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Step 4You've got to have some code!
In high brightness mode the board supports 6 different colors + white. The color is chosen by setting 3 GPIO pins to high or low. That way all eight LEDs can be fully on, but only show the same color.
In PWM mode the color is set by applying a pulse width modulated signal the the 3 GPIO pins and multiplexing the 8 LEDs. This reduces overall brightness, but now individual color control is possible. This is done in the background by an interrupt routine. Basic functions are available for setting the LEDs a certain color value, either using an RGB triplet or a HUE value.
The device is programmed in C using the Arduino IDE for convenience. I've attached the current code I use. Up to date versions are available on my blog. You can browse the GIT repository using the gitweb interface. Many stupid programming mistakes will show up, I'm sure of it ;-)
The second figure illustrates PWM generation. A hardware counter counts from BOTTOM to TOP. Once the counter is larger than a certain number representing a desired color, the output is toggled. Once the counter has reached its TOP value, everything is reset. The perceived brightness of the LED is somewhat proportional to the on-time of the signal. Strictly speaking that's a lie, but easier to understand.
In PWM mode the color is set by applying a pulse width modulated signal the the 3 GPIO pins and multiplexing the 8 LEDs. This reduces overall brightness, but now individual color control is possible. This is done in the background by an interrupt routine. Basic functions are available for setting the LEDs a certain color value, either using an RGB triplet or a HUE value.
The device is programmed in C using the Arduino IDE for convenience. I've attached the current code I use. Up to date versions are available on my blog. You can browse the GIT repository using the gitweb interface. Many stupid programming mistakes will show up, I'm sure of it ;-)
The second figure illustrates PWM generation. A hardware counter counts from BOTTOM to TOP. Once the counter is larger than a certain number representing a desired color, the output is toggled. Once the counter has reached its TOP value, everything is reset. The perceived brightness of the LED is somewhat proportional to the on-time of the signal. Strictly speaking that's a lie, but easier to understand.
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