Espressif ESP32 Manuel utilisateur

ESP32 Bluetooth Networking

User Guide

Version 1.1

Espressif Systems

About This Guide

This document provides a guide to using ESP32 in Bluetooth networking for IoT devices

with examples.

Release Note

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Certiﬁcation

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Date

Version

Release notes

2017.03

V1.0

First release.

2019.05

V1.1

Update ﬁgures.

Content

1. Introduction!1".............................................................................................................................

1.1. Overview!1"....................................................................................................................................

1.2. EspBluﬁ!1"......................................................................................................................................

2. APIs for Networking Development!3".........................................................................................

2.1. BluFi Protocol!3".............................................................................................................................

2.2. APIs on ESP32 End!3"....................................................................................................................

2.3. APIs on the EspBluﬁ APK End!4"...................................................................................................

3. ESP32 Bluetooth Networking Examples!5"................................................................................

3.1. Hardware and Software Preparation!5"..........................................................................................

3.2. Setting ESP32 to Station Mode!5".................................................................................................

3.3. Setting ESP32 as a SoftAP!9........................................................................................................

1. Introduction

1.1. Overview

The ESP32, as a single 2.4 GHz Wi-Fi and Bluetooth combo chip, supports Wi-Fi setups

via both SmartConﬁg and Bluetooth. Users can use ESP32 for secure conﬁguration of Wi-

Fi networking for IoT devices.

Using Bluetooth for conﬁguring Wi-Fi network presents the following advantages:

•The Bluetooth protocol is open and scalable.

•By using Bluetooth protocol, users can easily discover nearby devices via Bluetooth

beacons.

•The Bluetooth protocol is secure, because the authentication of the device is done

over a secure Bluetooth connection before the password is sent to the device.

•Users can also transmit data over Bluetooth to a smartphone, even when the router

is not working. The phone can then uploads the data to the Internet.

•The phone can now also connect to the Bluetooth device and send commands

directly to control the device if the Wi-Fi network is down.

1.2. EspBluﬁ

ESP32 is compliant with Bluetooth v4.2 BR/EDR and BLE speciﬁcations. Espressif has

developed the app EspBluﬁ speciﬁcally for Bluetooth networking of IoT devices. The app is

supported on Android 4.3 and above. For smartphones of Android 6.0 or above, because

of Google’s modiﬁcation to the Android API, users must give their permission for access to

their current location and enable the location information module to start the Bluetooth

scanning.

•EspBluﬁ can be downloaded via: https://github.com/EspressifApp/EspRelease/tree/

master/EspBluﬁ

•Open EspBluﬁ after downloading it. In the user interface as shown in Figure 1-1, click on

the !icon in the upper right corner.

Figure 1-1. EspBluﬁ User Interface

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1. Introduction

•The Conﬁgure button will be shown in the interface and click this button.

Figure 1-2. CONFIGURE Button

•Conﬁgure the length of BLE mtu, BLE device ﬁltering, and check the version of the app

and Bluﬁ repository.

Figure 1-3. CONFIGURE Interface!

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2. APIs for Networking Development

2. APIs for Networking

Development

2.1. BluFi Protocol

Protocol documentation: https://docs.espressif.com/projects/esp-idf/en/latest/api-guides/

bluﬁ.html

2.2. APIs on ESP32 End

In the program of ESP32, security-related processes such as key establishment are

determined and developed by the users. The app sends the “negotiate data” to ESP32 and

the data packets will be sent to the application layer. If the data is not handled by the

application layer, DH algorithm provided by BluFi can be used to exchange the key. The

application layer needs to register relevant callback functions to BluFi. Table 2-1 provides

description of those functions.

Table 2-1. Security-Related Functions

Function

Description

typedef void

(*esp_blufi_negotiate_data_handler_t)

(uint8_t *data, int len, uint8_t

**output_data, int *output_len, bool

*need_free);

•This function is used to receive the “negotiate

data” during key exchange. The data to be sent

should be output by passing the parameters

output_data and output_len to BluFi.

•After BluFi calls negotiate_data_handler,

output_data output by

negotiate_data_handler is sent.

•Since the length of data to be sent is not deﬁnite,

**output_data has to malloc a part of

memory or use global variables to release memory

via need_free.

typedef int (*

esp_blufi_encrypt_func_t)(uint8_t iv8,

uint8_t *crypt_data, int cyprt_len);

The length of the encoded and decoded data must

be the same. iv8 in this function means the 8-bit

sequence of the packets. It can be used for eight bits

of the initialization vector.

typedef int (*

esp_blufi_decrypt_func_t)(uint8_t iv8,

uint8_t *crypt_data, int crypt_len);

The length of the encoded and decoded data must

be the same. iv8 in this function means the 8-bit

sequence of the packets. It can be used for eight bits

of the initialization vector.

typedef uint16_t

(*esp_blufi_checksum_func_t)(uint8_t

iv8, uint8_t *data, int len);

The function is used to calculate the checksum.

Calling this function returns the value of checksum.

The returned value will be compared with the

checksum at the end of the packet by BluFi.

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2. APIs for Networking Development

2.3. APIs on the EspBluﬁ APK End

• Source code of EspBluﬁ for Android: https://github.com/EspressifApp/

EspBluﬁForAndroid

• Documentation of EspBluﬁ for Android: https://github.com/EspressifApp/

EspBluﬁForAndroid/blob/master/doc/

Introduction_to_the_EspBluﬁ_API_Interface_for_Android__cn.md

• Source code of EspBluﬁ for iOS: https://github.com/EspressifApp/EspBluﬁForiOS

• Documentation of EspBluﬁ for iOS: https://github.com/EspressifApp/EspBluﬁForiOS/

blob/master/doc/Bluﬁ_APP_API_for_iOS_CN.md

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3. ESP32 Bluetooth Networking Examples

3. ESP32 Bluetooth Networking

Examples

3.1. Hardware and Software Preparation

•1 ×ESP32 module

•1 ×PC, connected to the module to supply power and print log for ESP32.

•1 ×smartphone (Android 4.3 or above)

•Download and install EspBluﬁ on the smartphone. Turn on the Wi-Fi and Bluetooth

capabilities on the phone. The link for downloading EspBluﬁ is!

https://github.com/EspressifApp/EspRelease/tree/master/EspBluﬁ

3.2. Setting ESP32 to Station Mode

1. Power on the module. The following log will be output to the serial port tool:

2. Open the EspBluﬁ app, and refresh the interface by swiping down from the top of the

screen. The nearby Bluetooth-enabled devices will be shown on the screen.

Figure 3-1. EspBluﬁ Interface

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3. ESP32 Bluetooth Networking Examples

3. Click on the ESP32 device in the interface as Figure 3-1 shows, and click Connect

button !to establish Bluetooth connection to it. Successful connection will yield the

interface shown in Figure 3-2.

Figure 3-2. Interface Showing Successful Connection

Meanwhile, the following log will be output to the serial port tool:

4. Click on the Networking button !to conﬁgure the network, get the dropdown menu

for network conﬁguration, as Figure 3-3 shows:

📖Note:

If the Networking button is not shown or can not be clicked in the interface of Figure 3-2, it means that

Bluetooth connection has failed.

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3. ESP32 Bluetooth Networking Examples

Figure 3-3. Network Conﬁguration Interface

5. Select the device mode from the dropdown menu, as Figure 3-4 shows. (BluFi

networking supports the following three modes: Station, SoftAP, and Station+SoftAP.)

Figure 3-4. Selecting Device Mode

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