Kindly Morrow
DS1302 LED Dot Matrix Clock DIY Kit - Soldering Practice
Solder your first real-time clock and have a working, programmable display on your desk by the end of the session. The DS1302 RTC keeps ticking through power loss via its onboard backup battery, so your time data survives every reset. The LED dot matrix is fully yours to program: fonts, scroll speed, animations, whatever you want to push to it.
All components are through-hole, which means clean solder joints are achievable even on your first attempt. Communication between the DS1302 and your Arduino runs over a 3-wire SPI-like interface (CE, I/O, SCLK), and the example code walks you through reading and writing registers directly. Compatible with Arduino Uno, Nano, and any 5V-compatible AVR board you have on hand.
Things to build with this
- Use the DS1302's alarm register (byte 0x8F) to trigger a GPIO output at a set time and drive a buzzer or relay, giving you a hardware alarm that fires without any loop-based polling in your sketch
- Write a frame buffer to the dot matrix and update it on a 1-second DS1302 interrupt, displaying a custom animation sequence that advances with each tick rather than using delay()
- Program the matrix to render a Pomodoro countdown by reading elapsed seconds from the DS1302 registers and mapping the remaining time to a shrinking bar graphic across the 8x8 grid
Key Features
- DS1302 RTC: 3-wire serial interface, trickle-charge backup battery keeps time through power loss
- LED dot matrix display: fully programmable via Arduino IDE for custom fonts, scrolling text, and frame animations
- Through-hole components only: resistors, capacitors, discrete LEDs, and DIP ICs throughout
- Schematic and component list included: read the circuit before you solder it
- Arduino example code included: covers RTC register read/write and basic matrix rendering
- Works with Arduino Uno, Nano, and 5V AVR-compatible boards
- Modular layout: easy to trace signals and modify the circuit as your skills build
Frequently Asked Questions
Does the clock keep time when the Arduino is unplugged?
Yes. The DS1302 has a backup battery input (typically a CR2032 coin cell) that keeps the RTC running independently of your main power supply. You will need to supply the coin cell yourself as it is not always included in base kits.
Do I need to write the code from scratch?
No. The kit includes basic Arduino example code that covers initializing the DS1302, reading the current time, and sending characters to the dot matrix. You can run it as-is first, then modify it once you see how the register writes work.
What library does this use for the dot matrix?
Most builds use either the LedControl library or direct bit-banging through the MAX7219 driver (if your matrix module includes one). Check whether your matrix module has a MAX7219 onboard. If it does, LedControl makes scrolling text straightforward.
Is this suitable for someone who has never soldered before?
Yes, that is the point. Every joint in this kit is through-hole, which gives you a lead to hold the component in place while you apply heat. Pads are spaced generously and there are no surface-mount components to worry about.
Why we stock this
Curated by Kindly Morrow. We test and vet every product before it hits the store. If we wouldn't use it in our own builds, we don't sell it.
Things to build with this
Fun projects to try once you get your hands on it.
Weather station that texts you
Hook up a temperature sensor and have it send you a Telegram message when it drops below freezing. 20 lines of MicroPython.
Garage door opener you control from bed
Wire a relay to your garage door motor and trigger it from your phone via Home Assistant. No cloud, no subscription.
Plant watering system that knows when to water
Soil moisture sensor + a small pump. Runs on a schedule or when the soil gets dry. Your plants stop dying.
Desk presence sensor for smart lighting
mmWave or PIR sensor detects when you sit down and turns on your desk lights. Turns them off when you leave. Zero effort after setup.
