Frank Vannieuwkerke
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.
KL25Z PTA4 as PWM output
By default, PTA4 is defined as the NMI input in the the mbed library. When PTA4 is to be used as a PWM output, we MUST disable the NMI assignment, otherwise the system will lock-up when this pin is pulled low. Read this page for more information.
The easiest way (without changing mbed-src) to disable the NMI input is by adding following code at the start of your main program (this is present in the demo program mentioned below):
// 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:
Import programKL25Z_HSI2RGBW_PWM
SaikoLED fade demo using the HSI2RGBW_PWM libary
Last commit 02 Feb 2014 by 
Frank Vannieuwkerke
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
Hue | 0...360 | Color value : 0 or 360 = red, 120 = green, 240 = blue, 60 = yellow, 300 = magenta, ... |
Saturation | 0...1 | Color saturation : 0 = white, 1 = max. color, 0.7 is a nice pastel |
Intensity | 0...1 | Color intensity : 0 = off, 1 = full intensity |
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.
| rgbw[0] | RED | |
| rgbw[1] | GREEN | |
| rgbw[2] | BLUE | |
| rgbw[3] | WHITE | Note : this value has no significance when RGB mode is used. |
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.
Diff: hsi2rgbw_pwm.h
- Revision:
- 0:dd0e7a8a4572
- Child:
- 1:191c9b17351c
diff -r 000000000000 -r dd0e7a8a4572 hsi2rgbw_pwm.h
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/hsi2rgbw_pwm.h Mon Dec 23 20:24:17 2013 +0000
@@ -0,0 +1,116 @@
+/**************************************************************************************************************
+ ***** *****
+ ***** Name: hsi2rgbw.h *****
+ ***** Date: 22/12/2013 *****
+ ***** Auth: Frank Vannieuwkerke *****
+ ***** Func: library for converting HSI color space values to RGBW *****
+ ***** *****
+ ***** Code ported from http://saikoled.com - Copyright 2013, Brian Neltner *****
+ ***** http://blog.saikoled.com/post/44677718712/how-to-convert-from-hsi-to-rgb-white *****
+ ***** http://blog.saikoled.com/post/43693602826/why-every-led-light-should-be-using-hsi-colorspace *****
+ ***** https://github.com/saikoLED/MyKi/blob/master/myki_16_bit_random_fade/myki_16_bit_random_fade.ino *****
+ ***** https://github.com/saikoLED/MyKi/blob/master/myki_16_bit_fade/myki_16_bit_fade.ino *****
+ ***** *****
+ ***** This program is free software: you can redistribute it and/or modify *****
+ ***** it under the terms of the GNU General Public License as published by *****
+ ***** the Free Software Foundation, version 3 of the License. *****
+ ***** *****
+ ***** This program is distributed in the hope that it will be useful, *****
+ ***** but WITHOUT ANY WARRANTY; without even the implied warranty of *****
+ ***** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *****
+ ***** GNU General Public License for more details. *****
+ ***** *****
+ ***** A copy of the GNU General Public License can be found at *****
+ ***** http://www.gnu.org/licenses/gpl.html *****
+ **************************************************************************************************************/
+
+#include "mbed.h"
+
+#ifndef HSI2RGBW_PWM_H
+#define HSI2RGBW_PWM_H
+
+#define RGBW 1
+#define RGB 0
+
+/** Class to convert HSI colorspace value to its corresponding RGBW value.
+* 'red', 'green', 'blue' and 'white' pin can be any PWM pin.
+*/
+
+class hsi2rgbw_pwm {
+public:
+ /** Create a HSI2RGBW object connected to 4 PWM pins.
+ *
+ * @param red = RED PWM pin\n
+ * @param blue = BLUE PWM pin\n
+ * @param green = GREEN PWM pin\n
+ * @param white = WHITE PWM pin\n
+ * @return none\n
+ * When you want to use hsi2rgbw standalone (no PWMout), use following initializer:\n
+ * hsi2rgbw_pwm led; OR hsi2rgbw_pwm led(NC, NC, NC, NC);\n
+ * Create a float array in your program to return the rgbw values, eg : float rgbw[4]\n
+ * Call hsi2rgbw with the rgbw pointer : hsi2rgbw(H, S, I, rgbw)\n
+ */
+ hsi2rgbw_pwm(PinName red = NC, PinName green = NC, PinName blue = NC, PinName white = NC);
+
+ /** Convert HSI to RGBW or RGB.
+ *
+ * @param Hue = float (0..1)\n
+ * @param Saturation = float (0..1)\n
+ * @param Intensity = float (0..1)\n
+ * @param rgbw = Optional pointer to float array[4]\n
+ * This parameter can be omitted when PWM output is enabled:\n
+ * hsi2rgbw(H, S, I)\n
+ * This function can be used to convert HSI to RGBW or RGB:\n
+ * call colorMode(RGBW) to enable HSI->RGBW\n
+ * call colorMode(RGB) to enable HSI->RGBW\n
+ * IMPORTANT NOTE : When RGB is selected and you want the function to return\n
+ * the converted value, do declare a 4 element array!!\n
+ * The value in the 4th element can be discarded.\n
+ */
+ void hsi2rgbw(float H, float S, float I, float* rgbw = NULL);
+
+ /** Change PWM period.
+ *
+ * @param Period (in ms)\n
+ * @return none\n
+ */
+ void period(uint32_t per);
+
+ /** Change PWM value.
+ *
+ * @param pointer to float array[4]\n
+ * @param array[0] = RED PWM value (0...1)\n
+ * @param array[1] = BLUE PWM value (0...1)\n
+ * @param array[2] = GREEN PWM value (0...1)\n
+ * @param array[3] = WHITE PWM value (0...1)\n
+ * Use this function to set the PWM values without conversion.\n
+ * @return none\n
+ */
+ void pwm(float* rgbw);
+
+ /** Set parabolic mode.
+ *
+ * @param Parabolic : 1 = map rgbw output value to a parabolic curve (default).\n
+ * 0 = linear mapping.\n
+ * @return none\n
+ */
+ void parabolic(bool para);
+
+ /** Set color conversion mode.
+ *
+ * @param Colormode : RGBW (1) = convert HSI to RGBW (default).\n
+ * RGB (0) = convert HSI to RGB.\n
+ * @return none\n
+ */
+ void colorMode(bool como);
+
+private:
+ PwmOut _red;
+ PwmOut _green;
+ PwmOut _blue;
+ PwmOut _white;
+ bool parabol;
+ bool use_pwm;
+ bool use_rgbw;
+};
+#endif