Nano 33 ble sense rev 2 Bluetooth connection

I am working on a fall detection system using the Arduino Nano 33 BLE Sense Rev 2 board. The goal is to detect falls using data from the BMI270 sensor, send a Bluetooth signal to a mobile app, and trigger an SMS when a fall is detected. My device is not connecting to the app. I tried a basic ble connection code then it connected but when i try with my code it is not connecting.

/* Edge Impulse ingestion SDK
 * Copyright (c) 2022 EdgeImpulse Inc.
 *
 * 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.
 *
 */

/* Includes ---------------------------------------------------------------- */
#include <Fall_detecting_inferencing.h>
#include <Arduino_BMI270_BMM150.h> //Click here to get the library: https://www.arduino.cc/reference/en/libraries/arduino_bmi270_bmm150/
#include <ArduinoBLE.h>

/* Constant defines -------------------------------------------------------- */
#define CONVERT_G_TO_MS2    9.80665f
#define MAX_ACCEPTED_RANGE  2.0f        // starting 03/2022, models are generated setting range to +-2, but this example use Arudino library which set range to +-4g. If you are using an older model, ignore this value and use 4.0f instead

/*
 ** NOTE: If you run into TFLite arena allocation issue.
 **
 ** This may be due to may dynamic memory fragmentation.
 ** Try defining "-DEI_CLASSIFIER_ALLOCATION_STATIC" in boards.local.txt (create
 ** if it doesn't exist) and copy this file to
 ** `<ARDUINO_CORE_INSTALL_PATH>/arduino/hardware/<mbed_core>/<core_version>/`.
 **
 ** See
 ** (https://support.arduino.cc/hc/en-us/articles/360012076960-Where-are-the-installed-cores-located-)
 ** to find where Arduino installs cores on your machine.
 **
 ** If the problem persists then there's not enough memory for this model and application.
 */

/* Private variables ------------------------------------------------------- */
static bool debug_nn = false; // Set this to true to see e.g. features generated from the raw signal
static uint32_t run_inference_every_ms = 200;
static rtos::Thread inference_thread(osPriorityLow);
static float buffer[EI_CLASSIFIER_DSP_INPUT_FRAME_SIZE] = { 0 };
static float inference_buffer[EI_CLASSIFIER_DSP_INPUT_FRAME_SIZE];

/* Forward declaration */
void run_inference_background();

//Blutooth service activating

BLEService fall_service("e267751a-ae76-11eb-8529-0242ac130003");
BLEIntCharacteristic fall("e267751b-ae76-11eb-8529-0242ac130003", BLERead | BLENotify); 





/**
* @brief      Arduino setup function
*/

void setup()
{
    // put your setup code here, to run once:
    Serial.begin(115200);
    if (!BLE.begin()) {
        Serial.println("starting BLE failed!");
        while (1);
    }

    BLE.setLocalName("Fall_Detecter");
    BLE.setAdvertisedService(fall_service);
    fall_service.addCharacteristic(fall);
    BLE.addService(fall_service);
    BLE.advertise();
    Serial.println("Bluetooth device active, waiting for connections...");
    // comment out the below line to cancel the wait for USB connection (needed for native USB)
    while (!Serial);
    Serial.println("Edge Impulse Inferencing Demo");

    if (!IMU.begin()) {
        ei_printf("Failed to initialize IMU!\r\n");
    }
    else {
        IMU.setContinuousMode();
        ei_printf("IMU initialized\r\n");
    }

    if (EI_CLASSIFIER_RAW_SAMPLES_PER_FRAME != 3) {
        ei_printf("ERR: EI_CLASSIFIER_RAW_SAMPLES_PER_FRAME should be equal to 3 (the 3 sensor axes)\n");
        return;
    }

    inference_thread.start(mbed::callback(&run_inference_background));

   
}

/**
 * @brief Return the sign of the number
 * 
 * @param number 
 * @return int 1 if positive (or 0) -1 if negative
 */
float ei_get_sign(float number) {
    return (number >= 0.0) ? 1.0 : -1.0;
}

/**
 * @brief      Run inferencing in the background.
 */
void run_inference_background()
{
    // wait until we have a full buffer
    delay((EI_CLASSIFIER_INTERVAL_MS * EI_CLASSIFIER_RAW_SAMPLE_COUNT) + 100);

    // This is a structure that smoothens the output result
    // With the default settings 70% of readings should be the same before classifying.
    ei_classifier_smooth_t smooth;
    ei_classifier_smooth_init(&smooth, 10 /* no. of readings */, 7 /* min. readings the same */, 0.8 /* min. confidence */, 0.3 /* max anomaly */);

    while (1) {
        // copy the buffer
        memcpy(inference_buffer, buffer, EI_CLASSIFIER_DSP_INPUT_FRAME_SIZE * sizeof(float));

        // Turn the raw buffer in a signal which we can the classify
        signal_t signal;
        int err = numpy::signal_from_buffer(inference_buffer, EI_CLASSIFIER_DSP_INPUT_FRAME_SIZE, &signal);
        if (err != 0) {
            ei_printf("Failed to create signal from buffer (%d)\n", err);
            return;
        }

        // Run the classifier
        ei_impulse_result_t result = { 0 };

        err = run_classifier(&signal, &result, debug_nn);
        if (err != EI_IMPULSE_OK) {
            ei_printf("ERR: Failed to run classifier (%d)\n", err);
            return;
        }

        // print the predictions
        ei_printf("Predictions ");
        ei_printf("(DSP: %d ms., Classification: %d ms., Anomaly: %d ms.)",
            result.timing.dsp, result.timing.classification, result.timing.anomaly);
        ei_printf(": ");

        // ei_classifier_smooth_update yields the predicted label
        const char *prediction = ei_classifier_smooth_update(&smooth, &result);
        ei_printf("%s ", prediction);
        // print the cumulative results
        ei_printf(" [ ");
        for (size_t ix = 0; ix < smooth.count_size; ix++) {
            ei_printf("%u", smooth.count[ix]);
            if (ix != smooth.count_size + 1) {
                ei_printf(", ");
            }
            else {
              ei_printf(" ");
            }
        }
        ei_printf("]\n");

        // Check if the predicted label is "fall"
        if (strcmp(prediction, "fall") == 0) {
            Serial.println("Fall detected!");
        } else {
            Serial.println("No fall detected.");
        }

        delay(run_inference_every_ms);
    }

    ei_classifier_smooth_free(&smooth);
}

/**
* @brief      Get data and run inferencing
*
* @param[in]  debug  Get debug info if true
*/
void loop()
{
  BLEDevice central = BLE.central();
    if (central) {
        Serial.println("Connected to central");
        while (central.connected()) {
            // Send notification or any minimal action
            fall.writeValue(1); // Just sending a small value
            delay(1000);
        }
        Serial.println("Disconnected from central");
        BLE.advertise();
    }

    while (1) {
        // Determine the next tick (and then sleep later)
        uint64_t next_tick = micros() + (EI_CLASSIFIER_INTERVAL_MS * 1000);

        // roll the buffer -3 points so we can overwrite the last one
        numpy::roll(buffer, EI_CLASSIFIER_DSP_INPUT_FRAME_SIZE, -3);

        // read to the end of the buffer
        IMU.readAcceleration(
            buffer[EI_CLASSIFIER_DSP_INPUT_FRAME_SIZE - 3],
            buffer[EI_CLASSIFIER_DSP_INPUT_FRAME_SIZE - 2],
            buffer[EI_CLASSIFIER_DSP_INPUT_FRAME_SIZE - 1]
        );

        for (int i = 0; i < 3; i++) {
            if (fabs(buffer[EI_CLASSIFIER_DSP_INPUT_FRAME_SIZE - 3 + i]) > MAX_ACCEPTED_RANGE) {
                buffer[EI_CLASSIFIER_DSP_INPUT_FRAME_SIZE - 3 + i] = ei_get_sign(buffer[EI_CLASSIFIER_DSP_INPUT_FRAME_SIZE - 3 + i]) * MAX_ACCEPTED_RANGE;
            }
        }

        buffer[EI_CLASSIFIER_DSP_INPUT_FRAME_SIZE - 3] *= CONVERT_G_TO_MS2;
        buffer[EI_CLASSIFIER_DSP_INPUT_FRAME_SIZE - 2] *= CONVERT_G_TO_MS2;
        buffer[EI_CLASSIFIER_DSP_INPUT_FRAME_SIZE - 1] *= CONVERT_G_TO_MS2;

        // and wait for next tick
        uint64_t time_to_wait = next_tick - micros();
        delay((int)floor((float)time_to_wait / 1000.0f));
        delayMicroseconds(time_to_wait % 1000);
    }

    
}

#if !defined(EI_CLASSIFIER_SENSOR) || EI_CLASSIFIER_SENSOR != EI_CLASSIFIER_SENSOR_ACCELEROMETER
#error "Invalid model for current sensor"
#endif

What am i doing wrong. Any help or suggestions would be much appreciated. Thanks in advance

Where is that?

Where is this?

Does your Nano33 BLE code work correctly with a standard central app like LightBlue or nrfConnect?

Once the BLE code is known to be solid, then it's time for App Inventor and any issues you may have on that side of things.

#include <ArduinoBLE.h>

BLEService fall_service("e267751a-ae76-11eb-8529-0242ac130003");
BLEIntCharacteristic fall("e267751b-ae76-11eb-8529-0242ac130003", BLERead | BLENotify);

void setup() {
    Serial.begin(9600);
    if (!BLE.begin()) {
        Serial.println("starting BLE failed!");
        while (1);
    }

    BLE.setLocalName("Fall_Detecter");
    BLE.setAdvertisedService(fall_service);
    fall_service.addCharacteristic(fall);
    BLE.addService(fall_service);
    BLE.advertise();
    Serial.println("Bluetooth device active, waiting for connections...");
}

void loop() {
    BLEDevice central = BLE.central();
    if (central) {
        Serial.println("Connected to central");
        while (central.connected()) {
            // Send notification or any minimal action
            fall.writeValue(1); // Just sending a small value
            delay(1000);
        }
        Serial.println("Disconnected from central");
        BLE.advertise();
    }
}


What is different between the connecting sketch and your sketch?

I uploaded this code then it connected to both app and nrfConnect. But with my code it is not connected in both

my sketch, i build a model using edge impulse and deployed it to the board. I added the ble connection part to the code but it is not connecting

Compare your sketch that does not connect to the sketch that connects.

Edge impulse and the inferencing is way out of my knowledge zone. I don't think I can be of much help and don't understand why it is interactive with the BLE and blocking connection.

Good luck with you project.