Address #1689 by using a formula to define the breathing curve (#1692)

[qmk_firmware.git] / quantum / rgblight.c

diff --git a/quantum/rgblight.c b/quantum/rgblight.c
index 0f02b9a64c7b84662caf6970d266c673008ae033..78072a61dedc593dbf3cdbe8c1b30653ec07f342 100644 (file)
--- a/quantum/rgblight.c
+++ b/quantum/rgblight.c
@@ -13,6 +13,7 @@
  * You should have received a copy of the GNU General Public License
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
+#include <math.h>
 #include <avr/eeprom.h>
 #include <avr/interrupt.h>
 #include <util/delay.h>
@@ -465,13 +466,17 @@ void rgblight_task(void) {
 void rgblight_effect_breathing(uint8_t interval) {
   static uint8_t pos = 0;
   static uint16_t last_timer = 0;
+  float val;
 
   if (timer_elapsed(last_timer) < pgm_read_byte(&RGBLED_BREATHING_INTERVALS[interval])) {
     return;
   }
   last_timer = timer_read();
 
-  rgblight_sethsv_noeeprom(rgblight_config.hue, rgblight_config.sat, pgm_read_byte(&LED_BREATHING_TABLE[pos]));
+
+  // http://sean.voisen.org/blog/2011/10/breathing-led-with-arduino/
+  val = (exp(sin((pos/255.0)*M_PI)) - RGBLIGHT_EFFECT_BREATHE_CENTER/M_E)*(RGBLIGHT_EFFECT_BREATHE_MAX/(M_E-1/M_E));
+  rgblight_sethsv_noeeprom(rgblight_config.hue, rgblight_config.sat, val);
   pos = (pos + 1) % 256;
 }
 void rgblight_effect_rainbow_mood(uint8_t interval) {