Frank Vannieuwkerke / HSI2RGBW_PWM

HSI to RGB/RGBW conversion library with optional direct PWM output

Dependents:   KL25Z_HSI2RGBW_PWM KL25Z_HSI2RGBW_PWM_local KL25Z_FFT_Demo FFT_BUENA ... more

HSI to RGB / RGBW with optional PWM output

Library for converting HSI color space values to RGB or RGBW and, optionally, directly send the converted values to PWM outputs.

Code ported from http://saikoled.com - Copyright 2013, Brian Neltner
http://blog.saikoled.com/post/44677718712/how-to-convert-from-hsi-to-rgb-white

Info on the HSI color space can be found here and here.

// Dummy ISR for disabling NMI on PTA4 - !! DO NOT REMOVE THIS !!
extern "C" void NMI_Handler() {
    DigitalIn test(PTA4);
}

Demo code using the KL25Z-FRDM board:

Constructor & conversion function
When 3 PWM ouptuts are declared, the library automatically selects RGB mode.
When 4 PWM ouptuts are declared, the library automatically selects RGBW mode.
When no PWM outputs are declared, the library defaults to RGBW mode. Use .colorMode(RGB) to switch to RGB mode.
depending on the way you want to use this library, you can call the conversion function in different ways

// Assign 4 PWM outputs and also allow to return the converted RGBW value.
hsi2rgbw_pwm led(PTD4, PTA12, PTA4, PTA5);
// Call to the conversion function
float H, S, I;
float rgbw[4];
led.hsi2rgbw(H, S, I, rgbw);

// Assign 4 PWM outputs, no converted RGBW value will be returned.
hsi2rgbw_pwm led(PTD4, PTA12, PTA4, PTA5);
// Call to the conversion function
float H, S, I;
led.hsi2rgbw(H, S, I);

// No PWM outputs are assigned, only the converted RGBW value will be returned.
hsi2rgbw_pwm led(NC);
// Call to the conversion function
float H, S, I;
float rgbw[4];
led.hsi2rgbw(H, S, I, rgbw);

// Assign 3 PWM outputs and also allow to return the converted RGB value.
hsi2rgbw_pwm led(PTD4, PTA12, PTA4);
// Call to the conversion function
float H, S, I;
float rgb[4];
led.hsi2rgbw(H, S, I, rgbw);

// Assign 3 PWM outputs, no converted RGB value will be returned.
hsi2rgbw_pwm led(PTD4, PTA12, PTA4);
// Call to the conversion function
float H, S, I;
led.hsi2rgbw(H, S, I);

// No PWM outputs are assigned, only the converted RGB value will be returned.
hsi2rgbw_pwm led(NC);
//Set RGB mode
led.colorMode(RGB);
// Call to the conversion function
float H, S, I;
float rgb[4];
led.hsi2rgbw(H, S, I, rgb);

Hue, Saturation and Intesity range

RGB(W) return value
In your main program, declare an array of 4 float values and pass the pointer to this array to the function:
Even when RGB is used, do declare an array of 4 float values.

float rgbw[4];

Upon exit, the function will return the values in rgbw[], representing the red, green, blue and white component that corresponds to the chosen HSI values. Range : 0...1 where 0 = minimum and 1 = maximum.

parabolic mode
By default, each component of the RGB(W) return value is mapped to a parabolic scale.
Call led.parabolic(0); to disable the parabolic mapping.

Choose RGB or RGBW mode
By default, the conversion return value is set to RGBW.
Call led.colorMode(RGB); to change to RGB mode.
Call led.colorMode(RGBW); to go back to RGBW mode.

Change PWM period
By default, the PWM period is set to 4ms (250Hz).
Call led.period(n); to change the PWM period (replace n with a value in ms).

Change PWM values
We can alter the PWM outputs directly, without passing through the HSI to RGB(W) conversion.
declare float rgbw[4]; and set each value of this array.
Call led.pwm(rgbw); to write the values directly to the PWM outputs.

Invert PWM channels
When common anode LEDs are used, we need to invert the PWM signal..
Call led.invertpwm(1); to use the inverted PWM signal.

NOTES
period() and pwm() will not change any value if no PWM pins are declared.
Do not forget to replace led. with the declared function name.

doc error corrected.

; changed period_ms to period_us