ESP32 E-Paper Thermometer [UPDATED Oct. 2020]

Dear friends welcome to another project video! Today, we are going to use this small e-paper display with the ESP32 board and build a simple ESP32 E-Paper Thermometer! It is a very easy project to build. It won’t take us more than 5 minutes so let’s get started!

Intro to the ESP32 E-Paper Thermometer Project

Hello, guys, I am Nick and welcome to educ8s.tv a channel that is all about DIY electronics projects. In this channel, I share everything about the projects I build to help you develop similar projects or inspire you to start making things because it is easy, fun and creative. Subscribe to the channel now if you do not want to miss any future video.

Let’s see what we are going to build today. As you can see, I have connected a small e-paper screen to an ESP32 board. At the screen, we display the temperature which is being measured by this temperature sensor the DS18B20. The temperature reading on the screen is updated every 5 seconds. The cool thing is that we don’t refresh the whole screen which is very slow, only part of the screen which is fast and low-power! Great, the project is working fine but let’s now see how to build it!

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WHERE TO BUY
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ESP32: https://educ8s.tv/part/ESP32

E-Paper Display: https://educ8s.tv/part/EPaper154

DS18B20 Sensor: https://educ8s.tv/part/DS18B20

Small Breadboard: https://educ8s.tv/part/SmallBreadboard

Wires: https://educ8s.tv/part/Wires

Powerbank: https://educ8s.tv/part/Powerbank

Firebeetle Board: https://educ8s.tv/part/FireBeetle

Full disclosure: All of the links above are affiliate links. I get a small percentage of each sale they generate. Thank you for your support!

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A few days ago we took a first look at this small e-paper display, and we built a small project with it using an Arduino Uno board. Unfortunately, the libraries for the screen require a lot of RAM memory. The Arduino Uno offers a limited amount of memory just 2KBs so we can’t build big projects with it using this e-paper display. So we are going to use something more powerful. Actually let’s use the most powerful board we have, the ESP32.

As you can see, the ESP32 compared to an Arduino Uno is a beast! It offers two 32bit cores which operate at 160Mhz, 520KBs of RAM memory, WiFi, Bluetooth, many analog and digital pins at a price of just $7! I prepared a detailed review of the ESP32 a few months ago; you can watch it by clicking on the card here. One of the most exciting things about the ESP32 is that even though it is so powerful, it offers a deep-sleep mode which requires only 10μΑs of current. This makes the ESP32 the ideal chip for low power applications.

The E-Paper screen uses the SPI interface to communicate with the ESP32 board so we must connect it to the hardware SPI pins of the ESP32 board we use. It took me some time to find out which pins are the SPI pins on this board searching online. After I discovered them, I designed this, to save you some of your precious time.

Now that we know the pins we need all we have to do is to connect the display and the sensor to the ESP32 according to this schematic diagram. Luckily all the SPI pin are placed on the same side of this ESP32 board so we can use a breadboard to test our project. After connecting all the parts together all we have to do is to power up the project.

At first, the project displays a splash screen for 3 seconds and then it shows the temperature icon. A few moments later the temperature reading appears. The temperature reading is updated once every 5 seconds. I have also prepared a version of the code with the temperature displayed in degrees Fahrenheit for the friends of the channel living in the United States.

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LIBRARIES
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? DS18B20: https://github.com/milesburton/Arduino-Temperature-Control-Library

? GxEPD: https://github.com/ZinggJM/GxEPD

The code of the project is relatively simple. We use the great GxEPD library to drive the display and a library for the temperature sensor. At first we display the splash screen which is a bitmap file designed in Photoshop. Then we display another bitmap which is the main GUI of the project. The Wiki of the screen has detailed instructions on how to load bitmap graphics on this screen. In the loop function, we read the temperature every five seconds and we print the temperature we read on the display. We don’t refresh the whole display because it takes a lot of time, only the temperature part using the partial screen update function. As always you can find the code of the project in a link the description below.

The project works fine, and it looks great. The e-paper display is ideal for a project like this because it offers great readability and extremely low-power consumption. When the screen is not updating it needs only 0.02mAs of current! The ESP32 board needs around 60mA of current when operating. In the next video, I will try to reduce the power consumption of the project. The goal is to make this project able to run on batteries for months. To achieve that I am going to learn how to put the ESP32 to sleep to conserve power and I am going to use another ESP32 board, the Firebeetle ESP32 by DFrobot. The creators of the board claim that this board requires only 12μΑ of current in sleep mode. So, in theory, the DFrobot Firebeetle board with an E-Paper display will need only 0.03mA in sleep mode! This means that we can easily make this project last on batteries for over a year! I can’t wait to try it and share my results with you.

I would love to hear your opinion about this project. Are you going to build any project with an ESP32 and an e-paper display? Please post your ideas in the comments section below; I love reading your thoughts!

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CODE
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