Before we begin, make sure that you have the following things ready:

• A computer with an OS, such as Windows, Linux, or Mac, installed.
• An ESP32 development board. The ESP-WROVER-KIT board from Espressif is recommended.
• An ESP32 development environment configured on your computer.

• An DHT22 sensor module.
• The CoolTerm tool, which can read and write data over serial communication (UART). This is available for Windows, Linux, and Mac. We set our serial tool to the ESP32 board with Baudrate 115200.

The ESP32 chip features forty physical GPIO pads. Some GPIO pads cannot be used or do not have the corresponding pin on the chip package. For development boards based on the ESP32 chip or module, some board makers probably expose all ESP32 GPIO pins. However, some board makers also expose ESP32 GPIO pins but add additional pins such as battery, voltage, exclusive sensor, and ground.

Since there are many ESP32 development board models, we cannot explore all board models. Instead, we will focus on the ESP-WROVER-KIT board from Espressif.

We can access GPIO pins on the ESP-WROVER-KIT board with three locations. You can see these locations from the ESP-WROVER-KIT board in the following image. Some GPIO labels are shown in the board body so that we can see all of the GPIO pins:

Some GPIO pins are used for...

A weather monitoring system senses the state of the atmosphere, such as its temperature, humidity, and weather conditions (clear, stormy, and so on). To get the state of the atmosphere, we need sensors.

We can design a simple model for an IoT weather monitoring system as shown next in Figure 2-2. An IoT board with sensor devices can sense physical conditions such as temperature and humidity. Some IoT weather monitoring systems can display their sensor values on a monitor or LCD display:

Now that we've discussed the weather monitoring system and its basic architecture, let's start building our weather monitoring system. In the next section, we'll learn how to read temperature and humidity using a sensor device and an ESP32 board.

In this section, we'll build a simple program to read temperature and humidity from sensor devices. We'll use the DHT22 sensor module for this. This sensor device is easy to find on online stores such as Adafruit, SparkFun, and AliExpress.

Our project scenario is to read temperature and humidity values from a sensor device. Then, we will print sensor values on a serial Terminal. After doing this, we will implement our hardware wiring and develop a program.

Let's begin by exploring the DHT22 sensor module. This module can sense temperature and humidity. In general, the DHT22 has four pins. You can see the sensor pinout in Figure 2-3:

In this section, we will work with an LCD on ESP32 boards. This demo uses the ESP-WROVER-KIT v4 board, which has a built-in ILI9341 model LCD. You can read an ILI9341 LCD datasheet at the following link: https://cdn-shop.adafruit.com/datasheets/ILI9341.pdf.

For implementation, we will use the TFT library for ESP32. This library can be found at the following link: https://github.com/loboris/ESP32_TFT_library. Now, let's build hardware wiring for the project.

If you have the ESP-WROVER-KIT board, you don't need an additional LCD to perform hardware wiring. Otherwise, if you use another LCD module, you can connect the LCD module to the ESP32 board via ESP32 SPI pins...

In this section, we'll build a simple weather monitoring system. We'll use the skills that we've learned about, such as reading temperature and humidity from a DHT22 sensor device. Ultimately we'll be able to display the temperature and humidity on the LCD after reading from the sensor device.

Let's begin by creating a project.

To simplify our weather monitoring system project, we will copy the previous project named lcddemo and create a project called weather. Our main program is weather.c on the main folder. You can see a project structure shown in figure 2-16:

Now, let's move on to hardware...

In this chapter, we looked at a brief introduction that weather systems. Here, we made a simple ESP32 program to sense temperature and humidity using the DHT22 sensor module. Furthermore, we worked with the LCD on the ESP32 board, and were able to access the LCD modules through the ESP32 board. Lastly, we also displayed temperature and humidity data from a sensor to the LCD display. You can now compile and flash any program to your ESP32 board.

In the next chapter, we will learn how to build a simple game on an ESP32 board. We will also cover gaming-embedded systems.

To support the information that we have explored in this chapter, I recommend reading the following documents:

• ESP32 MCU datasheet document: https://www.espressif.com/en/support/download/documents/chips.
• ESP-IDF Programming Guide document: https://docs.espressif.com/projects/esp-idf/en/latest/.
• ESP-WROVER-KIT Getting Started Guide: https://docs.espressif.com/projects/esp-idf/en/latest/get-started/get-started-wrover-kit.html.