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CIE 1931 for the LCD backlight

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This commit is contained in:
Fred Sundvik 2017-04-01 21:28:27 +03:00
parent f113f95440
commit 951b6f33a0
2 changed files with 29 additions and 6 deletions
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29
keyboards/ergodox/infinity/infinity.c
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@ -70,10 +70,33 @@ void lcd_backlight_hal_init(void) {
RGB_PORT->PCR[BLUE_PIN] = RGB_MODE;
}
static uint16_t cie_lightness(uint16_t v) {
// The CIE 1931 formula for lightness
// Y = luminance (output) 0-1
// L = lightness input 0 - 100
// Y = (L* / 902.3) if L* <= 8
// Y = ((L* + 16) / 116)^3 if L* > 8
float l = 100.0f * (v / 65535.0f);
float y = 0.0f;
if (l <= 8.0f) {
y = l / 902.3;
}
else {
y = ((l + 16.0f) / 116.0f);
y = y * y * y;
if (y > 1.0f) {
y = 1.0f;
}
}
return y * 65535.0f;
}
void lcd_backlight_hal_color(uint16_t r, uint16_t g, uint16_t b) {
CHANNEL_RED.CnV = r;
CHANNEL_GREEN.CnV = g;
CHANNEL_BLUE.CnV = b;
CHANNEL_RED.CnV = cie_lightness(r);
CHANNEL_GREEN.CnV = cie_lightness(g);
CHANNEL_BLUE.CnV = cie_lightness(b);
}
__attribute__ ((weak))