DIY Model Weight Update for Continuous AI Deployments

/**
 * Edge Impulse OTA updates.
 * Open the Serial Monitor and enter "ota"
 * to perform the update.
 * Enter "restore" to restore the original weights.
 * 
 * This project ships with a "dumb" model (default)
 * which can't predict anything. When you enter "ota",
 * a "smart" model is loaded and you will see it detects
 * the penguin in the input data.
 * 
 * When you enter "restore", the dumb model is loaded back
 * and the models makes no more predictions.
 */

#define WIFI_SSID "SSID"
#define WIFI_PASS "PASSWORD"
#define EI_API_KEY "ei_59e01e8cdef245c00a1e5f654f978f806ecebe5f2c58d68b"
#define EI_PROJECT_ID "508852"
#define OTA_SERVER "eloquentarduino.com"
#define OTA_PATH "/edgeimpulse-ota/serve/" EI_API_KEY "/" EI_PROJECT_ID ".bin"

#include <WiFi.h>
#include <fomo-dumb_inferencing.h>


signal_t input;
ei_impulse_result_t result;
WiFiClient http;

float penguin[] = {0x4c584d, 0x4c5750 ... 0x90f0d, 0x90f0d};


bool makeRequest();
void updateWeights(Stream& updateSource);
void restoreWeights();


void setup() {
  Serial.begin(115200);
  while (!Serial);
  delay(3000);
  Serial.println("Edge Impulse OTA over HTTP");

  // connect to WiFi
  WiFi.begin(WIFI_SSID, WIFI_PASS);
  
  while (WiFi.status() != WL_CONNECTED) {
    Serial.println("Attempting to connect to WiFi...");
    delay(2000);
  }
}


void loop() {  
  Serial.println("loop");
  String userInput = Serial.available() ? Serial.readStringUntil('\n') : "";


  // update / restore weights from user input
  if (userInput.startsWith("ota")) {
    if (makeRequest())
      updateWeights(http);
  }

  if (userInput.startsWith("restore")) {
    restoreWeights();
  }


  // run impulse
  if (numpy::signal_from_buffer(penguin, EI_CLASSIFIER_DSP_INPUT_FRAME_SIZE, &input) != 0) {
    Serial.println("numpy::signal_from_buffer failed");
    return;
  }

  if (run_classifier(&input, &result, false) != 0) {
    Serial.println("run_classifier failed");
    return;
  }


  // print results
  for (size_t ix = 0; ix < result.bounding_boxes_count; ix++) {
    auto bb = result.bounding_boxes[ix];

    if (bb.value > 0) {
        Serial.print(" > Found object ");
        Serial.print(bb.label);
        Serial.print(" at x, y = ");
        Serial.print(bb.x);
        Serial.print(", ");
        Serial.print(bb.y);
        Serial.print(" with confidence ");
        Serial.println(bb.value);
    }
  }

  delay(1000);
}


bool makeRequest() {
  // flush request, if necessary
  while (http.connected() && http.available())
    http.read();
    
  //http.stop();
  
  if (http.connect(OTA_SERVER, 80)) {
    Serial.println("connected to server");
    // Make a HTTP request:
    http.print("GET ");
    http.print(OTA_PATH);
    http.println(" HTTP/1.1");
    http.print("Host: ");
    http.println(OTA_SERVER);
    http.println("User-Agent: Arduino");
    http.println("Connection: close");
    http.println();
    delay(3000);

    size_t timeout = millis() + 10000L;
    String response("");

    while (millis() < timeout) {
      if (http.available()) {
        response += (char) http.read();

        // detect start of body
        if (response.endsWith("edgeimpulse")) {
          Serial.println("Response:");
          Serial.println(response);
          
          return true;
        }
      }
    }

    Serial.println("Got response, but cannot detect body");
    return false;
  }
  else {
    Serial.println("Can't connect to OTA server");
    return false;
  }
}


void updateWeights(Stream& updateSource) {
  Serial.println("Updating weights...");
  String updateError = ei_update_weights(updateSource);

  if (updateError != "") {
    Serial.print("Update error: ");
    Serial.println(updateError);
    restoreWeights();
  }
  else {
    Serial.println("Update ok!");
  }
}


void restoreWeights() {
  Serial.println("Restoring original weights...");

  String restoreError = ei_restore_weights();

  if (restoreError != "") {
    Serial.print("Restore error: ");
    Serial.println(restoreError);
  }
  else {
    Serial.println("Restore ok!");
  }
}