How to make an IoT-based analog clock using ESP32

In this project, we’ll design an analog display clock using ESP32. The clock is an Internet-of-Things (IoT) device that retrieves the local time from a Network Time Protocol (NPT) server and displays the time (as well as the date) like an analog clock.

The display used to build this IoT clock is SSD1306. However, any display module can be used, and the code can be altered to fit within the clock’s dimensions.

Without letting any more time run out, let’s build an analog clock.

Components required

ESP32 x1
SSD1306 OLED x1
Connecting/Dupont wires

Circuit connections
To design the analog clock, we first must interface SSD1306 OLED with ESP32. The SSD1306 used in this project has a Serial Peripheral Interface (SPI) interface with the following pin diagram.

To interface the SSD1306 OLED with ESP32, follow the circuit connections as described in the below table.

The circuit diagram of the IoT-based analog clock is represented in the below image.

Arduino sketch
After making circuit connections, upload the following sketch to ESP32. Remember to replace the SSID and Wi-Fi password in the sketch with your own. Also, you might need to adjust the time to the one in your time zone.

How it works
The clock is an IoT device. As such, the microcontroller (ESP32) connects with the Internet for the current local time for the given time zone from the NTP server. POSIX is the time received, provided as seconds passed since January 1st, 1970.

The time is stored in a structure using Arduino’s time library. An analog clock is printed on the screen of the SSD1306 OLED. The hour, minute, and second hands are printed according to the current value of the time sent by the NTP server. The date and day of the week are also printed on the screen. The time is updated every second, and the screen is refreshed at the same interval.

The code
The sketch begins by importing the SPI.h, Wire.h, Adafruit_GFX.h, Adafruit_SSD1306.h, WiFi.h, and time.h libraries.

The SPI.h, Wire.h, Adafruit_GFX.h and Adafruit_SSD1306.h libraries are required to work with the SSD1306 OLED.
The WiFi.h library handles and connects with the Wi-Fi network to access the Internet.
The time.h library converts the current POSIX time into the hours, minutes, seconds, month, day, and weekday values.

This is followed by the declaration of constants and ESP32’s pin assignments with SSD1306. An object of Adafruit_SSD1306 is instantiated. The variables are declared to store the Wi-Fi SSID, Wi-Fi password, and time zone.

In the setup() function, the baud rate for serial debug messages is set to 115200 bps. The Wi-Fi connection is initialized, and the local IP address is printed to the serial console. The SSD1306 OLED display is also initialized. The connection with the NTP server is verified.

In the loop() function, the current time is retrieved from the NTP server and stored in a structure. The radius of the clock hands is set to 30 pixels. The numbers, indicating the hour ticks, are printed on the screen.

Based on the current time’s hour, minute, and second values, the hour, minute, and second hands are printed at appropriate angles on the screen. The current date and day of the week are also printed on the screen. The screen is refreshed in each loop iteration.

Results