How to Build a ESP32 Weather Monitor Module
Here I will show my attempt to build a wireless weather monitor module, using ESP32 microcontroller, that connects to the internet via WiFi and pulling some useful weather status information from OpenWeatherMap.org let’s say every 5 minutes.
Main features
- Pulling data through wireless connection
- Various weather info are available including
- temperature, feels-like temperature, etc
- pressure,
- humidity
- wind speed
- visibility
- Temperature status indicator LEDs:
- Red (too hot)
- green (normal)
- blue (too cold)
- Weather indicator in case of extreme weather
(e.g. rain or snow)- Yellow LED
- Buzzer (single or double beep)
- Change texts color when the weather status is not normal
(e.g. high wind speed, low visibility, rain) - Report date and time of the latest update using NTP client
How does it work?
The brain of the module is ESP32 microcontroller, a low-powered with built-in WiFi and Bluetooth functionality, which submits an HTTP request to OpenWeatherMap as the weather data server. The server returns a response to the ESP32 which contains all the required information. Finally, it reads the data into JSON format, represents them in a TFT display, and reacting to them using, changing the text color, different LED indicators, or generating a gentle beep sound.
Prerequisites
- Access:
- Connection to a WiFi network
- OpenWeatherMap enabled API to request weather data (account creation is required, see here)
- Hardware:
- EPS32 microcontroller
- 1.8 SPI TFT 128x160 display
- Four LEDs (red, green, blue, and yellow)
- A Piezo buzzer
- Few 100 Ohm resistors for LEDs
- A breadboard and some wires (or soldering prototype board)
- Software
- Arduino IDE with ESP32 Add-on
- Arduino json library
- Adafruit TFT display driver library
Wiring
The wiring is pretty straightforward as follows (see ESP32 Pinout Reference):
- TFT display pins:
- CS ➡ 12
- RST ➡ 14
- DC ➡ 13
- SCLK ➡ 22
- MOSI ➡ 21
- LEDs pin:
- Blue ➡ 25
- Green ➡ 26
- Red ➡ 27
- Yellow ➡ 32
- Buzzer pin ➡ 15
Code adjustment
A few parameters have to be known and set before compiling the sketch.
- SSID : WiFi network’s name
- PASSWORD : WiFi password
- APIKEY : Open weather map api key (see the references)
- CITY : e.g. “Antwerp”
- COUNTRY : e.g. “BE”
- TIMEZONE : Time zone respect to GMT e.g. 7200 for GMT+2h
const char* ssid = "SSID";
const char* password = "PASSWORD";
// Your Domain name with URL path or IP address with path (see references)
String openWeatherMapApiKey = "APIKEY";
// Replace with your country code and city
String city = "CITY"; // e.g. "Antwerp"
String countryCode = "COUNTRY"; // e.g. "BE"
unsigned long timezone = "TIMEZONE" // e.g. 7200 (GMT+2)
Blow parameters work just fine with their default values but they can be also adjusted based on your needs.
// LED indicators
#define LED_COLD 25 // pin
#define LED_NORM 26 // pin
#define LED_HOT 27 // pin
#define LED_WEATHER 32 // pin
// Set thresholds
#define TEMP_COLD 5.0 // Celsius
#define TEMP_HOT 25.0 // Celsius
#define WIND_SPEED_HIGH 30.0 // km/h
#define VISIBILITY_LOW 2.0 // km
#define HUMIDITY_HIGH 90.0 // Percent
// Define settings for buzzer
#define BUZZER_PIN 15 // pin
#define BUZZER_FRQ 2000 // Hz
#define BUZZER_CHANNEL 0 // PWM channel
// Define pins of TFT screen
#define TFT_CS 12 // pin
#define TFT_RST 14 // pin
#define TFT_DC 13 // pin
#define TFT_SCLK 22 // pin
#define TFT_MOSI 21 // pin
// Pulling time in Milliseconds (e.g. 5 min)
unsigned long timerDelay = 300000;
For more details and the sketch (C++ source code) please see https://github.com/hghcomphys/weather-monitor-module.
References
Some useful links that part of this work is based on them are as follows:
