ESP32 Wi-Fi

Introduction

Welcome to the Wokwi ESP32 MicroPython Wi-Fi Connection Guide!

Workwi Simulator Environment Setup

  • Navigate to Wokwi ESP32 MicroPython Project.
  • Start a new project and choose ESP32 as your microcontroller.
  • Wokwi simulates a Wi-Fi network that you can use to prototype IoT projects.

Understanding the Code

We'll write a simple MicroPython script to connect to a simulated Wi-Fi network named 'Wokwi-GUEST'.

Here's a breakdown of the code Connecting from MicroPython:

  1. Import libraries: network for networking functionality, and time for pausing the script.
  2. Print a message to the console to indicate the Wi-Fi connection process is starting.
  3. Create a WLAN (Wireless Local Area Network) object to interact with the Wi-Fi settings.
  4. Activate the WLAN interface.
  5. Attempt to connect to the 'Wokwi-GUEST' Wi-Fi network.
  6. Wait until the connection is established before proceeding.
  7. Print a message to the console to indicate the Wi-Fi connection is successful.

Writing MicroPython Code

Type the following MicroPython code directly into the Wokwi editor:

import network
import time

print("Connecting to WiFi", end="")
sta_if = network.WLAN(network.STA_IF)
sta_if.active(True)
sta_if.connect('Wokwi-GUEST', '')
while not sta_if.isconnected():
    print(".", end="")
    time.sleep(0.1)
print(" Connected!")

Workwi WiFi Connect

Accessing Web Page Data

Once connected to Wi-Fi, you can access web pages and retrieve data.

Here is a simple example using the `urequests` library to send an HTTP GET request to a webpage:

import requests

# URL of the CSV file
url = "https://data.moenv.gov.tw/api/v2/aqx_p_432?\
api_key=e8dd42e6-9b8b-43f8-991e-b3dee723a52d&format=CSV"

# Send an HTTP GET request to the URL
response = requests.get(url)

# Check if the request was successful (status code 200)
if response.status_code == 200:
    # Get the content of the response
    response_text = response.text
    
    # Print the content of the CSV data
    print(response_text)
    
else:
    print(f"Failed to download CSV data. Status code: {response.status_code}")

Accessing Web Page Data

Get AQI information

res = response_text.split("\n")

cols = res[2].split(',')
print(f"cols {cols}")
#print(cols.index('aqi'))
#get hualien data_type
for info in res:
    if '花蓮' in info:
        #print(info)
        print(info.split(',')[cols.index('aqi')])

https://colab.research.google.com/drive/1vplGqjSSyxE5yWMjj_MgCHJsCM7NcMHi?usp=sharing

WiFi AQI Information

Additional Resources

  • Explore Wokwi documentation for more details on ESP32 Wi-Fi networking and simulations: Wokwi ESP32 WiFi Networking Guide.
  • For advanced networking, like sending HTTP requests or establishing MQTT connections, learn about libraries like urequests and umqtt.

Conclusion

Now you've learned the basics of setting up a Wi-Fi connection on an ESP32 using MicroPython in Wokwi, and how to access web page data. Keep experimenting and happy coding!

RTC Module in MicroPython

  • The RTC module in MicroPython is used for real-time clock functionality.
     
  • It allows setting and retrieving the current date and time.
     
  • The datetime method can be used both to set and get the date and time.

RTC.datetime Method

  • The datetime method returns an 8-tuple when called without arguments.
     
  • The tuple format is:
    (year, month, day, weekday, hours, minutes, seconds, subseconds).
     
  • subseconds is hardware-dependent.
     
  • To set the date and time, pass an 8-tuple to datetime.

RTC Module Example code

from machine import RTC
# Create an RTC object
rtc = RTC()
# Set the date and time
rtc.datetime((2017, 8, 23, 1, 12, 48, 0, 0))
# Retrieve the current date and time
current_datetime = rtc.datetime()
print(f"current_datetime : {current_datetime}")

Time Module in MicroPython

  • The time module provides functions to work with time.
     
  • localtime([secs]) converts time in seconds since the Epoch to an 8-tuple.
     
  • If secs is not provided, the current time is used.
     
  • gmtime() returns UTC time, while localtime() returns local time.

Time.localtime and gmtime Functions

  • The format of the 8-tuple is:
    (year, month, mday, hour, minute, second, weekday, yearday).
  • year includes the century (e.g., 2014).
  • month is 1-12
  • mday is 1-31.
  • hour is 0-23; minute and second are 0-59.
  • weekday is 0-6 for Monday to Sunday
  • yearday is 1-366.

Time Example Code

import time

# Get the current time in seconds since the Epoch (Unix time)
current_time_seconds = time.time()

# Convert seconds since Epoch to a time tuple in local time
local_time_tuple = time.localtime(current_time_seconds)

# Format the time tuple into a human-readable date and time string
# The format is Year-Month-Day Hour:Minute:Second
formatted_time = "{:04d}-{:02d}-{:02d} {:02d}:{:02d}:{:02d}".format(
    local_time_tuple[0],  # Year
    local_time_tuple[1],  # Month
    local_time_tuple[2],  # Day
    local_time_tuple[3],  # Hour
    local_time_tuple[4],  # Minute
    local_time_tuple[5]   # Second
)

print("Current Local Time:", formatted_time)

ntptime Module in MicroPython

  • The ntptime module is used to synchronize the RTC with an NTP server.
     
  • This provides precise time, especially useful when the RTC is not accurate.
     
  • Use ntptime.settime() to update the RTC.

Download ntptime Module

Upload ntptime Module

import network, time, import ntptime

print("Connecting to WiFi", end="")
sta_if = network.WLAN(network.STA_IF)
sta_if.active(True)
sta_if.connect('Wokwi-GUEST', '')
while not sta_if.isconnected():
    print(".", end="")
    time.sleep(0.1)
print(" Connected!")

ntptime.host = 'tock.stdtime.gov.tw'
ntptime.timeout = 10
ntptime.settime()

# Convert seconds since Epoch to a time tuple in local time
local_time_tuple = time.localtime()
# Format the time tuple into a human-readable date and time string
# The format is Year-Month-Day Hour:Minute:Second
formatted_time = "{:04d}-{:02d}-{:02d} {:02d}:{:02d}:{:02d}".format(
    local_time_tuple[0],  # Year
    local_time_tuple[1],  # Month
    local_time_tuple[2],  # Day
    local_time_tuple[3],  # Hour
    local_time_tuple[4],  # Minute
    local_time_tuple[5]   # Second
)
print("Current Local Time:", formatted_time)

ntptime Example Code

ESP32 Networking Basics 🔗

ESP32 as an Access Point (AP)

  • Function:
    Creates a standalone Wi-Fi network that other devices can join.
  • Use Cases:
    Setting up a local network for IoT devices, workshops, or temporary setups.
  • Advantage:
    Useful where no existing Wi-Fi network is available, or for creating an isolated network.

Initialization

import network, time
ap = network.WLAN(network.AP_IF) # Initializes the access point interface
ap.active(False) # Deactivates the first AP interface
time.sleep(0.1) # Waits for 0.1 seconds to ensure the interface is properly deactivated
ap.active(True) # Reactivates the first AP interface

Configuring the Access Point

ap.config(ssid='MyESP32AP') # Sets the SSID and password of the AP
print('AP IP:', ap.ifconfig()[0]) # Displays the IP address of the ESP32 in AP mode

ESP32 as a Wi-Fi Station (STA)

  • Function:
    Connects ESP32 to an existing Wi-Fi network.
  • Use Cases:

      Access the internet

      interact with web services

      communicate with other network devices.

  • Advantage:

     Enables ESP32 to become part of a larger network, such as home automation.

Initialization

import network, time
wlan = network.WLAN(network.STA_IF) # Initializes the station interface
wlan.active(True) # Activates the WLAN interface
ssid = 'CSIE_C306'
passwd = '@ndhuc306'

Connecting to a Wi-Fi Network

connected = wlan.isconnected() # Check if the connection was successful
if not connected: # if it is not connected
    print(f'Trying to connect to {ssid}') # Display a message indicating an attempt to connect
    wlan.connect(ssid, passwd) # Attempt to connect to the Wi-Fi network again
    for _ in range(100): # Try to connect 100 times, waiting 0.1 seconds each time
        connected = wlan.isconnected() # Check if the connection was successful
        if connected:
           break # Break out of the loop if connected
        time.sleep(0.1) # Wait for 0.1 seconds before checking again
        print('.', end='') # Print progress dots to indicate ongoing connection attempts

if connected: # If connected successfully
    # Display successful connection and network configuration
    print(f'\nConnected to ssid {ssid}. Network config: {wlan.ifconfig()}') 
else: # If the connection failed
    print(f'\nFailed. Not Connected to: {ssid}') # Display a failure message

Access AQI Information

import urequests
# URL of the CSV file
url = "https://data.moenv.gov.tw/api/v2/aqx_p_432?\
api_key=e8dd42e6-9b8b-43f8-991e-b3dee723a52d&limit=1000&sort=ImportDate%20desc&format=CSV"

# Send an HTTP GET request to the URL
response = urequests.get(url)

# Check if the request was successful (status code 200)
if response.status_code == 200:
    # Get the content of the response
    response_text = response.text
    # Print the content of the CSV data
    print(response_text) 
else:
    print(f"Failed to download CSV data. Status code: {response.status_code}")

res = response_text.split("\n")
cols = res[2].split(',')
print(f"cols {cols}")
#print(cols.index('aqi'))
#get hualien data_type
for info in res:
    if '花蓮' in info:
        #print(info)
        aqi = info.split(',')[cols.index('aqi')]
        print(f"花蓮  AQI ： {aqi}")

Excercise

Show the AQI information to OLED

花蓮

 AQI ： 19

ESP32 Wi-Fi

By wschen

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ESP32 Wi-Fi

Discover the power of ESP32 Wi-Fi with this engaging presentation! Learn how to set up a simulator environment, write MicroPython code, connect to Wi-Fi, and access web page data. Plus, find additional resources to enhance your learning. Don't miss out!

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