aux-led: add a temperature mode in standby

Add a temperature mode which can be used to show current (ambient)
temperature during standby using the AUX led.

In this temperature mode, the preview (7H when iterating through
each mode) will blink AUX LED with the current temperature mapping
(and also button LED if there is button LED).

spaghetti-monster/anduril/aux-leds.c

@@ -71,6 +71,26 @@ uint8_t voltage_to_rgb() {
     return pgm_read_byte(rgb_led_colors + color_num);
 }
 
+uint8_t temperature_to_rgb() {
+    static const uint8_t temp_levels[] = {
+    // temperature in Celsius, color
+          0, 5, // 5, R + B =>pink/purple  <=12 C
+         12, 4, // 4,     B                (12,16] C
+         16, 3, // 3,   G+B =>cyan         (16,20] C
+         20, 2, // 2,   G                  (20,25] C
+         25, 1, // 1, R+G   =>yellow       (25,28] C
+         28, 0, // 0, R                    >28 C
+        255, 0, // 0, R
+    };
+    int16_t temps = temperature;
+    if (temps < 0) return 0;
+
+    uint8_t i;
+    for (i = 0; temps >= temp_levels[i]; i += 2) {}
+    uint8_t color_num = temp_levels[(i - 2) + 1];
+    return pgm_read_byte(rgb_led_colors + color_num);
+}
+
 // do fancy stuff with the RGB aux LEDs
 // mode: 0bPPPPCCCC where PPPP is the pattern and CCCC is the color
 // arg: time slice number
@@ -122,7 +142,7 @@ void rgb_led_update(uint8_t mode, uint8_t arg) {
         }
         actual_color = pgm_read_byte(colors + rainbow);
     }
-    else {  // voltage
+    else if (color == 9) {  // voltage
         // show actual voltage while asleep...
         if (go_to_standby) {
             actual_color = voltage_to_rgb();
@@ -136,6 +156,13 @@ void rgb_led_update(uint8_t mode, uint8_t arg) {
             actual_color = pgm_read_byte(colors + (((arg>>1) % 3) << 1));
         }
     }
+    else {   // temperature
+        actual_color = temperature_to_rgb();
+        if (!go_to_standby) {
+            // during preview, flash current temperature's colors quickly
+            pattern = (arg >> 1) % 3;
+        }
+    }
 
     // pick a brightness from the animation sequence
     if (pattern == 3) {

spaghetti-monster/anduril/aux-leds.h

@@ -52,8 +52,10 @@ void rgb_led_voltage_readout(uint8_t bright);
  * 4:   B
  * 5: R B
  * 6: RGB
- * 7: rainbow
- * 8: voltage
+ * 7: disco
+ * 8: rainbow
+ * 9: voltage
+ * 10: temperature
  */
 const PROGMEM uint8_t rgb_led_colors[] = {
     0b00000001,  // 0: red
@@ -64,8 +66,6 @@ const PROGMEM uint8_t rgb_led_colors[] = {
     0b00010001,  // 5: purple
     0b00010101,  // 6: white
 };
-// intentionally 1 higher than total modes, to make "voltage" easier to reach
-// (at Hank's request)
 #define RGB_LED_NUM_COLORS 11
 #define RGB_LED_NUM_PATTERNS 4
 #ifndef RGB_LED_OFF_DEFAULT