 199,
    229, 203, 216, 205, 222, 204, 224, 206, 231, 208, 231, 176, 197, 184, 216,
    193, 211, 139, 212, 195, 231, 164, 166, 195, 217, 182, 208, 190, 217, 179,
    205, 68,  182, 119, 195, 168, 182, 136, 204, 179, 193, 158, 182, 140, 188,
    154, 197, 169, 190, 99,  184, 0,   125, 0,   131, 0,   99,  68,  179, 85,
    190, 184, 213, 203, 223, 202, 212, 190, 209, 138, 178, 0,   159, 51,  128,
    51,  105, 0,   139, 51,  179, 125, 185, 114, 171, 128, 175, 132, 181, 174,
    155, 0,   0,   0,   90,  0,   125, 0,   176, 188, 227, 217, 244, 215, 234,
    221, 239, 192, 224, 210, 0,   0,   134, 0,   51,  0,   105, 0,   105, 0,
    143, 90,  192, 119, 175, 147, 141, 51,  184, 110, 85,  0,   0,   0,   0,
    0,   0,   0,   151, 139, 201, 203, 232, 203, 226, 208, 236, 206, 230, 212,
    0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   169, 0,   119,
    0,   78,  0,   0,   0,   0,   0,   0,   0,   0,   0,   68,  0,   0,   133,
    200, 180, 220, 197, 228, 201, 221, 184, 213, 193, 110, 0,   0,   0,   0,
    0,   0,   0,   0,   0,   78,  0,   164, 0,   0,   0,   0,   0,   107, 0,
    0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   150, 164, 202, 182, 224,
    197, 211, 179, 212, 193, 134, 0,   0,   0,   0,   0,   0,   0,   0,   0,
    85,  0,   150, 0,   85,  0,   95,  0,   0,   0,   0,   0,   0,   0,   0,
    0,   0,   0,   0,   0,   102, 90,  193, 160, 203, 164, 200, 178, 205, 174,
    116, 0,   0,   0,   0,   0,   0,   0,   0,   0,   120, 114, 123, 0,   114,
    0,   145, 68,  0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,
    102, 68,  199, 170, 195, 180, 208, 176, 200, 164, 0,   0,   0,   0,   0,
    0,   0,   0,   0,   0,   0,   0,   110, 0,   0,   0,   0,   0,   0,   0,
    0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   142, 102, 172, 110, 186,
    167, 185, 147, 189, 154, 0,   0,   0,   0,   0,   0,   0,   0,   0,   0,
    0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,
    0,   0,   0,   0,   0,   0,   0,   177, 0,   158, 136, 197, 155, 189, 166,
    0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,
    0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,
    85,  0,   155, 90,  175, 117, 175, 138, 202, 165, 0,   0,   0,   0,   0,
    0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,
    0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   51,  0,   139,
    0,   120, 68,  51,  123, 0,   0,   0,   0,   0,   0,   0,   0,   0,   0,
    0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,
    0,   0,   0,   0,   0,   0,   0,   0,   0,   119, 0,   78,  0,   0,   0,
    0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,
    0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,
    0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,
    0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,
    0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,
    0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,
    0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,
    0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,
    0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,
    0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,
    0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,
    0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,
    0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,
    0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,
    0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,
    0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,
    0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,
    0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,   0,
    0,   0,   0,   0,   0,   0,   0,   0,   0,   0,
};

recognize_commands.cpp

C/C++
/* Copyright 2017 The TensorFlow Authors. All Rights Reserved.

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.
==============================================================================*/

#include "recognize_commands.h"

#include <limits>

RecognizeCommands::RecognizeCommands(tflite::ErrorReporter* error_reporter,
                                     int32_t average_window_duration_ms,
                                     uint8_t detection_threshold,
                                     int32_t suppression_ms,
                                     int32_t minimum_count)
    : error_reporter_(error_reporter),
      average_window_duration_ms_(average_window_duration_ms),
      detection_threshold_(detection_threshold),
      suppression_ms_(suppression_ms),
      minimum_count_(minimum_count),
      previous_results_(error_reporter) {
  previous_top_label_ = "silence";
  previous_top_label_time_ = std::numeric_limits<int32_t>::min();
}

TfLiteStatus RecognizeCommands::ProcessLatestResults(
    const TfLiteTensor* latest_results, const int32_t current_time_ms,
    const char** found_command, uint8_t* score, bool* is_new_command) {
  if ((latest_results->dims->size != 2) ||
      (latest_results->dims->data[0] != 1) ||
      (latest_results->dims->data[1] != kCategoryCount)) {
    error_reporter_->Report(
        "The results for recognition should contain %d elements, but there are "
        "%d in an %d-dimensional shape",
        kCategoryCount, latest_results->dims->data[1],
        latest_results->dims->size);
    return kTfLiteError;
  }

  if (latest_results->type != kTfLiteUInt8) {
    error_reporter_->Report(
        "The results for recognition should be uint8 elements, but are %d",
        latest_results->type);
    return kTfLiteError;
  }

  if ((!previous_results_.empty()) &&
      (current_time_ms < previous_results_.front().time_)) {
    error_reporter_->Report(
        "Results must be fed in increasing time order, but received a "
        "timestamp of %d that was earlier than the previous one of %d",
        current_time_ms, previous_results_.front().time_);
    return kTfLiteError;
  }

  // Add the latest results to the head of the queue.
  previous_results_.push_back({current_time_ms, latest_results->data.uint8});

  // Prune any earlier results that are too old for the averaging window.
  const int64_t time_limit = current_time_ms - average_window_duration_ms_;
  while ((!previous_results_.empty()) &&
         previous_results_.front().time_ < time_limit) {
    previous_results_.pop_front();
  }

  // If there are too few results, assume the result will be unreliable and
  // bail.
  const int64_t how_many_results = previous_results_.size();
  const int64_t earliest_time = previous_results_.front().time_;
  const int64_t samples_duration = current_time_ms - earliest_time;
  if ((how_many_results < minimum_count_) ||
      (samples_duration < (average_window_duration_ms_ / 4))) {
    *found_command = previous_top_label_;
    *score = 0;
    *is_new_command = false;
    return kTfLiteOk;
  }

  // Calculate the average score across all the results in the window.
  int32_t average_scores[kCategoryCount];
  for (int offset = 0; offset < previous_results_.size(); ++offset) {
    PreviousResultsQueue::Result previous_result =
        previous_results_.from_front(offset);
    const uint8_t* scores = previous_result.scores_;
    for (int i = 0; i < kCategoryCount; ++i) {
      if (offset == 0) {
        average_scores[i] = scores[i];
      } else {
        average_scores[i] += scores[i];
      }
    }
  }
  for (int i = 0; i < kCategoryCount; ++i) {
    average_scores[i] /= how_many_results;
  }

  // Find the current highest scoring category.
  int current_top_index = 0;
  int32_t current_top_score = 0;
  for (int i = 0; i < kCategoryCount; ++i) {
    if (average_scores[i] > current_top_score) {
      current_top_score = average_scores[i];
      current_top_index = i;
    }
  }
  const char* current_top_label = kCategoryLabels[current_top_index];

  // If we've recently had another label trigger, assume one that occurs too
  // soon afterwards is a bad result.
  int64_t time_since_last_top;
  if ((previous_top_label_ == kCategoryLabels[0]) ||
      (previous_top_label_time_ == std::numeric_limits<int32_t>::min())) {
    time_since_last_top = std::numeric_limits<int32_t>::max();
  } else {
    time_since_last_top = current_time_ms - previous_top_label_time_;
  }
  if ((current_top_score > detection_threshold_) &&
      ((current_top_label != previous_top_label_) ||
       (time_since_last_top > suppression_ms_))) {
    previous_top_label_ = current_top_label;
    previous_top_label_time_ = current_time_ms;
    *is_new_command = true;
  } else {
    *is_new_command = false;
  }
  *found_command = current_top_label;
  *score = current_top_score;

  return kTfLiteOk;
}

micro_speech.ino

C/C++
/* Copyright 2018 The TensorFlow Authors. All Rights Reserved.

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.
==============================================================================*/

#include <TensorFlowLite.h>

#include "main_functions.h"

#include "audio_provider.h"
#include "command_responder.h"
#include "feature_provider.h"
#include "micro_features_micro_model_settings.h"
#include "micro_features_tiny_conv_micro_features_model_data.h"
#include "recognize_commands.h"
#include "tensorflow/lite/experimental/micro/kernels/micro_ops.h"
#include "tensorflow/lite/experimental/micro/micro_error_reporter.h"
#include "tensorflow/lite/experimental/micro/micro_interpreter.h"
#include "tensorflow/lite/experimental/micro/micro_mutable_op_resolver.h"
#include "tensorflow/lite/schema/schema_generated.h"
#include "tensorflow/lite/version.h"

// Globals, used for compatibility with Arduino-style sketches.
namespace {
tflite::ErrorReporter* error_reporter = nullptr;
const tflite::Model* model = nullptr;
tflite::MicroInterpreter* interpreter = nullptr;
TfLiteTensor* model_input = nullptr;
FeatureProvider* feature_provider = nullptr;
RecognizeCommands* recognizer = nullptr;
int32_t previous_time = 0;

// Create an area of memory to use for input, output, and intermediate arrays.
// The size of this will depend on the model you're using, and may need to be
// determined by experimentation.
constexpr int kTensorArenaSize = 10 * 1024;
uint8_t tensor_arena[kTensorArenaSize];
}  // namespace

// The name of this function is important for Arduino compatibility.
void setup() {
  // Set up logging. Google style is to avoid globals or statics because of
  // lifetime uncertainty, but since this has a trivial destructor it's okay.
  // NOLINTNEXTLINE(runtime-global-variables)
  static tflite::MicroErrorReporter micro_error_reporter;
  error_reporter = &micro_error_reporter;

  // Map the model into a usable data structure. This doesn't involve any
  // copying or parsing, it's a very lightweight operation.
  model = tflite::GetModel(g_tiny_conv_micro_features_model_data);
  if (model->version() != TFLITE_SCHEMA_VERSION) {
    error_reporter->Report(
        "Model provided is schema version %d not equal "
        "to supported version %d.",
        model->version(), TFLITE_SCHEMA_VERSION);
    return;
  }

  // Pull in only the operation implementations we need.
  // This relies on a complete list of all the ops needed by this graph.
  // An easier approach is to just use the AllOpsResolver, but this will
  // incur some penalty in code space for op implementations that are not
  // needed by this graph.
  //
  // tflite::ops::micro::AllOpsResolver resolver;
  // NOLINTNEXTLINE(runtime-global-variables)
  static tflite::MicroMutableOpResolver micro_mutable_op_resolver;
  micro_mutable_op_resolver.AddBuiltin(
      tflite::BuiltinOperator_DEPTHWISE_CONV_2D,
      tflite::ops::micro::Register_DEPTHWISE_CONV_2D());
  micro_mutable_op_resolver.AddBuiltin(
      tflite::BuiltinOperator_FULLY_CONNECTED,
      tflite::ops::micro::Register_FULLY_CONNECTED());
  micro_mutable_op_resolver.AddBuiltin(tflite::BuiltinOperator_SOFTMAX,
                                       tflite::ops::micro::Register_SOFTMAX());

  // Build an interpreter to run the model with.
  static tflite::MicroInterpreter static_interpreter(
      model, micro_mutable_op_resolver, tensor_arena, kTensorArenaSize,
      error_reporter);
  interpreter = &static_interpreter;

  // Allocate memory from the tensor_arena for the model's tensors.
  TfLiteStatus allocate_status = interpreter->AllocateTensors();
  if (allocate_status != kTfLiteOk) {
    error_reporter->Report("AllocateTensors() failed");
    return;
  }

  // Get information about the memory area to use for the model's input.
  model_input = interpreter->input(0);
  if ((model_input->dims->size != 4) || (model_input->dims->data[0] != 1) ||
      (model_input->dims->data[1] != kFeatureSliceCount) ||
      (model_input->dims->data[2] != kFeatureSliceSize) ||
      (model_input->type != kTfLiteUInt8)) {
    error_reporter->Report("Bad input tensor parameters in model");
    return;
  }

  // Prepare to access the audio spectrograms from a microphone or other source
  // that will provide the inputs to the neural network.
  // NOLINTNEXTLINE(runtime-global-variables)
  static FeatureProvider static_feature_provider(kFeatureElementCount,
                                                 model_input->data.uint8);
  feature_provider = &static_feature_provider;

  static RecognizeCommands static_recognizer(error_reporter);
  recognizer = &static_recognizer;

  previous_time = 0;
}

// The name of this function is important for Arduino compatibility.
void loop() {
  // Fetch the spectrogram for the current time.
  const int32_t current_time = LatestAudioTimestamp();
  int how_many_new_slices = 0;
  TfLiteStatus feature_status = feature_provider->PopulateFeatureData(
      error_reporter, previous_time, current_time, &how_many_new_slices);
  if (feature_status != kTfLiteOk) {
    error_reporter->Report("Feature generation failed");
    return;
  }
  previous_time = current_time;
  // If no new audio samples have been received since last time, don't bother
  // running the network model.
  if (how_many_new_slices == 0) {
    return;
  }

  // Run the model on the spectrogram input and make sure it succeeds.
  TfLiteStatus invoke_status = interpreter->Invoke();
  if (invoke_status != kTfLiteOk) {
    error_reporter->Report("Invoke failed");
    return;
  }

  // Obtain a pointer to the output tensor
  TfLiteTensor* output = interpreter->output(0);
  // Determine whether a command was recognized based on the output of inference
  const char* found_command = nullptr;
  uint8_t score = 0;
  bool is_new_command = false;
  TfLiteStatus process_status = recognizer->ProcessLatestResults(
      output, current_time, &found_command, &score, &is_new_command);
  if (process_status != kTfLiteOk) {
    error_reporter->Report("RecognizeCommands::ProcessLatestResults() failed");
    return;
  }
  // Do something based on the recognized command. The default implementation
  // just prints to the error console, but you should replace this with your
  // own function for a real application.
  RespondToCommand(error_reporter, current_time, found_command, score,
                   is_new_command);
}

arduino_audio_provider.cpp

C/C++
/* Copyright 2018 The TensorFlow Authors. All Rights Reserved.

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.
==============================================================================*/

/* Copyright 2018 The TensorFlow Authors. All Rights Reserved.

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.
==============================================================================*/

#include "audio_provider.h"

#include "PDM.h"
#include "micro_features_micro_model_settings.h"

namespace {
bool g_is_audio_initialized = false;
// An internal buffer able to fit 16x our sample size
constexpr int kAudioCaptureBufferSize = DEFAULT_PDM_BUFFER_SIZE * 16;
int16_t g_audio_capture_buffer[kAudioCaptureBufferSize];
// A buffer that holds our output
int16_t g_audio_output_buffer[kMaxAudioSampleSize];
// Mark as volatile so we can check in a while loop to see if
// any samples have arrived yet.
volatile int32_t g_latest_audio_timestamp = 0;
}  // namespace

void CaptureSamples() {
  // This is how many bytes of new data we have each time this is called
  const int number_of_samples = DEFAULT_PDM_BUFFER_SIZE;
  // Calculate what timestamp the last audio sample represents
  const int32_t time_in_ms =
      g_latest_audio_timestamp +
      (number_of_samples / (kAudioSampleFrequency / 1000));
  // Determine the index, in the history of all samples, of the last sample
  const int32_t start_sample_offset =
      g_latest_audio_timestamp * (kAudioSampleFrequency / 1000);
  // Determine the index of this sample in our ring buffer
  const int capture_index = start_sample_offset % kAudioCaptureBufferSize;
  // Read the data to the correct place in our buffer
  PDM.read(g_audio_capture_buffer + capture_index, DEFAULT_PDM_BUFFER_SIZE);
  // This is how we let the outside world know that new audio data has arrived.
  g_latest_audio_timestamp = time_in_ms;
}

TfLiteStatus InitAudioRecording(tflite::ErrorReporter* error_reporter) {
  // Hook up the callback that will be called with each sample
  PDM.onReceive(CaptureSamples);
  // Start listening for audio: MONO @ 16KHz with gain at 20
  PDM.begin(1, kAudioSampleFrequency);
  PDM.setGain(20);
  // Block until we have our first audio sample
  while (!g_latest_audio_timestamp) {
  }

  return kTfLiteOk;
}

TfLiteStatus GetAudioSamples(tflite::ErrorReporter* error_reporter,
                             int start_ms, int duration_ms,
                             int* audio_samples_size, int16_t** audio_samples) {
  // Set everything up to start receiving audio
  if (!g_is_audio_initialized) {
    TfLiteStatus init_status = InitAudioRecording(error_reporter);
    if (init_status != kTfLiteOk) {
      return init_status;
    }
    g_is_audio_initialized = true;
  }
  // This next part should only be called when the main thread notices that the
  // latest audio sample data timestamp has changed, so that there's new data
  // in the capture ring buffer. The ring buffer will eventually wrap around and
  // overwrite the data, but the assumption is that the main thread is checking
  // often enough and the buffer is large enough that this call will be made
  // before that happens.

  // Determine the index, in the history of all samples, of the first
  // sample we want
  const int start_offset = start_ms * (kAudioSampleFrequency / 1000);
  // Determine how many samples we want in total
  const int duration_sample_count =
      duration_ms * (kAudioSampleFrequency / 1000);
  for (int i = 0; i < duration_sample_count; ++i) {
    // For each sample, transform its index in the history of all samples into
    // its index in g_audio_capture_buffer
    const int capture_index = (start_offset + i) % kAudioCaptureBufferSize;
    // Write the sample to the output buffer
    g_audio_output_buffer[i] = g_audio_capture_buffer[capture_index];
  }

  // Set pointers to provide access to the audio
  *audio_samples_size = kMaxAudioSampleSize;
  *audio_samples = g_audio_output_buffer;

  return kTfLiteOk;
}

int32_t LatestAudioTimestamp() { return g_latest_audio_timestamp; }

arduino_command_responder.cpp

C/C++
/* Copyright 2019 The TensorFlow Authors. All Rights Reserved.

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.
==============================================================================*/

#include "command_responder.h"

#include "Arduino.h"

// Toggles the built-in LED every inference, and lights a colored LED depending
// on which word was detected.
void RespondToCommand(tflite::ErrorReporter* error_reporter,
                      int32_t current_time, const char* found_command,
                      uint8_t score, bool is_new_command) {
  static bool is_initialized = false;
  if (!is_initialized) {
    pinMode(LED_BUILTIN, OUTPUT);
    // Pins for the built-in RGB LEDs on the Arduino Nano 33 BLE Sense
    pinMode(LEDR, OUTPUT);
    pinMode(LEDG, OUTPUT);
    pinMode(LEDB, OUTPUT);
    is_initialized = true;
  }
  static int32_t last_command_time = 0;
  static int count = 0;
  static int certainty = 220;

  if (is_new_command) {
    error_reporter->Report("Heard %s (%d) @%dms", found_command, score,
                           current_time);
    // If we hear a command, light up the appropriate LED.
    // Note: The RGB LEDs on the Arduino Nano 33 BLE
    // Sense are on when the pin is LOW, off when HIGH.
    if (found_command[0] == 'y') {
      last_command_time = current_time;
      digitalWrite(LEDG, LOW);  // Green for yes
      delay(100);
      digitalWrite(LEDG, HIGH);
      delay(100);
      digitalWrite(LEDG, LOW);  
      delay(100);
      digitalWrite(LEDG, HIGH);
      delay(100);
      digitalWrite(LEDG, LOW); 
    }

    if (found_command[0] == 'n') {
      last_command_time = current_time;
      digitalWrite(LEDR, LOW);  // Red for no
    }

    if (found_command[0] == 'u') {
      last_command_time = current_time;
      digitalWrite(LEDB, LOW);  // Blue for unknown
    }
  }

  // If last_command_time is non-zero but was >3 seconds ago, zero it
  // and switch off the LED.
  if (last_command_time != 0) {
    if (last_command_time < (current_time - 3000)) {
      last_command_time = 0;
      digitalWrite(LED_BUILTIN, LOW);
      digitalWrite(LEDR, HIGH);
      digitalWrite(LEDG, HIGH);
      digitalWrite(LEDB, HIGH);
    }
    // If it is non-zero but <3 seconds ago, do nothing.
    return;
  }

  // Otherwise, toggle the LED every time an inference is performed.
  ++count;
  if (count & 1) {
    digitalWrite(LED_BUILTIN, HIGH);
  } else {
    digitalWrite(LED_BUILTIN, LOW);
  }
}

arduino_main.cpp

C/C++
/* Copyright 2019 The TensorFlow Authors. All Rights Reserved.

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.
==============================================================================*/

#include "main_functions.h"

// Arduino automatically calls the setup() and loop() functions in a sketch, so
// where other systems need their own main routine in this file, it can be left
// empty.

audio_provider.h

C/C++
/* Copyright 2018 The TensorFlow Authors. All Rights Reserved.

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 TENSORFLOW_LITE_EXPERIMENTAL_MICRO_EXAMPLES_MICRO_SPEECH_AUDIO_PROVIDER_H_
#define TENSORFLOW_LITE_EXPERIMENTAL_MICRO_EXAMPLES_MICRO_SPEECH_AUDIO_PROVIDER_H_

#include "tensorflow/lite/c/c_api_internal.h"
#include "tensorflow/lite/experimental/micro/micro_error_reporter.h"

// This is an abstraction around an audio source like a microphone, and is
// expected to return 16-bit PCM sample data for a given point in time. The
// sample data itself should be used as quickly as possible by the caller, since
// to allow memory optimizations there are no guarantees that the samples won't
// be overwritten by new data in the future. In practice, implementations should
// ensure that there's a reasonable time allowed for clients to access the data
// before any reuse.
// The reference implementation can have no platform-specific dependencies, so
// it just returns an array filled with zeros. For real applications, you should
// ensure there's a specialized implementation that accesses hardware APIs.
TfLiteStatus GetAudioSamples(tflite::ErrorReporter* error_reporter,
                             int start_ms, int duration_ms,
                             int* audio_samples_size, int16_t** audio_samples);

// Returns the time that audio data was last captured in milliseconds. There's
// no contract about what time zero represents, the accuracy, or the granularity
// of the result. Subsequent calls will generally not return a lower value, but
// even that's not guaranteed if there's an overflow wraparound.
// The reference implementation of this function just returns a constantly
// incrementing value for each call, since it would need a non-portable platform
// call to access time information. For real applications, you'll need to write
// your own platform-specific implementation.
int32_t LatestAudioTimestamp();

#endif  // TENSORFLOW_LITE_EXPERIMENTAL_MICRO_EXAMPLES_MICRO_SPEECH_AUDIO_PROVIDER_H_

command_responder.h

C/C++
/* Copyright 2019 The TensorFlow Authors. All Rights Reserved.

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.
==============================================================================*/

// Provides an interface to take an action based on an audio command.

#ifndef TENSORFLOW_LITE_EXPERIMENTAL_MICRO_EXAMPLES_MICRO_SPEECH_COMMAND_RESPONDER_H_
#define TENSORFLOW_LITE_EXPERIMENTAL_MICRO_EXAMPLES_MICRO_SPEECH_COMMAND_RESPONDER_H_

#include "tensorflow/lite/c/c_api_internal.h"
#include "tensorflow/lite/experimental/micro/micro_error_reporter.h"

// Called every time the results of an audio recognition run are available. The
// human-readable name of any recognized command is in the `found_command`
// argument, `score` has the numerical confidence, and `is_new_command` is set
// if the previous command was different to this one.
void RespondToCommand(tflite::ErrorReporter* error_reporter,
                      int32_t current_time, const char* found_command,
                      uint8_t score, bool is_new_command);

#endif  // TENSORFLOW_LITE_EXPERIMENTAL_MICRO_EXAMPLES_MICRO_SPEECH_COMMAND_RESPONDER_H_

feature_provider.cpp

C/C++
/* Copyright 2018 The TensorFlow Authors. All Rights Reserved.

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.
==============================================================================*/

#include "feature_provider.h"

#include "audio_provider.h"
#include "micro_features_micro_features_generator.h"
#include "micro_features_micro_model_settings.h"

FeatureProvider::FeatureProvider(int feature_size, uint8_t* feature_data)
    : feature_size_(feature_size),
      feature_data_(feature_data),
      is_first_run_(true) {
  // Initialize the feature data to default values.
  for (int n = 0; n < feature_size_; ++n) {
    feature_data_[n] = 0;
  }
}

FeatureProvider::~FeatureProvider() {}

TfLiteStatus FeatureProvider::PopulateFeatureData(
    tflite::ErrorReporter* error_reporter, int32_t last_time_in_ms,
    int32_t time_in_ms, int* how_many_new_slices) {
  if (feature_size_ != kFeatureElementCount) {
    error_reporter->Report("Requested feature_data_ size %d doesn't match %d",
                           feature_size_, kFeatureElementCount);
    return kTfLiteError;
  }

  // Quantize the time into steps as long as each window stride, so we can
  // figure out which audio data we need to fetch.
  const int last_step = (last_time_in_ms / kFeatureSliceStrideMs);
  const int current_step = (time_in_ms / kFeatureSliceStrideMs);

  int slices_needed = current_step - last_step;
  // If this is the first call, make sure we don't use any cached information.
  if (is_first_run_) {
    TfLiteStatus init_status = InitializeMicroFeatures(error_reporter);
    if (init_status != kTfLiteOk) {
      return init_status;
    }
    is_first_run_ = false;
    slices_needed = kFeatureSliceCount;
  }
  if (slices_needed > kFeatureSliceCount) {
    slices_needed = kFeatureSliceCount;
  }
  *how_many_new_slices = slices_needed;

  const int slices_to_keep = kFeatureSliceCount - slices_needed;
  const int slices_to_drop = kFeatureSliceCount - slices_to_keep;
  // If we can avoid recalculating some slices, just move the existing data
  // up in the spectrogram, to perform something like this:
  // last time = 80ms          current time = 120ms
  // +-----------+             +-----------+
  // | data@20ms |         --> | data@60ms |
  // +-----------+       --    +-----------+
  // | data@40ms |     --  --> | data@80ms |
  // +-----------+   --  --    +-----------+
  // | data@60ms | --  --      |  <empty>  |
  // +-----------+   --        +-----------+
  // | data@80ms | --          |  <empty>  |
  // +-----------+             +-----------+
  if (slices_to_keep > 0) {
    for (int dest_slice = 0; dest_slice < slices_to_keep; ++dest_slice) {
      uint8_t* dest_slice_data =
          feature_data_ + (dest_slice * kFeatureSliceSize);
      const int src_slice = dest_slice + slices_to_drop;
      const uint8_t* src_slice_data =
          feature_data_ + (src_slice * kFeatureSliceSize);
      for (int i = 0; i < kFeatureSliceSize; ++i) {
        dest_slice_data[i] = src_slice_data[i];
      }
    }
  }
  // Any slices that need to be filled in with feature data have their
  // appropriate audio data pulled, and features calculated for that slice.
  if (slices_needed > 0) {
    for (int new_slice = slices_to_keep; new_slice < kFeatureSliceCount;
         ++new_slice) {
      const int new_step = (current_step - kFeatureSliceCount + 1) + new_slice;
      const int32_t slice_start_ms = (new_step * kFeatureSliceStrideMs);
      int16_t* audio_samples = nullptr;
      int audio_samples_size = 0;
      // TODO(petewarden): Fix bug that leads to non-zero slice_start_ms
      GetAudioSamples(error_reporter, (slice_start_ms > 0 ? slice_start_ms : 0),
                      kFeatureSliceDurationMs, &audio_samples_size,
                      &audio_samples);
      if (audio_samples_size < kMaxAudioSampleSize) {
        error_reporter->Report("Audio data size %d too small, want %d",
                               audio_samples_size, kMaxAudioSampleSize);
        return kTfLiteError;
      }
      uint8_t* new_slice_data = feature_data_ + (new_slice * kFeatureSliceSize);
      size_t num_samples_read;
      TfLiteStatus generate_status = GenerateMicroFeatures(
          error_reporter, audio_samples, audio_samples_size, kFeatureSliceSize,
          new_slice_data, &num_samples_read);
      if (generate_status != kTfLiteOk) {
        return generate_status;
      }
    }
  }
  return kTfLiteOk;
}

main_functions.h

C/C++
/* Copyright 2019 The TensorFlow Authors. All Rights Reserved.

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 TENSORFLOW_LITE_EXPERIMENTAL_MICRO_EXAMPLES_MICRO_SPEECH_MAIN_FUNCTIONS_H_
#define TENSORFLOW_LITE_EXPERIMENTAL_MICRO_EXAMPLES_MICRO_SPEECH_MAIN_FUNCTIONS_H_

// Initializes all data needed for the example. The name is important, and needs
// to be setup() for Arduino compatibility.
void setup();

// Runs one iteration of data gathering and inference. This should be called
// repeatedly from the application code. The name needs to be loop() for Arduino
// compatibility.
void loop();

#endif  // TENSORFLOW_LITE_EXPERIMENTAL_MICRO_EXAMPLES_MICRO_SPEECH_MAIN_FUNCTIONS_H_

micro_features_micro_features_generator.cpp

C/C++
/* Copyright 2019 The TensorFlow Authors. All Rights Reserved.

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.
==============================================================================*/

#include "micro_features_micro_features_generator.h"

#include <cmath>
#include <cstring>

#include "micro_features_micro_model_settings.h"
#include "tensorflow/lite/experimental/microfrontend/lib/frontend.h"
#include "tensorflow/lite/experimental/microfrontend/lib/frontend_util.h"

// Configure FFT to output 16 bit fixed point.
#define FIXED_POINT 16

namespace {

FrontendState g_micro_features_state;
bool g_is_first_time = true;

}  // namespace

TfLiteStatus InitializeMicroFeatures(tflite::ErrorReporter* error_reporter) {
  FrontendConfig config;
  config.window.size_ms = kFeatureSliceDurationMs;
  config.window.step_size_ms = kFeatureSliceStrideMs;
  config.noise_reduction.smoothing_bits = 10;
  config.filterbank.num_channels = kFeatureSliceSize;
  config.filterbank.lower_band_limit = 125.0;
  config.filterbank.upper_band_limit = 7500.0;
  config.noise_reduction.smoothing_bits = 10;
  config.noise_reduction.even_smoothing = 0.025;
  config.noise_reduction.odd_smoothing = 0.06;
  config.noise_reduction.min_signal_remaining = 0.05;
  config.pcan_gain_control.enable_pcan = 1;
  config.pcan_gain_control.strength = 0.95;
  config.pcan_gain_control.offset = 80.0;
  config.pcan_gain_control.gain_bits = 21;
  config.log_scale.enable_log = 1;
  config.log_scale.scale_shift = 6;
  if (!FrontendPopulateState(&config, &g_micro_features_state,
                             kAudioSampleFrequency)) {
    error_reporter->Report("FrontendPopulateState() failed");
    return kTfLiteError;
  }
  g_is_first_time = true;
  return kTfLiteOk;
}

// This is not exposed in any header, and is only used for testing, to ensure
// that the state is correctly set up before generating results.
void SetMicroFeaturesNoiseEstimates(const uint32_t* estimate_presets) {
  for (int i = 0; i < g_micro_features_state.filterbank.num_channels; ++i) {
    g_micro_features_state.noise_reduction.estimate[i] = estimate_presets[i];
  }
}

TfLiteStatus GenerateMicroFeatures(tflite::ErrorReporter* error_reporter,
                                   const int16_t* input, int input_size,
                                   int output_size, uint8_t* output,
                                   size_t* num_samples_read) {
  const int16_t* frontend_input;
  if (g_is_first_time) {
    frontend_input = input;
    g_is_first_time = false;
  } else {
    frontend_input = input + 160;
  }
  FrontendOutput frontend_output = FrontendProcessSamples(
      &g_micro_features_state, frontend_input, input_size, num_samples_read);

  for (int i = 0; i < frontend_output.size; ++i) {
    // These scaling values are derived from those used in input_data.py in the
    // training pipeline.
    constexpr int32_t value_scale = (10 * 255);
    constexpr int32_t value_div = (256 * 26);
    int32_t value =
        ((frontend_output.values[i] * value_scale) + (value_div / 2)) /
        value_div;
    if (value < 0) {
      value = 0;
    }
    if (value > 255) {
      value = 255;
    }
    output[i] = value;
  }

  return kTfLiteOk;
}

Wake word detection

Code for word detection

Credits

Weijian Zhan
1 project • 2 followers
Jianxu Chen
1 project • 2 followers
Xiyuan He
1 project • 2 followers
Xuan Liu
0 projects • 1 follower

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