   strip.show();
 }
 
-uint32_t multiplicateBrightness(int _r, int _g, int _b) {
-  int r = (int) _r*brightness;
-  int g = (int) _g*brightness;
-  int b = (int) _b*brightness;
+uint32_t multiplicateBrightness(int _r, int _g, int _b, float _brightness) {
+  int r = (int) _r*_brightness;
+  int g = (int) _g*_brightness;
+  int b = (int) _b*_brightness;
   return strip.Color(r, g, b);
 }
 

      Serial.println(slit_position);
      updateLED();
    }
    // set brightness min value
    // "b:[0.0-1.0];"
    else if(command=="b") {
      // TODO argument check
      // argument is float
      brightness_min = argument.toFloat();
      Serial.print("set brightness min value: ");
      Serial.println(brightness_min);
      updateLED();
    }
    else {

    // sound trigger
    // "s:;"
    else if(command=="s") {
      instrument_brightness = 1.0;
      instrument_flag = !instrument_flag;
    }
    // set divide number
