前言

随着现在物联网设备的而越来越多，现在市场上出现越来越多的物联网设备，其中 ESP8266 是最受欢迎、价格便宜且易于使用的模块，它可以将您的硬件连接到互联网。

今天我们就以ESP8266和STM32来实现一台网络服务器，我们使用 ESP8266 将 STM32F103C8 连接到互联网。 ESP8266 Wi-Fi 模块与 STM32F103C8 板接口，并将数据发送到 ESP8266 网络服务器上托管的网页。

所需硬件

STM32F103C8板ESP8266 无线无线模块笔记本电脑和无线网络热点

ESP8266 模块

大多数人将 ESP8266 称为 WIFI 模块，但它实际上是一个微控制器。ESP8266 是乐鑫公司（一家总部位于上海的公司）开发的微控制器的名称。该微控制器具有执行WIFI相关活动的能力，因此被广泛用作WIFI模块。

引脚说明

GND：接地TX：发射传输数据位GPIO2：通用输入/输出 2CH_PD：使能GPIO0：通用输入/输出0RST：复位RX：接收数据位VCC：+3.3 V

常用AT指令

AT 命令用于与 ESP8266 通信。下表显示了一些常用的 AT 命令

电路图和连接

下图显示了STM32和ESP8266无线模块之间的连接。

SMT32F103C8具有三套UART串行通信。在下图中，您可以看到相同的以下引脚： ESP8266 使用串行通信与STM32进行通讯。所以这里 ESP8266 的 TX 和 RX 都与 STM32 板的串行 2 端口 （PA2 和 PA3） 连接。

代码解释

ESP8266 与 STM32 的接口工作非常简单。您可以在本教程末尾的代码中找到完整的工作。

首先，我们需要按照电路图中所示进行电路连接。上传代码后，打开串行监视器（工具>>串行监视器）以查看发生的情况。您将在串行监视器上看到IP地址，从串行监视器复制IP地址并将其粘贴到浏览器中，然后单击Enter以查看我们的网页。请记住将计算机和 ESP8266 模块连接到同一 Wi-Fi 网络上。

完整的代码在最后给出，并通过注释很好地解释了，在这里我们解释了其中的几个重要部分。

首先，我们使用以下两个语句开始串行监视器和 ESP8266 的串行通信：

Serial.println(cmd);

Serial2.println(cmd);

注意： 我使用过STM32串行2端口的引脚（PA2，PA3），因为它可以承受3.3V。

然后，我们需要让 ESP8266 准备就绪，方法是通过重置任何旧的已连接的 AP 并将其设置为 AP 和 STA 来退出任何旧的 AP

connect_wifi("AT",100); //Sends AT command with time(Command for Acknowledgement)

connect_wifi("AT+CWMODE=3",100); //Sends AT command with time (For setting mode of Wi-Fi)

connect_wifi("AT+CWQAP",100); //Sends AT command with time (for Quit AP)

connect_wifi("AT+RST",5000); //Sends AT command with time (For RESETTING WIFI)

然后将 ESP8266 与无线网络连接。您必须填写您的Wi-Fi详细信息，如下面的代码所示：

connect_wifi("AT+CWJAP=\"Pramo\",\"pokemon08\"",7000); //provide your WiFi username and password here

然后我们获取 ESP8266 模块的 IP 地址，并使用下面的代码将其显示在串行监视器上

Serial2.println("AT+CIFSR"); //GET IP AT COMMAND

if(Serial2.find("STAIP,")) //This finds the STAIP that is the STATIC IP ADDRESS of ESP8266

Serial.print(IP); //prints IP address in Serial monitor

接下来，我们将为网页编写 HTML 代码。要将HTML代码转换为Arduino代码，您可以使用此链接。

HTML在线转Arduino代码

webpage = "

Welcome to Circuit Digest

"; //This is the heading line with black font colour

String name="

Circuit Digest

A community of electrical and electronics students, engineers and makers

";

String data="

Data Received Successfully.....

"; //These two lines are of two paragraph

webpage = "

webpage+="\">Click Here to get into circuitdigest.com"; //At last we insert the hyperlink to link the website address

接下来在void send() 函数中，我们使用发送网络数据函数打印了HTML，并使用AT + CIPCLOSE = 0关闭了服务器连接

完成所有工作后，您可以通过在任何 Web 浏览器中打开 ESP8266 的 IP 并单击网页上显示的链接来测试工作，单击此处进入 circuitdigest.com，如下所示 单击链接后，您会在网页上看到一条文本，上面写着Data Received Successfully.....

完整代码

//Interfacing ESP8266 Wi-Fi with STM32F103C8

//CIRCUIT DIGEST

//NOTE: Serial is serial monitor with baud rate(9600)

//NOTE: Serial2 (TX2, RX2)is connected with ESP8266(RX,TX)respectively with baud rate (9600)

String webpage = ""; //String variable to store characters

int i = 0, k = 0, x = 0; //integer variables

String readString; //using readString feature to read characters

boolean No_IP = false; //boolean variables

String IP = ""; //String variable to store data

char temp1 = '0'; //character variable

String name = "

Circuit Digest

A community of electrical and electronics students, engineers and makers

"; //String with html notations

String data = "

Data Received Successfully.....

"; //String with html

void check4IP(int t1) //A function to check ip of ESP8266

{

int t2 = millis();

while (t2 + t1 > millis())

{

while (Serial2.available() > 0)

{

if (Serial2.find("WIFI GOT IP"))

{

No_IP = true;

}

}

}

}

void get_ip() //After cheacking ip ,this is a function to get IP address

{

IP = "";

char ch = 0;

while (1)

{

Serial2.println("AT+CIFSR"); //GET IP AT COMMAND

while (Serial2.available() > 0)

{

if (Serial2.find("STAIP,")) //This finds the STAIP that is the STATIC IP ADDRESS of ESP8266

{

delay(1000);

Serial.print("IP Address:");

while (Serial2.available() > 0)

{

ch = Serial2.read(); //Serial2 reads from ESP8266

if (ch == '+')

break;

IP += ch;

}

}

if (ch == '+')

break;

}

if (ch == '+')

break;

delay(1000);

}

Serial.print(IP); //prints IP address in Serial monitor

Serial.print("Port:");

Serial.println(80);

}

void connect_wifi(String cmd, int t) //This function is for connecting ESP8266 with wifi network by using AT commands

{

int temp = 0, i = 0;

while (1)

{

Serial.println(cmd); //Sends to serial monitor

Serial2.println(cmd); //sends to ESP8266 via serial communication

while (Serial2.available())

{

if (Serial2.find("OK"))

i = 8;

}

delay(t);

if (i > 5)

break;

i++;

}

if (i == 8)

Serial.println("OK");

else

Serial.println("Error");

}

void wifi_init() //This function contains AT commands that passes to connect_wifi()

{

connect_wifi("AT", 100); //Sends AT command with time(Command for Achknowledgement)

connect_wifi("AT+CWMODE=3", 100); //Sends AT command with time (For setting mode of Wifi)

connect_wifi("AT+CWQAP", 100); //Sends AT command with time (for Quit AP)

connect_wifi("AT+RST", 5000); //Sends AT command with time (For RESETTING WIFI)

check4IP(5000);

if (!No_IP)

{

Serial.println("Connecting Wifi....");

connect_wifi("AT+CWJAP=\"Pramo\",\"pokemon08\"", 7000); //provide your WiFi username and password here

} else

{

}

Serial.println("Wifi Connected");

get_ip();

connect_wifi("AT+CIPMUX=1", 100); //Sends AT command with time (For creating multiple connections)

connect_wifi("AT+CIPSERVER=1,80", 100); //Sends AT command with time (For setting up server with port 80)

}

void sendwebdata(String webPage) //This function is used to send webpage datas to the localserver

{

int ii = 0;

while (1)

{

unsigned int l = webPage.length();

Serial.print("AT+CIPSEND=0,");

Serial2.print("AT+CIPSEND=0,");

Serial.println(l + 2);

Serial2.println(l + 2);

delay(100);

Serial.println(webPage); //sends webpage data to serial monitor

Serial2.println(webPage); //sends webpage data to serial2 ESP8266

while (Serial2.available())

{

if (Serial2.find("OK"))

{

ii = 11;

break;

}

}

if (ii == 11)

break;

delay(100);

}

}

void setup()

{

Serial.begin(9600); //begins serial monitor with baud rate 9600

Serial2.begin(9600); //begins serial communication with esp8266 with baud rate 9600 (Change according to your esp8266 module)

wifi_init();

Serial.println("System Ready..");

}

void loop()

{

k = 0;

Serial.println("Please Refresh your Page");

while (k < 1000)

{

k++;

while (Serial2.available())

{

if (Serial2.find("0,CONNECT"))

{

Serial.println("Start Printing");

Send();

Serial.println("Done Printing");

delay(1000);

}

}

delay(1);

}

}

void Send() //This function contains data to be sent to local server

{

webpage = "

Welcome to Circuit Digest

";

sendwebdata(webpage);

webpage = name;

sendwebdata(webpage);

delay(1000);

webpage = "

webpage += "\">Click Here to get into circuitdigest.com";

webpage += data;

sendwebdata(webpage);

Serial2.println("AT+CIPCLOSE=0"); //Closes the server connection

}

结语

看到这里相信你已经知道了使用共ESP266与STM32通讯的整个思路和流程了，快拿你的设备来试一下吧，相信你也可以成功的！

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