Hello!

I want to introduce you to one of the first Raspberry Pi projects, and the next project I will present aims to teach you how to use certain components together with a Raspberry Pi platform. I started learning a few commands in Python (if statements, for or while loops), then, slowly I made the first assembly with a Raspberry Pi and an LED and a resistor. Later, I added other components, which I had in my office drawer; it would be useful for me to have an LCD display (with I2C it's even better) to display some text messages on it; a DHT11 module that measures the temperature and humidity in the room I was in. To carry out this project, I searched the internet for information on how to use the ports on the Raspberry Pi, how to use an LCD display with I2C, or how to use a DHT11 module; then, slowly, I tried to make them work together.

I started using an LED, and found some information; thus, it is necessary to write some commands in the Terminal Window window (as in Figure 1):

sudo apt-get update

sudo apt-get upgrade

sudo apt-get install python3-pip

sudo pip3 install --upgrade setuptools

We enter the commands one by one, after each command we press Enter and wait for the action to be completed.

Figure 1

You can also access the following link for more information https://learn.adafruit.com/circuitpython-on-raspberrypi-linux/installing-circuitpython-on-raspberry-pi .

In order to use a DHT11 module, it is necessary to write some commands again in Terminal Window (Figure 2):

pip3 install adafruit-circuitpython-dht

sudo apt-get install libgpiod2

We enter the commands one by one, after each command we press Enter and wait for the action to be completed.

Figure 2

You can also access the following link for more information https://learn.adafruit.com/dht-humidity-sensing-on-raspberry-pi-with-gdocs-logging/python-setup .

Now, we are going to configure the LCD display with I2C interface.

You must enable I2C communication; in Terminal Window we type the command:

sudo raspi-config

The window will open:

Figure 3

Select Interface Options:

Figure 4.

Then I have to enable I2C and press Finish.

From us, in Terminal Wndows we write the following commands:

sudo apt-get install i2c-tools    

sudo apt-get install python-smbus

Now, we need to connect the LCD display with the I2C interface to the Raspberry Pi, I am attaching an image to help us:

Figure 5.

Now, connect the I2C LCD to the Raspberry Pi according to the diagram below:

Figure 6.

The SDA pin from the I2C LCD connects to the physical pin no. 3 on the Raspberry Pi platform (GPIO2, which has the SDA function), and the SCL pin from the LCD I2C connects to the physical pin no. 5 (GPIO3, which has the SCL function)

After making the connections, in Terminal Window we write the command below to find the address of our I2C mode (for me it is 0x27):

i2cdetect -y 1.

Figure 7

Now we need to write a code in a file (as the program is too long, I attach this link where you can copy the program https://www.circuitbasics.com/raspberry-pi-i2c-lcd-set-up-and -programming /). Copy the program to Thonny and save the file named I2C_LCD_driver. Don't forget to write to ADDRESS = 0x27 the address from your I2C. Also at this link, you can find some example programs, very useful for a beginner like me.

These are the necessary settings for the project I am going to present to you.

The electronic scheme in which I use a Raspberry Pi, a DHT 11 module, an I2C LCD display and two LEDs, is as follows (Figure 8):

Figure 8.

I recommend using a separate power supply for the I2C LCD, DHT11 (don't forget the ground wire).

This project displays temperatures in degrees Celsius and humidity measured with a DHT11 on an LCD display with I2C interface; also, use two LEDs, if the temperature is higher than 25 degrees Celsius, it means that the room is quite warm and the red indicator light lights up. If the temperature in the room is lower than 25 degrees Celsius, it means that it is good and the green LED lights up.

I hope you enjoyed this little tutorial.

And, the physically made circuit looks like this:

Figure 9

The program can also be run in Thonny, by pressing Run, or in Terminal Window.

Copy the program to Thonny and save the file with any name you want. An important aspect, in order to be able to use the I2C LCD display in this project, these two files must be in the same directory.

Thanks to the PCBWay team!