This desktop watch shows the current time and the humidity. It has a temperature compensated real time clock. With two buttons it is possible to set up the hours and the minutes. It needs continuous power supply, but in case of blackout the clock has an UPS. After the power will come again no need to setup the time. It measures the sun light with a photo resistor. In case of darkness the intensity of the display gets lower, in case of intensive sun light it gets brighter. The temperature can be also displayed at the lower row (it needs program change). The device needs external power a standard mobile 5V AC/DC adapter will do the task.
Step 1: BOM List
1 pc. DHT22/AM2302
Digital Temperature And Humidity Sensor Module
1 pc. Pro Mini Microcontroller Circuit Board for Arduino (5V / 16MHz)
2 pcs. 4 Bits Digital Tube LED Display Module With Clock Display TM1637 for Arduino
2 pcs 6k8 1/4W Resistance Metal Film Resistors
1 pc 2k2 1/4W Resistance Metal Film Resistors
2 pcs. Momentary SPST NO Red Round Cap Push Button Switch AC 6A/125V 3A/250V
1 pc. 5MM Photoresistor GL5537 LDR Photo Resistors Light-Dependent
1 pc. 230VAC/5VDC adapter
25 pcs Breadboard Jumper Cable Wires
5 pcs wood screw 3mm
1 pc. box
Optional soldering station (it is possible to do it without soldering, but than it is needs bigger box and bread board)
Step 2: Build the Unit
Find the right box for the project, I choose a small wooden box, originally bought as a jewellery box. Use drill to install all components on/in the box. I did not fix the Arduino board to the box, because so I found easier to handle cables. Apply screws to fix the modules to the box. Instead of screw you can use glue. Cable all the components according to the schematic. I used a mixture of soldering and jumper connection and no breadboard, because of the small available space.
Step 3: Software
Upload the attached software.
For uploading or changing the code download and install Arduino Software.
Use a Crius FTDI Basic Breakout 5V USB to TTL 6-Pin Module for MWC MultiWii Lite module (other downloader could also work), to connect the PC to the Arduino.
I used the following libraries. Thanks for them. Before using this software check their licencing: