86 lines
3.5 KiB
C
86 lines
3.5 KiB
C
/*
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The MIT License (MIT)
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Copyright (c) 2016 Fred Sundvik
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Permission is hereby granted, free of charge, to any person obtaining a copy
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of this software and associated documentation files (the "Software"), to deal
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in the Software without restriction, including without limitation the rights
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to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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copies of the Software, and to permit persons to whom the Software is
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furnished to do so, subject to the following conditions:
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The above copyright notice and this permission notice shall be included in all
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copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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SOFTWARE.
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*/
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#include "lcd_backlight.h"
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#include <math.h>
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static uint8_t current_hue = 0x00;
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static uint8_t current_saturation = 0x00;
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static uint8_t current_intensity = 0xFF;
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static uint8_t current_brightness = 0x7F;
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void lcd_backlight_init(void) {
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lcd_backlight_hal_init();
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lcd_backlight_color(current_hue, current_saturation, current_intensity);
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}
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// This code is based on Brian Neltner's blogpost and example code
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// "Why every LED light should be using HSI colorspace".
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// http://blog.saikoled.com/post/43693602826/why-every-led-light-should-be-using-hsi
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static void hsi_to_rgb(float h, float s, float i, uint16_t* r_out, uint16_t* g_out, uint16_t* b_out) {
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unsigned int r, g, b;
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h = fmodf(h, 360.0f); // cycle h around to 0-360 degrees
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h = 3.14159f * h / 180.0f; // Convert to radians.
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s = s > 0.0f ? (s < 1.0f ? s : 1.0f) : 0.0f; // clamp s and i to interval [0,1]
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i = i > 0.0f ? (i < 1.0f ? i : 1.0f) : 0.0f;
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// Math! Thanks in part to Kyle Miller.
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if(h < 2.09439f) {
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r = 65535.0f * i/3.0f *(1.0f + s * cos(h) / cosf(1.047196667f - h));
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g = 65535.0f * i/3.0f *(1.0f + s *(1.0f - cosf(h) / cos(1.047196667f - h)));
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b = 65535.0f * i/3.0f *(1.0f - s);
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} else if(h < 4.188787) {
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h = h - 2.09439;
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g = 65535.0f * i/3.0f *(1.0f + s * cosf(h) / cosf(1.047196667f - h));
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b = 65535.0f * i/3.0f *(1.0f + s * (1.0f - cosf(h) / cosf(1.047196667f - h)));
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r = 65535.0f * i/3.0f *(1.0f - s);
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} else {
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h = h - 4.188787;
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b = 65535.0f*i/3.0f * (1.0f + s * cosf(h) / cosf(1.047196667f - h));
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r = 65535.0f*i/3.0f * (1.0f + s * (1.0f - cosf(h) / cosf(1.047196667f - h)));
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g = 65535.0f*i/3.0f * (1.0f - s);
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}
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*r_out = r > 65535 ? 65535 : r;
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*g_out = g > 65535 ? 65535 : g;
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*b_out = b > 65535 ? 65535 : b;
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}
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void lcd_backlight_color(uint8_t hue, uint8_t saturation, uint8_t intensity) {
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uint16_t r, g, b;
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float hue_f = 360.0f * (float)hue / 255.0f;
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float saturation_f = (float)saturation / 255.0f;
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float intensity_f = (float)intensity / 255.0f;
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intensity_f *= (float)current_brightness / 255.0f;
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hsi_to_rgb(hue_f, saturation_f, intensity_f, &r, &g, &b);
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current_hue = hue;
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current_saturation = saturation;
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current_intensity = intensity;
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lcd_backlight_hal_color(r, g, b);
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}
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void lcd_backlight_brightness(uint8_t b) {
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current_brightness = b;
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lcd_backlight_color(current_hue, current_saturation, current_intensity);
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}
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