In the manufacture of this device, the master set himself the following tasks:
-autonomy when a power outage;
-informativity;
- backlight;
Some displayed parameters and settings: time, date, calendar with the function of displaying holidays, temperature, color change depending on temperature, humidity, voltage and battery power, the ability to calibrate and some others. A 450 mAh lithium battery is installed on the device, allowing you to work offline for up to 9 hours.
Tools and materials:
-Arduino:
- TP4056 charging module;
-LCD display ST7735;
-KY-040 rotation sensor module (encoder);
- Temperature and humidity sensor DHT22 AM2302;
- DS1307 module (real-time clock with I2C interface and EEPROM memory chip on 32K bit);
- Microcontroller ATmega328P;
-Lipo battery 3.7V 450mAh;
-6-pin 2-position slide switch DPDT;
- Battery CR2032;
- Printed-circuit board 10x22 cm;
-Connectors;
-Acrylic;
-Soldering accessories;
-Knife;
-Cardboard;
-Glue;
-Computer with software;
-Tweezers;
-Rule;
-Pencil;
Step One: Project
First, the master develops the project. Determined with the shape and material of the case. It works out what information should be displayed. The front panel will have a display with an encoder, the RTC module on the right, and the DHT module on the left. The top and bottom are transparent. At the top is a battery and a slide switch.
Step Two: Scheme
Further, the author is working on a device diagram.
You can find out more about pinout by downloading the following file.
Step Three: About Battery
The project uses a battery with a capacity of 450 mAh, which holds a charge of about 9 hours. In standby mode, the device consumes 0.102A. When the button is pressed, the consumption is 0.177A.
Step Four: Display
According to the scheme using the SPI bus connects the display. The instructions for the screen can be found below.
Step Five: DS1307 Module
This module is powered by the rechargeable LIR2032 battery by default, but it is difficult to find such a battery, and the master replaced it with a regular CR2032. The module needs to be slightly redone by removing the charging components from the board.You need to remove the diodes D1, R4, R5 and R6, and then the contacts R6 must be connected by wire. Details on how to do this can be seen by clicking on this.
Step Six: The Case
Panel cuts out of cardboard. The panel cuts a window under the screen. Fixes the screen and encoder.
From acrylic cuts panels for the bottom and top.
Glues the side walls. Cut a hole for the battery in the right wall and for the temperature and humidity sensor in the left.
Seventh step: assembly
According to the scheme, it connects arduino, display, time module.
Connects a temperature and humidity module, a battery, a slide switch.
The code can be downloaded.
Installs the top cover.
Checks the operation of the device.
Step Eight: Calibration
The master calibrated using an air conditioner and thermometers.
The thermometer is ready.
As can be seen from the photos, the device shows everything as the author intended. The thermometer turned out to be quite informative. True, the design let us down, but our readers can improve it and make it in a beautiful, convenient case.