These services can have different streams of data. So to a ESP32 which has bluetooth included on the system more diectly. Users can use the Bluetooth HID Device APIs to make devices like keyboards, mice, joysticks and so on. The app will start scanning for BLE Devices and lists them out. Launch nRF Connect app and scan for devices. I am using the NimBLE library in the esp32. In this episode, we are having our ESP32 send/receive data to/from a Flutter app. On the other hand, when I use an Arduino Apr 4, 2023 · 19. you need to use written() instead of read() . 008 -> TFOCFG Out" line the ESP32 stops reading. It works with AT commands. Adafruit IO gives you the option to disconnect your microcontroller from your computer and run it off of USB power or a battery, and still be able to see the data. This is a very versatile communication protocol that can be used to send packets with up to 250 bytes. How BLE normally works is that a device advertises it's name like a beacon, this name can be seen by anyone and is used to identify the device. Envía un mensaje a LCD. [中文] ESP-IDF currently supports two host stacks. Esspecially an ESP32 is aware of having a bluetooth because it is a SystemOnChip ( in short SoC) My apologies for guessing too quick. Jul 14, 2020 · It sounds like you are want to receive messages from the phone to the bluetooth on the ESP32. Use small files to try. Processing takes this data, makes calculations, and sends it back to my ESP32. The program sets up an SPP server, which can receive and send data over a Bluetooth connection. Mar 13, 2018 · In this tutorial we will check how to receive data on a serial connection operating over Bluetooth classic. //Serial. Then the device can create various services that are seen by others when they connect to it. Jun 13, 2023 · RXD Pin → Data receive pin. The ESP32 (acting as the server) "notifies" the client via the TX characteristic UUID and data is sent to the ESP32 and received via the RX characteristic UUID. When notify on a characteristic is enabled and the sender writes to it, the new value is automatically sent to the receiver, without Jun 11, 2024 · Recommended reading: learn how to use ESP32 Bluetooth Classic with Arduino IDE to exchange data between an ESP32 and an Android smartphone. 6 KB) - This is a similar example to the previous one, but @Xolo has improved it with the help of ChatGPT. It will also send active location information to Android. Feb 5, 2015 · private static BluetoothClient BC = new BluetoothClient(EP); // The BT device that would connect. Jun 19, 2021 · ESP32 supports BLE and classic Bluetooth. Apr 1, 2024 · Click on the ‘scan’ icon on the top right corner. Notify. Go to Firebase and sign in using a Google Account. Sep 26, 2020 · I have some sensors sending their data using Bluetooth Low Energy about every 200 ms, but they are too far away to catch them all with just one receiver, and mesh has too high energy consumption. Step 3: After choosing your location and ticking the required boxes click ‘Create Project’. As you can see, it is very easy, and with this we can send and Apr 26, 2024 · Creating a Flutter App for ESP32: Makefile and Gateway for Bluetooth Data Transfer In this article, we will discuss how to create a Flutter app for ESP32 that allows for data transfer via Bluetooth. All my code will be available on my Patreon page:http Dec 27, 2023 · There are two main Bluetooth modes available on the ESP32: Bluetooth Classic – Used for traditional Bluetooth applications like streaming audio, file transfers, etc. It's all standard BLE stuff. May 9, 2019 · Clone the example “ BLE Alerts code “. recv_characteristic = aioble. You can load the previously saved value or do manually – select a speed of 115200, click the Terminal tab option on the left-hand side and select Force On both for Local echo and Local line editing options. Click ‘Continue’ to proceed further. Sep 21, 2020 · 2. Aug 24, 2020 · You can test if your ESP32 is correctly programmed using another terminal app (I use Serial Bluetooth Terminal for some tests, it works perfectly). The received data will be transmitted over Bluetooth wirelessly. This example shows how to both send data to and receive data from Adafruit IO. ESP32 Implementation. Click on ‘CONNECT’ and smart phone starts connection with ESP32 BLE Server. I want to shift the app to Bluetooth and did some research and found Bluetooth Serial for flutter. Now click ‘Continue’. The bluetooth-reading runs on a background thread. Receive. To use the Bluetooth functionality of the ESP32, you will need to include the appropriate libraries in your code and configure the ESP32 to act as a Bluetooth server or client. This tutorial is about send/receive image Android/Arduino by BT. You could change yours by editing the SerialBT. The documentation can be found here. Sending data is quite easy. My idea now is to use ESP32 modules as gateways/repeaters (their consumption doesn't matter. As you can see in the datasheet (below image) there are some lines also. Apr 2, 2022 · // similar thing with ESP-NOW: there is some kind of "letter-box" the received data will be stored into // the data-receiving into the "letter-box" runs in the backround similar to an interrupt // The received data will be catched up and must be copied into some kind of "letterbox" // any transporting service has some kind of procedure if you PowerManagement • Fine-resolutionpowercontrolthroughaselectionofclockfrequency,dutycycle,Wi-Fioperatingmodes, andindividualpowercontrolofinternalcomponents The communication between server and client will be through BLE where one ESP32 board acts as a BLE server and sends sensor readings to the ESP32 client that will receive them and display them in an OLED display. What is Bluetooth Low Energy? Bluetooth Low Energy, BLE for short, is a power-conserving variant of Bluetooth. The tests of this tutorial were performed using a DFRobot’s ESP32 module device integrated in a ESP32 development board. This project is divided into two parts: Part 1 – ESP32 BLE server. sleep_ms(1000) And here is the library I used : import struct. Search for the BLE scanner and download the app. [esp322pin_h] Search images: D1 R32 ESP32 This card has classic Bluetooth, BLE, WiFi, ADC, DAC, and more feature. I'll use the codes of Neil Kolban. I am plotting an ECG graph in the app and the delays are terrible( uploading values to firebase). Apr 1, 2024 · You learned some important basics of Bluetooth Communication in ESP32 SoC, how to setup Classic Bluetooth in ESP32, transfer data from a smart phone to ESP32 using Bluetooth and an extension project called Bluetooth Controlled LED using ESP32 (which can be easily modified to control a Relay). Enciende/apaga LED12/LED13. There are many applications where audio communication is required in digital devices such as adding a microphone or adding a speaker output to play some audio. #define USE_PIN // Uncomment this to use PIN during pairing. I made a program that I scaled down just to show the problem. It also allows you to send data to your microcontroller, such as NeoPixel colors. The atPlatf Apr 24, 2020 · This tutorial shows how to set up an ESP32 board to receive data from multiple ESP32 boards via ESP-NOW communication protocol (many-to-one configuration). h" String device_name = "ESP32-BT-Slave"; // Check if This enables data exchange over short distances, allowing the ESP32 to send and receive information like audio, files, and commands. Aug 7, 2021 · The write on the ESP32 side is a blank example code of the Arduino IDE, the read on the Android-side is made by the BLE-Library publisher. In this esp32 tutorial we will check how to receive data on a serial connection operating over Bluetooth classic. e. This will be an empty terminal where your typed message will arrive over Bluetooth. This is a cheap card ($ 5) with the d… Dec 24, 2023 · The app needs to receive and display data from an ESP32 via bluetooth serial. A Simple Arduino Bluetooth Music Receiver and Sender for the ESP32. the problem im facing with this whenever i run the program it shows address not found. Is there a neat way of receiving a message string with the esp32 BluetoothSerial library just like Serial. There are many models of the ESP32; most of them support Bluetooth, but a few do not. # Advertising payloads are repeated packets of the following form: # 1 byte data length (N + 1) # 1 byte type (see constants below) # N bytes type-specific data. When notify on a characteristic is enabled and the sender writes to it, the new value is automatically sent to the receiver, without I want to receive data packets from ESP32 and the ESP32 is working properly(I tested it using BLE scanner) but when I want to receive data on my own app, i receive the following data: I/flutter (23252): The received Value is ESP32 GET NOTI FROM DEVICE I/flutter (23252): The received Value is I/flutter (23252): The received Value is Jun 5, 2021 · I was assuming you are using some kind of bluetooth extra-module. May 2, 2021 · I am currently working on a project which is basically showing the Realtime readings from firebase database that are being uploaded by ESP32. After Jan 18, 2023 · 1. Apr 27, 2023 · Bluetooth LE Link Layer Controller. 22 to send data from ESP32 to Python via Bluetooth. MIT Companion and Installed. Part 2 – ESP32 BLE client. It supports both protocols, and Espressif provides libraries and code samples to get you up and working quickly. p110_esp32_ble_notifica_byte. ESP-WROOM-32, ESP32-WROOM-32 and ESP32-WROOM-32D BLE Mar 11, 2021 · 0. I am trying to change configration settings of E70 LoRa module. Verify and Uplink the script into the DOIT ESP32 Devkit V1. Discover the benefits of using Flutter and ESP32 for mobile app development and explore the step-by-step process of setting up your project and receiving data via Bluetooth. aia (220. With Atsign, all data between end points is end-to-end encrypted. private static BluetoothDeviceInfo BTDevice = new BluetoothDeviceInfo(BluetoothAddress. The variable "data" of the Android code is the received char-array. This ESP32 is connected to an OLED display and it prints the latest readings. VCC → Connect 5 V to this pin. One ESP32 will be the “sender” and the other ESP32 will be the “receiver”. Tested with Android 9 and Android 13. I've tried making adjustments and hacking together other examples but so far no luck. Step 1: Install ESP32 on the Arduino IDE. In that case you will use the recvWithStartEndMarkers() on the BluetoothSerial channel. The ESP32 is a microcontroller that provides an API for Bluetooth A2DP which can be used to receive sound data e. In the below lines of code it will check if any data is available on serial monitor if yes then it will send the data to BLUETOOTH device (for eg : our smartphone ) using esp32's Bluetooth. Sep 20, 2023 · DOWNLOAD FULL CODE. String device_name = "ESP32-ODS-BL"; Oct 31, 2023 · This code uses Bluetooth classic of ESP32 to establish a Serial Port Profile (SPP) server. You can now modify the previous sketch to make something useful now that you know how to exchange data using Bluetooth Serial. Jan 29, 2022 · Hi I appreciate help to use buttons on arduino or esp32 board and send data by bluetooth that I can use it in MIT app inventor. printf("Write binary file %s\r\n", path); File file = fs. h". Mar 24, 2021 · time. Send. Mar 17, 2021 · 16. The output is a PCM data stream, decoded from SBC format. The Bluetooth system can be divided into two different categories: Classic Bluetooth and Bluetooth Low Energy (BLE). For eg. This configuration is ideal if you want to collect data from several sensors nodes into one ESP32 board. For users to make a choice: For usecases involving classic Bluetooth as well as Bluetooth Sep 28, 2018 · ESP32 Bluetooth Low Energy - BLE tutorial with the sparkfun esp32 thing, receiving data from your phone. How to do with NimBLE. Once connected, simply sending 1 through the mobile to the ESP32 the led will turn on, and sending 0 it will turn off. Launch the terminal session. On the other hand, Apache NimBLE based stack is Bluetooth Low Energy only. Demonstration with BLE scanner app: Go to the play store. BLE’s primary application is short-distance transmission of small amounts of data (low bandwidth). I am using the BLE_client example but I cannot read the data properly. . Parse("94:21:97:60:07:C0")); private static NetworkStream stream = null; static void Main(string[] args) {. The boards will be programmed using Arduino IDE. Sep 16, 2021 · 1. Apr 19, 2024 · I made a plastic bot and I want to send the locations that I have created a listview from android to esp32. d effects the performance, but it does not drop it that much. _ADV_TYPE_FLAGS = const(0x01) Aug 21, 2023 · 19. - ESP32 sends automatically (Notify) a random number to App. Write the value 0x0001 to use the notify method, and 0x0002 to use the indicate method. If the incoming data is ‘1’ then we turn on the LED and if it is ‘0’ we should turn off the LED. 3 KB) To send information from ESP32 to the application I prefer to use Strings, but in this example I will use Bytes. Here ESP32 and classic Bluetooth: Wemos D1 R32 ESP32. - Board D1 R32 ESP32. A Bluetooth HID device is a device providing the service of human or other data input and output to and from a Bluetooth HID Host. To verify and uplink the script, press the “up arrow” icon found below: Once the code is uplinked, you will receive the message “ Uplink done ” in the terminal log of the Zerynth Studio. I manage to send a text from the smartphone to the esp32 with a classic bluetooth but not the other way around. And I don't say that whimsically because I know everything about BLE, I can say it because the library I recommended handles it fine, despite the fact that I know nothing about BLE. Step 4: Prepare the Mobile Application. The objective of this ESP32 Bluetooth Tutorial is to explain how to send data to the ESP32 using the Bluetooth RFCOMM protocol. Also for unique identification between sender and receiver (i. aia (197. May 16, 2020 · Hello friends, I'll write in this topic about BLE on ESP32, send and receive text, with clock and without clock. Control the ESP32 outputs when you receive a specific message, for example, or send data to your smartphone, such as sensor readings. Get your first ESP32 boar Jan 7, 2020 · 6. begin() procedure. Bluetooth is a wireless technology standard for exchanging data over short distances, with advantages including robustness, low power consumption, and low cost. Characteristic(device_service, _ENV_SENSE_RECV_UUID, write=True, read=True, notify=True, capture=True) and the receive it with. g. Jun 2, 2021 · I2S is an Inter-IC Sound protocol that is used mainly to transmit or receive the audio data in a synchronous serial port between two devices. Next we will need an object of class BluetoothSerial, which is the one we will use to initialize the Bluetooth stack on the ESP32 and to send the data. GND → Ground pin of the module. Mar 6, 2021 · Hello, I am trying to receive data through BLE on my M5Stack Core 2, which uses an ESP32. There are multiple Audio protocols available Apr 25, 2018 · ESP32 Bluetooth Tutorial: Receiving data through RFCOMM. in case you are actually interested in the data as well you need to enable capture when creating the characteristic. p110i_esp32_ble_notifica_Desliza. const char *pin = "1234"; // Change this to more secure PIN. You can see ‘ESP32-BLE-Server’ in the list. Nov 19, 2019 · Send and receive stuff from the device. Create a New Project. ESP32 supports dual-mode Bluetooth, meaning that both Classic Nov 18, 2021 · After creating a BLE server using ESP32, we can use a BLE application available on the Play store for testing purposes. aia (202. I've read about ESP32 now communication protocol (but don't know exactly if it's low power) Reason I want to use BLE is for low power usage. Arduino IDE. So, let's see how to use its built-in Bluetooth. Bluetooth® API. Applications Of Bluetooth Low Energy. - RegisterForBytes. Mar 1, 2020 · By the way, we named our Bluetooth device on ESP32 ‘JJS’ after our initials. import bluetooth. Feb 21, 2022 · I am using PyBluez 0. Runs the entire Bluetooth classic stack on ESP32. Alternatively, you can do communication between the Nano ESP32 board and the phone via the serial port. Now we are going to see several examples of classic Bluetooth, but using a Callback Dec 16, 2022 · im trying to print the values in bluetooth from esp32 and i want to receive the data in python by using bleak library. This is illustrated below with the communication protocols/speeds: Sending data from esp32 to pc works perfect. - Through a Slider the app sends data to ESP32. ESP32 device details: Address: 0C:B8:15:F6:78:4A Minor Type: PDA RSSI: -49 Services: 0x802000 < Braille ACL > char *devicename = "ESP32"; # Mar 13, 2018 · In this esp32 tutorial we will check how to receive data on a serial connection operating over Bluetooth classic. Click Get Started, and then Add project to create a new project. For users to make a choice: For usecases involving classic Bluetooth as well as Bluetooth May 2, 2023 · I wrote this code on my ESP32. This is a cheap card ($ 5) with the dimensions and shape of the Arduino UNO, but with the ESP32. Browse the GATT table and find the UUID and handle of the characteristic that controls the ESP32. Has faster data rates (2-3 Mbps) but higher power consumption. This document provides detailed command examples to illustrate how to utilize ESP32 Classic Bluetooth® AT Commands on ESP32. Bluetooth. This is a cheap card ($ 5) with the d… Overview. When you have received the complete message from the phone, you can echo it back out over Serial to the monitor like you do with showParsedData(). Once connected, it will display the list of services and its characteristics. Bluetooth Classic is well-suited for applications that require relatively higher data transfer rates, making it suitable for audio streaming or sending larger amounts of data quickly. import sys. There is a connection between them and I'm able to send data back and forth, but when trying to send messages very frequently, it's being delayed for almost 3 May 10, 2023 · Hi everyone! I am reading data from a sensor (MPU6050) with my ESP32 microprocessor and sending it to my pc via Bluetooth. I have an arduino that is sending a random integer between 1 and 100 and the ESP32 is reading it. BluetoothSerial SerialBT; void setup() {. It uses the ESP-IDF framework to configure and manage Bluetooth communication. In this topic we can find several examples of BLE: BLE ESP32. p110i_esp32_ble_notifica. The ESP32 is an excellent choice for working with both Bluetooth Classic and BLE. Here is my code. Conclusion. We’ll send a structure that contains a variable of type char, int, float, and boolean. . I found a few tutorials/examples related to this, but I haven't been able to get any of them to work. [comparativa] There is another smaller ESP32 mode… Jul 20, 2023 · 3. This card can be programmed with the Arduino IDE. Open the console to debug the status of the Step 2: The Explanation. The Bluedroid based stack (default) supports classic Bluetooth as well as Bluetooth Low Energy (Bluetooth LE). ESP32 works with Bluetooth classic and BLE, try with Bluetoot classic first. Obtiene el estado de los pulsadores. We begin our program by adding the header file BluetoothSerial which makes the ESP32 Bluetooth to work as Bluetoth SSP. Jun 11, 2020 · phone to sd card connected on esp32 board via its BT/BLE. The idea is to send a message from a smartphone, receive the message and update variables from that message which will affect what the Arduino does. Here is how the whole process looks like. When notify on a characteristic is enabled and the sender writes to it, the new value is automatically sent to the receiver, without Nov 16, 2023 · Web Bluetooth (also sometimes referred to as Web BLE) is a technology that allows you to connect and control BLE-enabled devices, like the ESP32, directly from your web browser using JavaScript. In our example, we use two different characteristics, TX and RX under the overarching "service" to send data to and receive data from a client (Android device) via these two channels. every few seconds and then receive it by bluetoothClient in MIT app, even in my case is possible to display values assinged to button press. from bluetooth import *. def input_and_send(): print("\nType something\n") while True: data = input() Remember to tick the Firebase term agreement. Jan 30, 2020 · In this tutorial we’ve shown you how to establish a two-way communication with two ESP32 boards using ESP-NOW. Data received on Bluetooth will be transmitted out on this pin. Basically you need to make ESP32 as a Web Server either using native WebServer library or ESPAsyncWebServer library. ) May 28, 2021 · Download and install nRF Connect app from the play store. Open the app and search for nearby devices. Feb 19, 2021 · 1. The goal is to send and reveive data from my phone (android with mitappinventor app) #include "BluetoothSerial. best regards Stefan Jan 31, 2022 · Hey I've got two devices that are connected via Bluetooth. Oct 26, 2023 · The ESP32 comes not only with Wi-Fi but also with Bluetooth and Bluetooth Low Energy (BLE). open(path, FILE_APPEND); To receive data from ESP32 Bluetooth LE server (through the notify or the indicate method), the ESP32 Bluetooth LE client needs to register with the server in advance. When notify on a characteristic is enabled and the sender writes to it, the new value is automatically sent to the receiver, without May 31, 2020 · phone to sd card connected on esp32 board via its BT/BLE. Step 2: Now enable ‘Google Analytics for this project’ by swiping the sliding button. In this second part of our ESP32 BLE Data Exchange Tutorial, we’ve explored crucial topics related to setting up data characteristics, maintaining persistent BLE connections, making your device discoverable or non-discoverable, and controlling LEDs with BLE commands. It is no issue to send data from esp32 by bluetooth periodically, eg. Establish SPP connection between phone (or PC) and ESP32 in Normal Transmission mode with IO capability set to NoInputNoOutput. Establish SPP connection between phone (or PC) and ESP32 in Passthrough mode with IO Nov 13, 2023 · 19. Jan 23, 2023 · The code is used to establish a Bluetooth connection between the ESP32 and an Android mobile application, and to send and receive data over this connection. May 26, 2024 · ESP32 with Bluetooth Classic & BLE. Nov 19, 2018 · Can two esp32 devices send and receive information from each other via bluetooth(ble)? I've been searching the internet but am not getting clear answers. BLE (Bluetooth Low Energy In the loop(), send and receive data via Bluetooth Serial. 6 KB) The Bluetooth LE specification includes a mechanism known as notify that lets you know when data’s changed. Jan 29, 2020 · To get you started with ESP-NOW wireless communication, we’ll build a simple project that shows how to send a message from one ESP32 to another. Notification. The tests of this ESP32 tutorial were performed using a DFRobot’s ESP-WROOM-32 device integrated in a ESP32 FireBeetle board. You would need to connect the board to the phone via a USB cable (using the phone's USB "On-The-Go" (OTG) capability). We will connect a DHT22 sensor with an ESP32 server that will transfer sensor data to the ESP32 client. ESP32 sends two random numbers from time to time to the app. The problem comes when sending data from pc to esp32, where I get data loss. Here is a quick example using native WebServer library: Apr 11, 2021 · We will connect to ESP32 by displaying the side menu and clicking on Devices, where we will select the device that is called as indicated above (ESP32_LED_Control). Bluetooth Low Energy, BLE for short, is a power-conserving variant of Bluetooth. Nov 18, 2022 · The ESP32 is a very powerful microcontroller with integrated WiFi and Bluetooth. We will cover the key concepts needed to build this app, including creating a Makefile, setting up the ESP32 as a gateway, and implementing Oct 16, 2018 · The idea of the program is to initialise a Serial Bluetooth connection using ESP32 and listen for data from paired devices. This is important as it will be used in Part B. You can create and write to a binary file using the function below (Arduino code) void writeBinary(fs::FS &fs, const char * path, uint8_t *dat, int len) {. the master is an ESP32 (which uses the BluetoothSerial library to connect and send data), and the slave is an Arduino Uno with a HC-05 module (connected with SoftwareSerial). readString (). 1. Step-By-Step Instructions To Connect The ESP32 To A Smartphone Over Bluetooth. Step 2: Program ESP32 with the code below. So far I have been receiving the data but it is not in the form it. Step 3: Understand the Code. h library, which will expose the functionalities needed to work with serial over Bluetooth. You connect the ESP32 transmit pin to the RXD pin. Everything is working normally, but I can't read all incoming data; after the "09:25:01. 0. Maximum range is around 10-100 meters. mac addresses, device names) I found Nov 25, 2021 · Subscribe. You have to send the file content as individual bytes and save it to SPIFFS. Mar 9, 2018 · The first thing we need to do is including the BluetoothSerial. With the esp32 gps module, it will go to the target coordinates in the list, respectively, with the case command. Yes the Log. But I don't know how to accept/receive data coming over Bluetooth serial using NimBLE. May 30, 2024 · If you want to send data via BLE, you will need to configure your sketch code to send that data via a BLE property. Connect to your ESP32 if it was found. App Inventor. ESP32 creates every 500 ms, random numbers from 1 to 99999 and notifies the number using 4 bytes: Dec 2, 2022 · Hello As I am a beginner on App Inventor and the Esp32, I have a problem that I cannot solve. #include "BluetoothSerial. ESP-NOW communication protocol can also be used with ESP8266 boards: Getting Started with ESP-NOW (ESP8266 NodeMCU with Arduino IDE). Dec 8, 2020 · arduino esp32 bluetooth recieve a whole string. With Web BLE, you can create web applications that interact with your ESP32 devices via Bluetooth, enabling you to control GPIO pins, exchange data Nov 11, 2021 · The ESP32 client connects to the BLE server and it is notified of its temperature and humidity characteristic values. May 14, 2024 · Exchange Data using Bluetooth Serial. May 12, 2020 · Hello friends, I'll write in this topic about BLE on ESP32, send and receive text, with clock and without clock. ill attach the code for the reference purpose. Jan 7, 2020 · 6. If not, use this code to check if your module is OK: #include "BluetoothSerial. The code starts by including several Jan 7, 2020 · 6. Give a name to your project, for example: ESP32 Firebase Demo. // By Evandro Copercini - 2018 // // This example creates a bridge between Serial and Classical Bluetooth (SPP) // and also demonstrate that SerialBT have the same functionalities of a normal Serial // Note: Pairing is authenticated automatically by this device #include "BluetoothSerial. Jun 18, 2023 · Abstract: Learn how to receive data with Bluetooth through a Flutter app in this comprehensive guide for ESP32 developers. After installing the app turn on the Bluetooth. 2023-06-18 by DevCodeF1 Editors. Follow the next instructions to create a new project on Firebase. It may not apply what I have written in post #7. The pin is specified on the line below. This tutorial will be very simple since we are going to use the BluetoothSerial library for the Arduino core, which exposes a very high level API much similar to the regular wired serial interface. Feb 23, 2023 · I want to show/print the string sent to esp32 over the Bluetooth serial. from your Mobile Phone and makes it available via a callback method. ESP32 sends random numbers. Most of the tutorials are from 2-3+ years ago and might be outdated. There are always dependency issues or other errors. TXD Pin → Data transmit pin. DFRobot Apr 25 2018 1535. You can then use functions provided by the library to send and receive data over Bluetooth . mc jj kh dv ed pz cb ul lx uw