- A standalone arduino / Arduino Pro Mini
- 60 White LEDs – 5mm
- 9 resistors – 110 Ω
- WS2812B RGB LED strip - 60 LEDs
- RTC Module – DS1307
- Some headers, wires, capacitors, etc
- 12V – 800mA adapter
- CP2102 USB-to-TTL (the RST pin on the CP2102 is not for resetting the arduino – you have to solder a wire to the DTR pad on the PCB – which sends a reset signal to program the arduino. This has to be connected to the reset pin through a 104 capacitor) or Arduino to program the standalone processor as discussed in the previous post.
The Circuit is built in two steps:
- Take a strip board and connect the LEDs as per the table above. Please note, the LED numbers in blue were soldered by mistake and I had to modify the code to correct for this
- I suggest you leave a blank row between the LED rows - this would make the circuit simpler and easier to troubleshoot
- I used thin resin-covered copper wires to make this circuit as you can see below, however have been advised that ethernet cable would be a better option
Arduino Circuit with the WS2812B RGB LEDs and RTC
- SDA and SCL pins to the RTC module’s SDA and SCL pins.
- PIN 12 to data pin of the WS2812B LED strip
- PINs 3-11 to the Charlieplexed LEDs as above
Make sure you connect the power adapter directly to the RGB LED strip and not through the arduino. The code ensures that the white LEDs do not glow all at the same time, please do not modify, as switching on all the white LEDs may damage your arduino.
I use the following libraries:
Code can be found at:
For the clock-face I pulled out one of my photographs from Singapore and modified it to suit a clock face. I got this printed on photographic paper.
- Cut a piece of thick solid cardboard into a circle with a diameter of 318.3 mm. Please note, the circumference of the clock HAS to be 1 meter for the LED strip to fit perfectly
- Stick the LED strip on the circumference, with the first LED at the 12 o'clock position
- Stick the white LEDs behind each of the RGB LEds on the strip (as below)
- Stick the clock face from the previous step on the cardboard circle