From c3b4806e85e567d00b85ec847edfc11cc991d4f6 Mon Sep 17 00:00:00 2001
From: merlokk <807634+merlokk@users.noreply.github.com>
Date: Mon, 21 Jan 2019 17:09:51 +0200
Subject: [PATCH] add led emission normalization

---
 targets/stm32l432/src/app.h    |  4 ++--
 targets/stm32l432/src/device.c |  7 ++++++-
 targets/stm32l432/src/led.c    | 31 +++++++++++++++++++++++++------
 3 files changed, 33 insertions(+), 9 deletions(-)

diff --git a/targets/stm32l432/src/app.h b/targets/stm32l432/src/app.h
index c14a7ed..1da200d 100644
--- a/targets/stm32l432/src/app.h
+++ b/targets/stm32l432/src/app.h
@@ -53,10 +53,10 @@ void hw_init(void);
 //                              0xRRGGBB
 #define LED_INIT_VALUE			0x000800
 #define LED_WINK_VALUE			0x000010
-#define LED_MAX_SCALER          30
+#define LED_MAX_SCALER          15
 #define LED_MIN_SCALER          1
 // # of ms between each change in LED
-#define HEARTBEAT_PERIOD        100
+#define HEARTBEAT_PERIOD        150
 // Each LED channel will be multiplied by a integer between LED_MAX_SCALER
 // and LED_MIN_SCALER to cause the slow pulse.  E.g.
 // #define LED_INIT_VALUE			0x301000
diff --git a/targets/stm32l432/src/device.c b/targets/stm32l432/src/device.c
index 7bc5f48..6187ff6 100644
--- a/targets/stm32l432/src/device.c
+++ b/targets/stm32l432/src/device.c
@@ -209,9 +209,14 @@ void heartbeat()
         val++;
     }
 
-    if (val > LED_MAX_SCALER || val < LED_MIN_SCALER)
+    if (val >= LED_MAX_SCALER || val <= LED_MIN_SCALER)
     {
         state = !state;
+
+		if (val > LED_MAX_SCALER)
+			val = LED_MAX_SCALER;
+		if (val < LED_MIN_SCALER)
+			val = LED_MIN_SCALER;
     }
 
 #ifdef LED_WINK_VALUE
diff --git a/targets/stm32l432/src/led.c b/targets/stm32l432/src/led.c
index 0bae6d8..ce9b7a0 100644
--- a/targets/stm32l432/src/led.c
+++ b/targets/stm32l432/src/led.c
@@ -29,20 +29,39 @@
 #include "device.h"
 #include "log.h"
 
+// normalization formula: 16.06*x^0.33 = (0%-100%)
+// here values: value * 10
+uint8_t norm_k[] = {
+	0,   80,  101, 115, 127, 137, 145, 153, 159, 166, 
+	172, 177, 182, 187, 192, 196, 200, 205, 208, 212, 
+	216, 219, 223, 226, 229, 232, 235, 238, 241, 245};
+#define norm_k_len sizeof(norm_k)
+
+uint32_t led_normalization(uint8_t value)
+{
+	if (value > norm_k_len - 1)
+	{
+		return value * 10;
+	} else {
+		return norm_k[value];
+	}
+}
+
 void led_rgb(uint32_t hex)
 {
-    uint32_t r = hex >> 16;
-    uint32_t g = (hex >> 8)&0xff;
-    uint32_t b = hex & 0xff;
+    uint32_t r = led_normalization((hex >> 16) & 0xff);
+    uint32_t g = led_normalization((hex >> 8) & 0xff);
+    uint32_t b = led_normalization(hex & 0xff);
 
     // CCR2 == blue
     // CCR3 == red
     // CCR4 == green
 
     // map and scale colors
-    TIM2->CCR2 = 1000 - (b * 1000)/(256);
-    TIM2->CCR3 = 1000 - (r * 1000)/(256*6);
-    TIM2->CCR4 = 1000 - (g * 1000)/(256);
+	// normalization table values: value * 10
+    TIM2->CCR2 = 1000 - (b * 100)/(256);
+    TIM2->CCR3 = 1000 - (r * 100)/(256*6);
+    TIM2->CCR4 = 1000 - (g * 100)/(256);
 }
 
 void led_test_colors()