Connecting to WiFi

Exercise 1:

Verify the available access points before the activation of the ESP32 WiFi.
Study the MicroPython documentation on the WLAN class.

• Configure the WiFi interface as an access point.
• Check if the interface is already active and activate it, if not. Confirm that activation succeeded. If activation fails, emit an error message.

WiFi network before activation of the ESP32 access point	WiFi after activation

Exercise 2:

• Configure the ESP32 as "station interface"
• Verify if the interface is active, activate it if not.
• Scan the network and print all available information about the SSIDs found in a tabular format
• Connect the ESP32 with the router specifying the SSID and the password
• Verify that the connection was successful. (This may take a few seconds. Wait up to 10 s for the connection to be established)
• Print the IP address assigned to your ESP32
• Print the MAC address of the ESP32 WiFi interface
• Verify with ping that the ESP32 is accessible

This is what you will see if you try to ping the ESP32:

You can try ping also on the ESP32:

from uping import ping  
ping("the machine_to_be-checked")

Exercise 3:

Write a module: wifi.py which encapsulates the functionality of exercise 2. Upload the module to the /lib folder on the ESP32.

The code connecting to the ESP32 will then be as simple as this: from wifi import
connect()  

Exercise 4 :

Add a function returning the ESP32's IP address.

Read the current UTC time from the network using NTP. Set the real time clock on the ESP32. Provide a function that converts UTC into your local time.

Exercise 5 :

Write a TCP server and a client program running both on the PC. The server waits for a connection request from the client on port 5000, accepts it and sends a message to the client. After that, a prompt appears on the client and the user can type a message to be sent to the server. The server prints this message and creates a prompt on its side, where a message can be entered, to be sent to the client. A ping-pong communication is started. Typing the message "bye" on the client side terminates the connection.

Exercise 6 :

• Move the server to the ESP32. In this case, the WiFi initialization is needed before starting the server part. Test the communication as you did in exercise 5.
• Move the client to the ESP32 and run the server on the PC.

Exercise 7 :

Write a client on the ESP32 which reads the temperature and humidity from the DHT11 every 5s and packs the result into a message of the following form:
temperature [°C]: 25,humidity [%]: 56
Send this message to a server on the PC

The server parses the message and extracts the parameter names (temperature [°C] and humidity [%]) and the values and plots them in a dynamic plot created with matplotlib. The parameter names are used for the legend, the values are displayed graphically.

In the above plot, I put a finger on the DHT11, which quickly increases the measured humidity and more slowly increases the temperature.

-- Uli Raich - 2022-08-29

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