From 251ea5b5f689908265e45a0c45d8796f28ecd0fe Mon Sep 17 00:00:00 2001
From: Dennis Gnad <dennis@xorn.org>
Date: Mon, 14 Jan 2013 15:55:03 +0100
Subject: [PATCH] scale led colors to temperature in led_set

---
 firmware/cup.c | 24 ++++++++++++++++--------
 1 file changed, 16 insertions(+), 8 deletions(-)

diff --git a/firmware/cup.c b/firmware/cup.c
index 108ccf3..a2560a2 100644
--- a/firmware/cup.c
+++ b/firmware/cup.c
@@ -12,6 +12,9 @@
 
 #define TIMEOUT 255
 
+const uint16_t LED_GREEN_TEMP = 300;
+const uint16_t LED_RED_TEMP = 1200;
+
 const uint16_t TARGET_TEMP_MAX = 1520;
 
 uint8_t led_color = 0;
@@ -20,7 +23,6 @@ uint8_t setting_timeout = 0;
 
 uint8_t adc_pos = 0;
 uint16_t adc_sum = 0;
-uint16_t temperature_adc = 0;
 uint16_t target = 0;
 
 uint16_t temperature = 0;
@@ -71,13 +73,13 @@ ISR(PCINT0_vect)
 	input_state = new_state;
 }
 
-uint8_t control_output(uint16_t current_temp, uint16_t target_temp)
+uint8_t control_output()
 {
-	if (current_temp > target_temp)
+	if (temperature > target)
 	{
 		return 0;
 	} else {
-		return (uint8_t)((uint16_t)((uint32_t)((uint32_t)255*target_temp)/current_temp)/TARGET_TEMP_MAX);
+		return (uint8_t)((uint16_t)((uint32_t)((uint32_t)255*target)/temperature)/TARGET_TEMP_MAX);
 	}
 }
 
@@ -142,7 +144,14 @@ void led_init(void)
 
 void led_set(uint16_t value)
 {
-	OCR0A = OCR0B = led_color = value >> 8;
+	if (LED_GREEN_TEMP < value && value < LED_RED_TEMP) {
+		value = (value-LED_GREEN_TEMP) * 255/(LED_RED_TEMP-LED_GREEN_TEMP);
+	} else if (value < LED_GREEN_TEMP) {
+		value = 0;
+	} else {
+		value = 255;
+	}
+	OCR0A = OCR0B = (uint8_t)value;
 }
 
 void led_off(void)
@@ -192,11 +201,10 @@ int main(void)
 			adc_sum += ADC;
 			if(++adc_pos == 64)
 			{
-				temperature_adc = adc_sum;
+				temperature = linearize_temp(adc_sum);
 				adc_sum = 0;
 				adc_pos = 0;
-				temperature = linearize_temp(temperature_adc);
-				heat_output = control_output(temperature, target);
+				heat_output = control_output();
 			}
 		}