Rainbowduino, how to set luminance

Hello, I try to understand bit by bit, how the Rainbowduino shield works.
I don’t want to control the board over I2C, I will learn to program it directly.

On the sketches I understood, I have to fill shift latches over two output pins, and I have to switch otuputs for the LED driver. But I don’t understand how I have to control the power of the leds. Have I make a PWM on the outputs? What is the right way? The default programs are very difficult to understand for me. I am not able to read the function in it.

by the way are there more technical ressources for the Rainbowduino? I found only the PCB and the SCH and a very short pdf which shows the function of the demo progs.

Regards Randolf Balasus

Sadly there are not too many written manuals or resources,
what do you really want to do?
If you just want to set the power of the leds you can send a command with 0 to 15 setting the value of the color,
also you have the posibility of controlling the intensity of every color with an small potentiometer in the board,
this last option modifies the current for the particular color in all the eleds in the matrix

First of all many thanks for the answer.
Yes I have seen in the demo application, that there is a value 0-15 for the power.
But now I try to programm the rainbowduino by myself. I have seen three latches, for the three 8er groups of LED und I have seen 8 GPIO for the othe side of those LED. And now I don’t knoww how do I have to applicate there a useful solution to control the power of the LED.

Regards Randolf Balasus

The hardware can only switch the LEDs on and off. To control the brightness you need to use Pulse Width Modulation in software. This is what the demo application does, the interrupt service routine uses the brightness value 0-15 to control the amount of time each LED is switched on for.