Tag Archives: LCD

Raspberry Pi LESSON 37: Raspberry Pi Security System


 

In this lesson we add an audible alarm to our security system. I am connecting to a Bluetooth speaker, and then using the pygame library to play an alarm sound. The pygame library will play any .mp3 file, so search the internet and find a suitable alarm sound for your system. I amusing an air raid siren, and really like it! Below for your convenience is the code we develop in this video:

 

Raspberry Pi LESSON 36: Motion Detection Alarm System With LCD and Keypad

In this lesson we show the basic framework for an Alarm System with operator control through a keypad, and output to an LCD screen. We incorporate a PIR sensor to detect motion. In the next lesson we will add an audible alarm. For your convenience, the code developed in the above video is included below:

 

Creating a programmable Temperature Alarm with the Raspberry Pi

In this video lesson we show how to create a programmable temperature alarm using the Raspberry Pi, the DHT11 sensor, the ADC0834, a potentiometer and a buzzer. The results are displayed on a LCD1602 LCD display with a i2c connection. The device operates in either program mode or monitor mode. Pressing the button puts you in programming mode. In this mode you turn the potentiometer until your desired set temperature is reached. Then pressing the button again will switch you to monitor mode. In monitor mode the current temperature and humidity are displayed on the LCD. When the temperature exceeds your setpoint, the buzzer will release an audible alarm. Below is the schematic for our build.

temperature sensor
This schematic shows how to create a programmable temperature alarm

Library for I2C Connection of the LCD1602 to the Raspberry PI


This lesson shows how to connect an LCD1602 to a Raspberry Pi using only 4 wires by I2C. You will need to copy the code below, and create a program called LCD1602.py, and save it in the same folder your main python programs are in.

 

Arduino Tutorial 51: DHT11 Temperature and Humidity Sensor with LCD Display

DHT11
This shows our completed build with an Arduino Nano, LCD and DHT11 Sensor

In this lesson we work towards a stand alone Temperature and Humidity project using the DHT11 sensor.

This video will take you through the build and coding step-by-step, and the schematics below will help you follow along at home.

Our goal in this lesson is to add an LCD to the project. In lesson 50, we got the sensor working, and here we want to get the LCD connected. We are working with components from the Elegoo kit, which you can get HERE. In addition, your build can be much neater, cleaner and more stable is you use an arduino nano, instead of the standard arduino uno. The nano is small, and has male pins that allow it to be plugged directly into the breadboard, as seen above. I strongly suggest picking up an Arduino Nano, which you can get HERE. This lesson follows on to the work done in lesson 50. To recap, the DHT11 is connected as follows:

DHT11 Sensor
Connection schematic for the DHT11 Temperature Sensor.

You will also need to add the LCD, using the following schematic:

Arduino LCD Schematic
This schematic will allow you to connect the LCD to the

In my photograph at the top of the post, you can see it is important to keep the build neat, as there are lots of connections which must be made. Neat work is facilitated is you use short jumper wires, instead of the big male to male wires. You can get a jumper wire set that will keep your work neat HERE.  I am not trying to sell you a bunch of junk, but as projects get more complicated, you really need to use the short straight wires, or your build will become a rat’s nest.

We develop the code in the video in detail, but you can get the finished code down below.