diff --git a/include/hsv2rgb.h b/include/hsv2rgb.h
new file mode 100644
index 0000000..2b36f5c
--- /dev/null
+++ b/include/hsv2rgb.h
@@ -0,0 +1,98 @@
+#ifndef _INC_HSV2RGB_H
+#define _INC_HSV2RGB_H
+
+
+
+#include <stdint.h>
+
+
+typedef struct color_rgb {
+	uint8_t r;
+	uint8_t g;
+	uint8_t b;
+} color_rgb;
+
+typedef struct color_hsv {
+	int16_t h;
+	uint8_t s;
+	uint8_t v;
+} color_hsv;
+
+
+#define HSV_HUE_SEXTANT		256
+#define HSV_HUE_STEPS		(6 * HSV_HUE_SEXTANT)
+
+#define HSV_HUE_MIN			0
+#define HSV_HUE_MAX			(HSV_HUE_STEPS - 1)
+#define HSV_SAT_MIN			0
+#define HSV_SAT_MAX			255
+#define HSV_VAL_MIN			0
+#define HSV_VAL_MAX			255
+
+/* Options: */
+#define HSV_USE_SEXTANT_TEST	/* Limit the hue to 0...360 degrees */
+
+
+void hsv2rgb_8b(int16_t h, uint8_t s, uint8_t v, uint8_t *r, uint8_t *g , uint8_t *b);
+
+
+/*
+ * Macros that are common to all implementations
+ */
+#ifdef HSV_USE_SEXTANT_TEST
+#define HSV_SEXTANT_TEST(sextant) \
+	if((sextant) > 5) { \
+		(sextant) = 5; \
+	}
+
+#else
+#define HSV_SEXTANT_TEST(sextant)
+#endif
+
+/*
+ * Pointer swapping:
+ * 	sext.	r g b	r<>b	g<>b	r <> g	result
+ *	0 0 0	v u c			!u v c	u v c
+ *	0 0 1	d v c				d v c
+ *	0 1 0	c v u	u v c			u v c
+ *	0 1 1	c d v	v d c		d v c	d v c
+ *	1 0 0	u c v		u v c		u v c
+ *	1 0 1	v c d		v d c	d v c	d v c
+ *
+ * if(sextant & 2)
+ * 	r <-> b
+ *
+ * if(sextant & 4)
+ * 	g <-> b
+ *
+ * if(!(sextant & 6) {
+ * 	if(!(sextant & 1))
+ * 		r <-> g
+ * } else {
+ * 	if(sextant & 1)
+ * 		r <-> g
+ * }
+ */
+#define HSV_SWAPPTR(a,b)	do { uint8_t *tmp = (a); (a) = (b); (b) = tmp; } while(0)
+#define HSV_POINTER_SWAP(sextant,r,g,b) \
+	do { \
+		if((sextant) & 2) { \
+			HSV_SWAPPTR((r), (b)); \
+		} \
+		if((sextant) & 4) { \
+			HSV_SWAPPTR((g), (b)); \
+		} \
+		if(!((sextant) & 6)) { \
+			if(!((sextant) & 1)) { \
+				HSV_SWAPPTR((r), (g)); \
+			} \
+		} else { \
+			if((sextant) & 1) { \
+				HSV_SWAPPTR((r), (g)); \
+			} \
+		} \
+	} while(0)
+
+
+
+#endif /* _INC_HSV2RGB_H */
diff --git a/include/rgbprog.h b/include/rgbprog.h
new file mode 100644
index 0000000..9a5b281
--- /dev/null
+++ b/include/rgbprog.h
@@ -0,0 +1,16 @@
+/*
+ * rgbprog.h: making your eyes light up
+ *
+ * file creation: 20231021 2338
+ */
+
+#ifndef _INC_RGBPROG_H
+#define _INC_RGBPROG_H
+
+
+
+void rgbprog_run();
+
+
+
+#endif /* _INC_RGBPROG_H */
\ No newline at end of file
diff --git a/include/userio.h b/include/userio.h
index 103758d..2f64924 100644
--- a/include/userio.h
+++ b/include/userio.h
@@ -30,6 +30,7 @@ extern uint8_t knob[2];
 void userio_parse();
 
 uint8_t userio_get_mode();
+int16_t userio_get_btn();
 
 
 
diff --git a/src/hsv2rgb.c b/src/hsv2rgb.c
new file mode 100644
index 0000000..45bab96
--- /dev/null
+++ b/src/hsv2rgb.c
@@ -0,0 +1,94 @@
+/*
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2016  B. Stultiens
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+
+#include "hsv2rgb.h"
+
+
+void hsv2rgb_8b(int16_t h, uint8_t s, uint8_t v, uint8_t *r, uint8_t *g , uint8_t *b)
+{
+	uint8_t sextant;
+	uint8_t bb;
+	uint16_t ww;
+	uint8_t h_fraction;
+
+	if (!(s)) {
+		*(r) = *(g) = *(b) = (v);
+		return;
+	}
+
+	sextant = h >> 8;
+	HSV_SEXTANT_TEST(sextant);			// Optional: Limit hue sextants to defined space
+
+	HSV_POINTER_SWAP(sextant, r, g, b);	// Swap pointers depending which sextant we are in
+
+	*g = v;		// Top level
+
+	// Perform actual calculations
+	/*
+	 * Bottom level: v * (1.0 - s)
+	 * --> (v * (255 - s) + error_corr) / 256
+	 */
+	bb = ~s;
+	ww = v * bb;
+	ww += 1;		// Error correction
+	ww += ww >> 8;		// Error correction
+	*b = ww >> 8;
+
+	h_fraction = h & 0xff;	// 0...255
+
+	if(!(sextant & 1)) {
+		// *r = ...slope_up...;
+		/*
+		 * Slope up: v * (1.0 - s * (1.0 - h))
+		 * --> (v * (255 - (s * (256 - h) + error_corr1) / 256) + error_corr2) / 256
+		 */
+		ww = !h_fraction ? ((uint16_t)s << 8) : (s * (uint8_t)(-h_fraction));
+		ww += ww >> 8;		// Error correction 1
+		bb = ww >> 8;
+		bb = ~bb;
+		ww = v * bb;
+		ww += v >> 1;		// Error correction 2
+		*r = ww >> 8;
+	} else {
+		// *r = ...slope_down...;
+		/*
+		 * Slope down: v * (1.0 - s * h)
+		 * --> (v * (255 - (s * h + error_corr1) / 256) + error_corr2) / 256
+		 */
+		ww = s * h_fraction;
+		ww += ww >> 8;		// Error correction 1
+		bb = ww >> 8;
+		bb = ~bb;
+		ww = v * bb;
+		ww += v >> 1;		// Error correction 2
+		*r = ww >> 8;
+
+		/*
+		 * A perfect match for h_fraction == 0 implies:
+		 *	*r = (ww >> 8) + (h_fraction ? 0 : 1)
+		 * However, this is an extra calculation that may not be required.
+		 */
+	}
+}
diff --git a/src/led.c b/src/led.c
index 0547b89..563d77b 100644
--- a/src/led.c
+++ b/src/led.c
@@ -47,9 +47,9 @@ void led_next()
 
 	if (!led_sel || (led_mode == MODE_RGB)) {
 		// set PWMs in RGB mode, or when right LED set
-		PWM_RGB_R = rgb[led_sel][RED];
-		PWM_RGB_G = rgb[led_sel][GRN];
-		PWM_RGB_B = rgb[led_sel][BLU];
+		PWM_RGB_R = (rgb[led_sel][RED] >> 1) + (rgb[led_sel][RED] >> 2);	//  75%
+		PWM_RGB_G = (rgb[led_sel][GRN] >> 2) + (rgb[led_sel][GRN] >> 3);	//  62%
+		PWM_RGB_B = (rgb[led_sel][BLU]     ) + (rgb[led_sel][BLU] << 2);	// 125%
 	} else {
 		// clear PWMs in piezo mode when piezo should be active
 		PWM_RGB_R = PWM_RGB_G = PWM_RGB_B = 0;
diff --git a/src/main.c b/src/main.c
index bf3968c..f753f7c 100644
--- a/src/main.c
+++ b/src/main.c
@@ -142,6 +142,13 @@ __attribute__ ((long_call, section(".ramfunc"))) void SysTick_Handler(void)
         // shifted counter for use in the program
         cs = ctr >> 2;
 
+        // run LED program (if in LED mode) at 256Hz
+        if (!(cs & 0x3)) {
+            if (userio_get_mode() == MODE_FUN) {
+                rgbprog_run();
+            }
+        }
+
 		// adc tested to result in about 61 reads/second
 		if (!adc_next()) {
 			// adc has new computed results
diff --git a/src/probe.c b/src/probe.c
index 02d375a..d7aba3e 100644
--- a/src/probe.c
+++ b/src/probe.c
@@ -35,7 +35,9 @@
 
 
 static uint16_t vref;
+
 static uint8_t latch = 0;
+static uint8_t buzzer = 0;
 
 
 
@@ -47,6 +49,11 @@ static inline void probe_measure_cont()
 	probe = adc_avg[ADC_PROBE];
 	v_ext = adc_avg[ADC_VREF_EXT];
 
+	// if the button has been pushed, toggle the buzzer
+	if (userio_get_btn() > 0) {
+		buzzer ^= 1;
+	}
+
 	// this LED will not set anything,
 	// but zero it out anyway
 	led_setrgb(1, 0, 0, 0);
@@ -61,13 +68,15 @@ static inline void probe_measure_cont()
 		}
 
 		if (latch) {
+			// indicate continuity
 			if (x >= 2420) latch--;	// hysteresis
 
-			led_setrgb(0, 0, 255, 0);
+			led_setrgb(0, 0, 200, ((buzzer) ? 500 : 0));
 			led_buzz(0);
-			if (knob[0] > 128) led_buzz(1);
+			if (buzzer) led_buzz(1);
 		} else {
-			led_setrgb(0, 64, 0, 0);
+			// idle
+			led_setrgb(0, 120, 0, ((buzzer) ?   8 : 0));
 			led_buzz(0);
 		}
 	}
@@ -86,22 +95,22 @@ static inline void probe_measure_diode()
 	led_setrgb(0, 0, 0, 0);
 
 	if (p < DIODE_SHORT) {
-		// off on short
+		// show off on short
 		led_setrgb(1, 0, 0, 0);
 	}
 
 	if (p >= DIODE_OPEN) {
-		// red on open
-		led_setrgb(1, 255, 0, 0);
+		// show red on open
+		led_setrgb(1, 120, 0, 0);
 	}
 
 	if (p >= 1940 && p < 2650) {
-		// green on regular or schottky diodes
-		led_setrgb(1, 0, 255, 0);
+		// show green on regular or schottky diodes
+		led_setrgb(1, 0, 200, 0);
 	}
 	if (p >= 2650 && p < 3800) {
-		// blue on LEDs
-		led_setrgb(1, 0, 0, 255);
+		// show blue on LEDs
+		led_setrgb(1, 0, 0, 500);
 	}
 
 	// if we haven't set a value, flash red to indicate error state
diff --git a/src/rgbprog.c b/src/rgbprog.c
index d6532fb..473d095 100644
--- a/src/rgbprog.c
+++ b/src/rgbprog.c
@@ -6,20 +6,96 @@
 
 
 #include "led.h"
+#include "hsv2rgb.h"
+#include "userio.h"
 
 
 
-void rgbprog_continuity()
+void rgbprog_rainbow();
+void rgbprog_rainbow_offset();
+
+static void (*proglist[8])(void) = {
+	rgbprog_rainbow,
+	rgbprog_rainbow_offset,
+};
+
+
+
+static uint8_t prog_active;
+static uint8_t prog_next;
+static uint8_t prog_cntr;
+
+static uint16_t brightness = 0;
+
+static color_hsv hsv[2];
+static color_rgb rgb[2];
+
+
+
+void rgbprog_run()
 {
+	uint32_t i;
+	uint8_t j;
 
-}
-
-void rgbprog_diode()
-{
-    
+	// if the button has been pushed, change the brightness
+	if (userio_get_btn() > 0) {
+		brightness++;
+		if (brightness > 2) brightness = 0;
+	}
+	
+	// which program to run?
+	j = 0;
+	for (i = 32; i <= 256; i += 32) {
+		if (knob[0] < i) {
+			if (proglist[j]) {
+				proglist[j]();
+			}
+			break;
+		}
+		j++;
+	}
 }
 
 void rgbprog_rainbow()
 {
+	int16_t w;
 
+	w  = knob[1];
+	w *= 2;
+	w  = 256 - w;
+
+	hsv[0].h += w;
+	if (hsv[0].h < 0) hsv[0].h += 0x3000;
+	hsv[0].h %= 0x3000;
+
+	hsv2rgb_8b(hsv[0].h >> 3, 255, 255, &rgb[0].r, &rgb[0].g, &rgb[0].b);
+	led_setrgb(0, rgb[0].r << brightness, rgb[0].g << brightness, rgb[0].b << brightness);
+	led_setrgb(1, rgb[0].r << brightness, rgb[0].g << brightness, rgb[0].b << brightness);
+}
+
+void rgbprog_rainbow_offset()
+{
+	rgbprog_rainbow();
+
+	hsv[1].h = hsv[0].h;
+	hsv[1].h += (knob[0] - 32) << 6;
+	hsv[1].h %= 0x3000;
+
+	hsv2rgb_8b(hsv[1].h >> 3, 255, 255, &rgb[0].r, &rgb[0].g, &rgb[0].b);
+	led_setrgb(1, rgb[0].r << brightness, rgb[0].g << brightness, rgb[0].b << brightness);
+}
+
+void rgbprog_randcolorfade()
+{
+
+}
+
+void rgbprog_randcolorfade_single()
+{
+
+}
+
+void rgbprog_randcolorfade_dual()
+{
+	
 }
\ No newline at end of file
diff --git a/src/userio.c b/src/userio.c
index 7d29bd2..d7a5e4a 100644
--- a/src/userio.c
+++ b/src/userio.c
@@ -131,6 +131,7 @@ void userio_parse()
 
 	// knobs
 	{
+		// SET0 is always connected, so just copy and scale it
 		knob[0] = adc_avg[ADC_SET0] >> 4;
 	
 		// SET1/VREFEXT input can be SET1 or VREFEXT, depending on PROBESEL.
@@ -143,7 +144,7 @@ void userio_parse()
 			} else {
 				x  = adc_avg[ADC_SET1] << 12;	// maximum possible level
 				x /= SET1_MAX;					// normalize to 4096max
-				knob[0] = (x >> 4) & 0xff;		// reduce to 8-bit
+				knob[1] = (x >> 4) & 0xff;		// reduce to 8-bit
 			}
 		}
 	}
@@ -152,4 +153,26 @@ void userio_parse()
 uint8_t userio_get_mode()
 {
 	return mode;
+}
+
+/*
+ * returns the button state.
+ * -1 = button is currently being pressed
+ *  0 = button is not being pressed
+ * >0 = button is not being pressed, but was (just?) released and held for X ticks
+ */
+int16_t userio_get_btn()
+{
+	int16_t ret;
+
+	if (btn) return -1;
+	if (!btn) {
+		if (btn_held) {
+			ret = btn_held;
+			btn_held = 0;
+			return ret;
+		}
+	}
+
+	return 0;
 }
\ No newline at end of file