Connecting ESP8266 with STM32F103C8: Creating a Webserver (2025)

If you think about future technologies then the two names, which immediately comes in your mind, are Artificial Intelligence (AI) and Internet of Things (IoT). AI is still in its initial stage and there is lot more to be developed. But IoT is in Growth stage and lot of IoTbased products are already there in the market. Also there are many tools and hardwareavailable in the market to make your product talking with ‘things’ in the internet. Among them ESP8266 is the most popular, cheap and easy-to-use module, which can connect your hardware to the Internet.

We have developed lot of IoT Projects using ESP8266, which not only includes basic interfacing with other microcontrollers like Arduino, PIC, AVR but also includes many intelligent projects like IOT based Air Pollution Monitoring,Vehicle Tracking on Google Maps, IOT based Voice Controlled Home Automation etc. Today in this tutorial, we use ESP8266 to connect STM32F103C8 to the internet. Here we will interface ESP8266 Wi-Fi module with our Blue Pill STM32F103C8 board and send the data to a webpage hosted on ESP8266 webserver.

Components Required

• Blue Pill STM32F103C8 board
• ESP8266 Wi-Fi module
• Laptop & Wi-Fi hotspot

ESP8266 Wi-Fi Module

Most people call ESP8266 as a WIFI module, but it is actually a microcontroller. ESP8266 is the name of the microcontroller developed by Espressif Systems which is a company based out of shanghai. This microcontroller has the ability to perform WIFI related activities henceit is widely used as a WIFI module.

1. GND, Ground (0 V)
2. TX, Transmit data bit X
3. GPIO 2, General-purpose input/output No. 2
4. CH_PD, Chip power-down
5. GPIO 0, General-purpose input/output No. 0
6. RST, Reset
7. RX, Receive data bit X
8. VCC, Voltage (+3.3 V)

AT command is used for communicating with ESP8266. The table below shows some of useful AT commands

We have created a series of tutorials to understand the ESP8266, starting from beginner to advance level:

• Getting Started with ESP8266 WiFi Transceiver (Part 1)
• Getting Started with ESP8266 (Part 2): Using AT Commands
• Getting Started with ESP8266 (Part 3): Programming ESP8266 with Arduino IDE and Flashing its Memory

Circuit Diagram and connections

Below schematic shows the connection between STM32 & ESP8266 Wi-Fi module.

Refer below table to connect ESP8266 pins with STM32 pins:

SMT32F103C8 has three sets of UART serial communication. In the below image you can see the following pins for the same:

ESP8266 uses serial communication for interacting with microcontroller. So here TX & RX of ESP8266 are connected with serial2 port (PA2 & PA3) of STM32 board.

Working & Code Explanation

The working of interfacing ESP8266 with STM32 is very simple. You can find the complete working in the video given at the end of this tutorial along with the code.

We use arduino IDE to write and upload the code to STM32. Learn more about using Arduino IDE to program STM32 board.

First we need to do the circuit connections as shown above in the circuit diagram. After uploading the code, open Serial Monitor (Tools>>Serial Monitor) to view what’s happening. You will see IP address on serial monitor, copy the IP address from serial monitor and paste it in browser and click enter to see our webpage. Remember to connect your computer and ESP8266 module on the same Wi-Fi network.

Complete code is given at the end and well explained by the comments, here we are explaining few important part of it.

First we begin serial communication for serial monitor and for ESP8266, by using following two statements:

Serial.println(cmd);Serial2.println(cmd);

NOTE: I have used pins (PA2, PA3) of Serial2 port of STM32 because it is 3.3V tolerant.

Then we need to get the ESP8266 ready by quitting any old connected AP by resetting it and setting Wi-Fi mode as both AP & STA

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)

Then connect the ESP8266 with Wi-Fi network. You have to fill in your Wi-Fi details as shown in below code:

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

Then we get the IP address of the ESP8266 module and show it on serial monitor by using below code

Serial2.println("AT+CIFSR"); //GET IP AT COMMANDif(Serial2.find("STAIP,")) //This finds the STAIP that is the STATIC IP ADDRESS of ESP8266Serial.print(IP); //prints IP address in Serial monitor

Next we will write HTML code for the webpage. To convert HTML code into Arduino code, you can use this link.

webpage = "<h1>Welcome to Circuit Digest</h1><body bgcolor=f0f0f0>"; //This is the heading line with black font colourString name="<p>Circuit Digest</p><p>A community of electrical and electronics students, engineers and makers</p>";String data="<p>Data Received Successfully.....</p>"; //These two lines are of two paragraphwebpage = "<a href=\"http://circuitdigest.com/\"";webpage+="\">Click Here to get into circuitdigest.com</a>"; //At last we insert the hyperlink to link the website address

Next in void send() function, we have printed HTML using sendwebdata functionand closed the server connection using AT+CIPCLOSE=0

void Send() //This function contains data to be sent to local server{ webpage = "<h1>Welcome to Circuit Digest</h1><body bgcolor=f0f0f0>"; sendwebdata(webpage); webpage=name; sendwebdata(webpage); delay(1000); webpage = "<a href=\"http://circuitdigest.com/\""; webpage+="\">Click Here to get into circuitdigest.com</a>"; webpage+=data; sendwebdata(webpage); Serial2.println("AT+CIPCLOSE=0"); //Closes the server connection}

After all of the work, you can test the working by opening the ESP8266’s IP in any web browser and click on the link shown on the webpage, Click Here to get into circuitdigest.com, like below

After clicking the link, you see a text on the webpage saying “Data Received Successfully.....”

Complete code with Demonstration Video is given below.