RGB Clock

RGB Clock

The ready board for your (not only) clock projects




A 10x6cm board with 5x3 matrix of RGB LEDs driven by three DM634 chips and an Atmega328p microcontroller. Both thru-hole and SMD RGB LEDs can be used with it. All the pins are broken out, Arduino-style, and can be easily accessed. Some quick slots are added for your convenience, including an IR receiver  pins, a place for custom pullup/pulldown resistors and a small prototyping area. Two pushbuttons (one straight, one angled) are included, power is provided via a micro-USB port. The board has an RTC chip and a battery holder installed.

This board was originally designed for the RGB clock contraption, but now it’s a 5x3 RGB screen capable of displaying letters, numbers and other stuff. Sketches provided do this trick. Each base color (red, green and blue) is controlled by a separate DM634 chip on the RGB Clock board, which makes it possible to do color-correction using Global Brightness settings.

As all other UltiBlink boards, the RGB Clock has 5-pin outputs on two sides; additional extension boards can be connected to it. Check the Options tab for details.

Available colors: white.

Normal price: $26.55 + shipping

Sale price: $22.00 + FREE shipping!


Microcontroller Atmel ATmega328p @ 16MHz
LED controller 3 x DM634
LEDs supported 15 x Common anode thru-hole or SMD RGB LEDs

1 x SMD RGB LED (backside)

Operating voltage 5 V
Programming voltage 5 V
Available digital I/O pins 13 (see manual)
Available analog pins 8
Programming interfaces ISP
UART (bootloader pre-installed)
Data interfaces I2C (10K pullup resistors installed)
SPI (shared with LED drivers)
Dimensions 100 x 60 mm (±0.5 mm)

Default package contents:

1 x RGB Clock board w/battery holder(*) and microUSB power connector(**)

1 x 2x11 male pin connectors

1 x ISP 2x3 male pin connector

1 x UART 1x5 male pin connector

2 x Pushbuttons (one angled)



The board is supplied as a kit byt default. The kit includes the board itself with soldered SMD components and a set of pin headers to be soldered by yourself.
There are additional options you can select at extra cost:

Fully soldered board (no LEDs) add $2.00
SMD RGB LEDs soldered add $3.00
Female ISP header (useful if programmed using Arduino) add $0.50
Extension RGB Clock board w/o MC and clock chip $17.00

The options can be combined in any way possible, please contact me with your express wishes.

(*)CR2032 battery not included due to post-office rules. Please provide your own.
(**)The MicroUSB adaptor has Vcc and GND connections only. It cannot be used as a MicroUSB breakout board. It comes with a 1x5 male pin header for convenience; you can remove three middle pins if you want.


The RGB Clock board can not be connected to the computer directly; you’ll need a programmer, just like Arduino Pro Mini. Any generic Arduino board can act as such thanks to the Arduino ISP sketch.

There are two programming interfaces present:

- ISP (In-System Programming). The easiest way to program the RGB Clock, as you’ll just need to connect it to your Arduino following the instructions in the ArduinoISP sketch present among the pre-installed examples in the Arduino IDE. A dedicated ISP programmer can also be used, such as a USBtinyISP one.

- UART (serial). UART pinout includes the DTR line that controls an automatic reset function, the bootloader is preinstalled. You’ll need a programmer for this interface: either the dreaded FTDI or a more safe, affordable and recommended CP2102 one.

Any software capable of programming Atmel chips can be used, but I recommend the Arduino IDE to program the board, as it is easy to use and understand. In the IDE, select ‘Arduino Pro or Pro Mini’ in the Tools > Board menu, then ‘ATmega328 (5V, 16MHZ)’ in the Tools > Processor menu. If using ISP (either Arduino or a dedicated programmer) make sure to select the correct option in the Tools > Programmer menu and upload your sketches with Sketch > Upload Using Programmer option (or just Shift-click on the Upload button).

The DM63x library can be found here: https://github.com/Ontaelio/DMdriver.