Arduino BLE Periodic Advertising

Hardware Nano Family Nano 33 BLE
1

I want to broadcast data using periodic advertising by using the NONCONN_NONSCANNABLE advertising mode to conserve power but I cannot be able to send DHT11 sensor data with the advertising packets as it displays the adv_parameters only on the nrf connect app. I have attached my code, Can anyone please help me with this issue to sort this problem.

#include <BLEDevice.h>
#include <BLEAdvertising.h>
#include <DHT.h>

#define DHTPIN 19       // Pin connected to the DHT sensor
#define DHTTYPE DHT11   // DHT 11

DHT dht(DHTPIN, DHTTYPE);

// BLE advertising parameters
esp_ble_gap_ext_adv_params_t ext_adv_params = {
    .type = ESP_BLE_GAP_SET_EXT_ADV_PROP_NONCONN_NONSCANNABLE_UNDIRECTED,
    .interval_min = 0x40,  // 64 * 0.625 ms = 40 ms
    .interval_max = 0x40,  // 64 * 0.625 ms = 40 ms
    .channel_map = ADV_CHNL_ALL,
    .own_addr_type = BLE_ADDR_TYPE_RANDOM,
    .peer_addr_type = BLE_ADDR_TYPE_RANDOM,
    .peer_addr = {0, 0, 0, 0, 0, 0},
    .filter_policy = ADV_FILTER_ALLOW_SCAN_ANY_CON_ANY,
    .tx_power = EXT_ADV_TX_PWR_NO_PREFERENCE,
    .primary_phy = ESP_BLE_GAP_PHY_1M,
    .max_skip = 0,
    .secondary_phy = ESP_BLE_GAP_PHY_2M,
    .sid = 1,
    .scan_req_notif = false,
};

// BLE periodic advertising parameters
esp_ble_gap_periodic_adv_params_t periodic_adv_params = {
    .interval_min = 0x320,  // 1000 ms interval
    .interval_max = 0x640,  // 2000 ms interval
    .properties = 0,  // No additional properties
};

uint8_t addr_2m[6] = {0xc0, 0xde, 0x52, 0x00, 0x00, 0x02};

// BLE Multi-advertising instance
BLEMultiAdvertising advert(1);  // max number of advertisement data

void setup() {
    Serial.begin(115200);
    Serial.println("Multi-Advertising with Sensor Data...");

    // Initialize DHT sensor
    dht.begin();

    // Initialize BLE
    BLEDevice::init("");

    // Set up the advertising parameters
    advert.setAdvertisingParams(0, &ext_adv_params);

    // Start the advertising
    advert.start();

    // Set up periodic advertising parameters
    advert.setPeriodicAdvertisingParams(0, &periodic_adv_params);
    advert.startPeriodicAdvertising(0);

    // Wait for BLE stack to settle
    delay(1000);
}

void loop() {
    // Read data from DHT11 sensor
    float temperature = dht.readTemperature();
    float humidity = dht.readHumidity();

    // Check if any reads failed
    if (isnan(temperature) || isnan(humidity)) {
        Serial.println("Failed to read from DHT sensor!");
        delay(5000);  // Retry after 5 seconds
        return;
    }

    // Create advertisement data payload with sensor values
    char advData[30];
    snprintf(advData, sizeof(advData), "T:%.1fC H:%.1f%%", temperature, humidity);

    // Create raw advertisement data
    uint8_t periodic_adv_raw_data[30];
    size_t data_len = strlen(advData);
    periodic_adv_raw_data[0] = data_len + 1;  // Length of the payload
    periodic_adv_raw_data[1] = 0x09;  // Type: Complete Local Name
    memcpy(&periodic_adv_raw_data[2], advData, data_len);

    // Update the advertising data
    advert.setPeriodicAdvertisingData(0, sizeof(periodic_adv_raw_data), periodic_adv_raw_data);

    // Log the advertised data
    Serial.print("Advertising data: ");
    Serial.println(advData);

    // Sleep for a while to optimize power consumption
    delay(10000);  // Adjust delay as needed
}
2

have you looked at the library's example

may be updating the completeRawAdvertisingData array from time to time would do.

remember the library has limits

Advertising and GAP

BLE devices let other devices know that they exist by advertising using the General Advertising Profile (GAP). Advertising packets can contain a device name, some other information, and also a list of the services it provides.

Advertising packets have a limited size. You will only be able to fit a single 128-bit service UUID in the packet. Make sure the device name is not too long, or you won’t even be able to fit that.

3

I have tried this thing I periodically update my sensor value in the loop and convert them in the MSB AND LSB and update it in the manufacture data but the thing is the advertisement get disapprar no ble dvice is shown in the scanner app

4

Try making this global scope so that it does not disappear when the loop is done

5

ok thankyou it works

6

Great - have fun!

(the reason was that the library likely keep only a pointer to the data and if you have just a scope limited to the function, by the time it's getting used the function call is done and memory on the stack is freed and being used by something else - thus the pointer is just pointing at garbage).