Tobi’s Corner

What can you do with 100 common anode rgb leds? build a 8×8 matrix and interface it!

The circuit uses 74HC595 shift registers with output latch. each shiftregister interfaces one color + one shiftreg for the matrix rows. the interfaces uses 6 I/O lines for faster speed and easier interfacing. an avr running at 8MHz can update the matrix with 8 brightness levels displaying nice fading colors patterns or colored text (or both). the sample program creates fading color patterns using a sine table. for smoother display a double buffer was implemented.

Download: rgbmatrix.c

Part List: (more…)

Here you can see my IKEA Storm Lamp Mod using the powerRGB circuit and the tinyRGB firmware.

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powerRGB is the extension of tinyRGB to drive high power LED’s. For this project I used a 3 x 1W common Anode RGB LED.

Q1 to Q3 are N-Channel HEXFet Mosfet’s with logic level drive and a RDSon at about 50mOhms. R1 to R3 are at about 2k2, R4 to R6 at about 15k and R7 to R9 depend on the LED used and VCC. If you use FET’s with higher RDSon you have to consider RDS in your calculation!

Rx = (Vcc-Vf)/Im - RDSon

[Vcc: Volatge of power supply, Vf: Vorward Voltage of the Diode, Im: Max current of LED]

The software for the AVR is the same as for tinyRGB.

avrDotmatrix uses a 5×7 dotmatrix display and an ATMega8 to create a nice display with scrolling!

avrDotmatrix - Is a 5×7 LED Matrix Display controlled by a ATMega8 to display scrolling text, time or temperatures. The pattern is generated with multiplexing the 5 matrix columns and setting the correct row bits.

This projects is still in development and i’m gonna add a temperature sensor (LM75), a I2C EEProm and maybe a IR receiver for transmitting texts to the display wireless.

Downloads:

• Sample Video
• avrDotmatrix Sourcecode