From 6edccc845d06f6863423cebc18172678ca4de312 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?King=20K=C3=A9vin?= <kingkevin@cuvoodoo.info>
Date: Sat, 26 Mar 2016 14:58:21 +0100
Subject: [PATCH] improve: set only LED if changed

---
 main.c | 22 ++++++++++++++--------
 1 file changed, 14 insertions(+), 8 deletions(-)

diff --git a/main.c b/main.c
index bb68c57..4966efa 100644
--- a/main.c
+++ b/main.c
@@ -206,23 +206,29 @@ static void clock_show_time(uint32_t time)
 	uint8_t brightness_second = (255*(time%ticks_second))/ticks_second; // get brightness for seconds
 	// set second LED
 	clock_leds[led_second*3+0] = brightness_second;
-	//clock_leds[led_second*3+1] = 0;
-	//clock_leds[led_second*3+2] = 0;
+	//clock_leds[led_second*3+1] = 0; // clear other colors (minutes/hours indication)
+	//clock_leds[led_second*3+2] = 0; // clear other colors (minutes/hours indication)
 	// set previous LED
 	led_second = (led_second==0) ? WS2812B_LEDS-1 : led_second-1; // previous LED
 	clock_leds[led_second*3+0] = 0xff-brightness_second;
-	//clock_leds[led_second*3+1] = 0;
-	//clock_leds[led_second*3+2] = 0;
+	//clock_leds[led_second*3+1] = 0; // clear other colors (minutes/hours indication)
+	//clock_leds[led_second*3+2] = 0; // clear other colors (minutes/hours indication)
 }
 
 /** @brief set the LEDs
  *  @details set the LED colors on WS2812b LEDs
  *  @note WS2812b LED color values need to be transmitted separately
  */
-static void leds_set(void)
+static void clock_leds_set(void)
 {
+	static uint8_t clock_leds_old[WS2812B_LEDS*3] = {0}; // backup so to only set when value changed
 	for (uint16_t i=0; i<LENGTH(clock_leds)/3; i++) {
-		ws2812b_set_rgb(i,clock_leds[i*3+0],clock_leds[i*3+1],clock_leds[i*3+2]);
+		if (clock_leds[i*3+0]!=clock_leds_old[i*3+0] || clock_leds[i*3+1]!=clock_leds_old[i*3+1] || clock_leds[i*3+2]!=clock_leds_old[i*3+2]) { // only set when value changed (since this costs time)
+			clock_leds_old[i*3+0] = clock_leds[i*3+0]; // memorise change
+			clock_leds_old[i*3+1] = clock_leds[i*3+1]; // memorise change
+			clock_leds_old[i*3+2] = clock_leds[i*3+2]; // memorise change
+			ws2812b_set_rgb(i,clock_leds[i*3+0],clock_leds[i*3+1],clock_leds[i*3+2]); // set new value (this costs time)
+		}
 	}
 }
 
@@ -232,7 +238,7 @@ static void leds_set(void)
 static void clock_set_time(uint32_t time)
 {
 	clock_show_time(time); // set time
-	leds_set(); // set the colors of all LEDs
+	clock_leds_set(); // set the colors of all LEDs
 	ws2812b_transmit(); // transmit set color
 }
 
@@ -294,7 +300,7 @@ int main(void)
 	ws2812b_setup(); // setup WS2812b LEDs
 	clock_hours(); // show hour markers
 	clock_clear(); // clear all LEDs
-	leds_set(); // set the colors of all LEDs
+	clock_leds_set(); // set the colors of all LEDs
 	ws2812b_transmit(); // transmit set color
 
 	// setup RTC module