Add larger photo for Gitea

LICENCE_ISC.md

@@ -0,0 +1,16 @@
+# ISC licence
+
+Copyright (c) 2020, fruchti<fruchti@gvfr.de>
+
+Permission to use, copy, modify, and/or distribute this software for any
+purpose with or without fee is hereby granted, provided that the above
+copyright notice and this permission notice appear in all copies.
+
+THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
+SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
+OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
+CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+

README.md

@@ -0,0 +1,9 @@
+# STM32F030F4P6 LED Tree
+
+![Photo](laurelin.jpg)
+
+This repository contains the code for a 8-by-6 RGB LED matrix driver with software 12-bit BCM output based on a STM32F030F4P6 and some additional code for brightness control and a pretty animation. More information about the project can be found [here](https://25120.org/post/laurelin/).
+
+## Licence
+
+The header files in the third_party directory are provided by ARM Limited and ST Microelectronics and contain their own licence information. Everything else is ISC licenced.

animation_lut.py

@@ -0,0 +1,20 @@
+#!/usr/bin/env python
+
+from colorsys import hsv_to_rgb
+
+LUT_SIZE = 256
+SATURATION = 0.8
+VALUE = 1
+RESOLUTION = 12     # in bits
+
+print('const LED_Colour_t Animation_ColourLUT[] =')
+print('{')
+for i in range(LUT_SIZE):
+    h = i / LUT_SIZE
+    rgb = hsv_to_rgb(h, SATURATION, VALUE)
+    # Gamma-correct
+    rgb = tuple(pow(x, 2.2) for x in rgb)
+    # Scale to BCM resolution
+    (r, g, b) = tuple(round(2 ** RESOLUTION * x) for x in rgb)
+    print('    {{ .r = {}, .g = {}, .b = {} }},'.format(r, g, b))
+print('};')

build-number.txt

@@ -1 +1 @@
-298
+515

ld/common_nvs.ld

@@ -12,6 +12,15 @@ SECTIONS
         _end_text = .;
     } >flash
 
+    /* Non-volatile storage area in flash */
+    .nvstore (NOLOAD) :
+    {
+        . = ALIGN(1K);
+        *(.nvstore*)
+        . = ALIGN(1K);
+        _end_nvstore = .;
+    } > flash_nvstore
+
     /* C++ initialiser code segments */
     .preinit_array :
     {

ld/stm32f030f4_15k_flash_1k_nvs.ld

@@ -1,7 +1,8 @@
 MEMORY
 {
-    flash (rx)                  : ORIGIN = 0x08000000, LENGTH = 16K
+    flash (rx)                  : ORIGIN = 0x08000000, LENGTH = 15K
+    flash_nvstore (rw)          : ORIGIN = 0x08003c00, LENGTH = 1K
     sram (xrw)                  : ORIGIN = 0x20000000, LENGTH = 4K
 }
 
-INCLUDE ld/common.ld
+INCLUDE ld/common_nvs.ld

makefile

@@ -10,7 +10,7 @@ DEBUG := yes
 H_DEVICE = STM32F030x6
 STARTUP_SOURCE_DIR = src
 STARTUP_SOURCES = $(STARTUP_SOURCE_DIR)/startup.S
-LD_SCRIPT = ld/stm32f030f4_flash.ld
+LD_SCRIPT = ld/stm32f030f4_15k_flash_1k_nvs.ld
 
 ifeq ($(DEBUG),yes)
 DEBUG_FLAGS = -DDEBUG -g3

src/animation.c

@@ -1,18 +1,107 @@
 #include "animation.h"
-#include "led.h"
+#include "animation_lut.h"
+#include "light_sensor.h"
+#include "nvs.h"
 
+volatile bool Animation_FrameFlag = false;
+
+#if LED_COLUMNS == 12
 const unsigned int Animation_LEDOrder[LED_COUNT] =
 {
-    // Red
+    19, 27, 21, 13, 0, 4, 24, 8, 12, 15, 6, 5, 28,
-     0,  1,  2,  3,  4,  5,
+    29, 17, 3, 18, 26, 22, 10, 16, 20, 30, 1,
-    // Green
+    25, 2, 14, 31, 7, 11, 9, 23
-     6,  7,  8,  9, 10, 11,
-    // Blue
-    12, 13, 14, 15, 16, 17,
-    // Yellow
-    18, 19, 20, 21, 22, 23,
-    // Cyan
-    24, 25, 26, 27, 28, 29,
-    // Fuchsia
-    30, 31
 };
+#elif LED_COLUMNS == 9
+const unsigned int Animation_LEDOrder[LED_COUNT] =
+{
+    19, 21, 13, 0, 4, 8, 12, 15, 6, 5,
+    17, 3, 18, 22, 10, 16, 20, 1,
+    2, 14, 7, 11, 9, 23
+};
+#endif
+
+LED_Colour_t Animation_GetColour(unsigned int step, unsigned int brightness)
+{
+    const unsigned int lut_size = sizeof(Animation_ColourLUT)
+        / sizeof(LED_Colour_t);
+
+    unsigned int index = step * lut_size / ANIMATION_STEPS;
+
+    LED_Colour_t colour = Animation_ColourLUT[index];
+
+    colour.r = ((unsigned int)colour.r * brightness) >> LIGHTSENSOR_BITS;
+    colour.g = ((unsigned int)colour.g * brightness) >> LIGHTSENSOR_BITS;
+    colour.b = ((unsigned int)colour.b * brightness) >> LIGHTSENSOR_BITS;
+
+    return colour;
+}
+
+void Animation_DrawGradient(unsigned int step_bottom, unsigned int step_top,
+    unsigned int brightness)
+{
+    if(step_bottom >= ANIMATION_STEPS)
+    {
+        step_bottom = 2 * ANIMATION_STEPS - step_bottom;
+    }
+    if(step_top >= ANIMATION_STEPS)
+    {
+        step_top = 2 * ANIMATION_STEPS - step_top;
+    }
+    for(int i = 0; i < LED_COUNT; i++)
+    {
+        unsigned int step = ((LED_COUNT - 1 - i) * step_bottom + i * step_top)
+            / (LED_COUNT - 1);
+        LED_PixelData[Animation_LEDOrder[i]] = Animation_GetColour(step,
+            brightness);
+    }
+}
+
+void Animation_Init(void)
+{
+    RCC->APB2ENR |= RCC_APB2ENR_TIM17EN;
+
+    TIM17->PSC = 8000 - 1;
+    TIM17->ARR = 1000 / ANIMATION_REFRESH_RATE;
+    TIM17->DIER = TIM_DIER_UIE;
+    TIM17->CR1 = TIM_CR1_CEN;
+    NVIC_EnableIRQ(TIM17_IRQn);
+}
+
+void Animation_Poll(void)
+{
+    if(!Animation_FrameFlag)
+    {
+        return;
+    }
+    Animation_FrameFlag = false;
+
+    NVS_Data->animation_step_bottom += ANIMATION_STEPS
+        / ANIMATION_CYCLE_TIME_BOTTOM
+        / ANIMATION_REFRESH_RATE;
+    NVS_Data->animation_step_top += ANIMATION_STEPS
+        / ANIMATION_CYCLE_TIME_TOP
+        / ANIMATION_REFRESH_RATE;
+
+    NVS_Data->animation_step_bottom %= 2 * ANIMATION_STEPS;
+    NVS_Data->animation_step_top %= 2 * ANIMATION_STEPS;
+
+    Animation_DrawGradient(NVS_Data->animation_step_bottom,
+            NVS_Data->animation_step_top,
+            LightSensor_RelativeBrightness);
+    LED_Commit();
+
+    static unsigned int store_counter = 0;
+    store_counter++;
+    if(store_counter >= ANIMATION_NVS_STORE_INTERVAL * ANIMATION_REFRESH_RATE)
+    {
+        store_counter = 0;
+        NVS_Save(false);
+    }
+}
+
+void TIM17_IRQHandler(void)
+{
+    Animation_FrameFlag = true;
+    TIM17->SR &= ~TIM_SR_UIF;
+}

src/animation.h

@@ -1 +1,25 @@
 #pragma once
+
+#include <stdbool.h>
+
+#include "led.h"
+
+#define ANIMATION_STEPS         (1 << 24)
+
+#define ANIMATION_REFRESH_RATE  10
+
+// Cycle time of the animation for the bottom end of the gradient (in seconds)
+#define ANIMATION_CYCLE_TIME_BOTTOM \
+                                (6 * 24 * 60 * 60)
+// Cycle time of the animation for the top end of the gradient (in seconds)
+#define ANIMATION_CYCLE_TIME_TOP \
+                                (8 * 24 * 60 * 60)
+
+// Interval for saving the current animation step to NVS (in seconds)
+#define ANIMATION_NVS_STORE_INTERVAL \
+                                (60 * 60)
+
+extern const unsigned int Animation_LEDOrder[LED_COUNT];
+
+void Animation_Init(void);
+void Animation_Poll(void);

src/animation_lut.c

@@ -0,0 +1,261 @@
+#include "animation_lut.h"
+
+const LED_Colour_t Animation_ColourLUT[] =
+{
+    { .r = 4096, .g = 119, .b = 119 },
+    { .r = 4096, .g = 145, .b = 119 },
+    { .r = 4096, .g = 173, .b = 119 },
+    { .r = 4096, .g = 205, .b = 119 },
+    { .r = 4096, .g = 239, .b = 119 },
+    { .r = 4096, .g = 277, .b = 119 },
+    { .r = 4096, .g = 317, .b = 119 },
+    { .r = 4096, .g = 360, .b = 119 },
+    { .r = 4096, .g = 407, .b = 119 },
+    { .r = 4096, .g = 456, .b = 119 },
+    { .r = 4096, .g = 509, .b = 119 },
+    { .r = 4096, .g = 565, .b = 119 },
+    { .r = 4096, .g = 623, .b = 119 },
+    { .r = 4096, .g = 686, .b = 119 },
+    { .r = 4096, .g = 751, .b = 119 },
+    { .r = 4096, .g = 820, .b = 119 },
+    { .r = 4096, .g = 891, .b = 119 },
+    { .r = 4096, .g = 967, .b = 119 },
+    { .r = 4096, .g = 1045, .b = 119 },
+    { .r = 4096, .g = 1127, .b = 119 },
+    { .r = 4096, .g = 1212, .b = 119 },
+    { .r = 4096, .g = 1301, .b = 119 },
+    { .r = 4096, .g = 1393, .b = 119 },
+    { .r = 4096, .g = 1489, .b = 119 },
+    { .r = 4096, .g = 1588, .b = 119 },
+    { .r = 4096, .g = 1690, .b = 119 },
+    { .r = 4096, .g = 1796, .b = 119 },
+    { .r = 4096, .g = 1906, .b = 119 },
+    { .r = 4096, .g = 2019, .b = 119 },
+    { .r = 4096, .g = 2135, .b = 119 },
+    { .r = 4096, .g = 2256, .b = 119 },
+    { .r = 4096, .g = 2380, .b = 119 },
+    { .r = 4096, .g = 2507, .b = 119 },
+    { .r = 4096, .g = 2638, .b = 119 },
+    { .r = 4096, .g = 2773, .b = 119 },
+    { .r = 4096, .g = 2911, .b = 119 },
+    { .r = 4096, .g = 3053, .b = 119 },
+    { .r = 4096, .g = 3199, .b = 119 },
+    { .r = 4096, .g = 3349, .b = 119 },
+    { .r = 4096, .g = 3502, .b = 119 },
+    { .r = 4096, .g = 3659, .b = 119 },
+    { .r = 4096, .g = 3820, .b = 119 },
+    { .r = 4096, .g = 3984, .b = 119 },
+    { .r = 4040, .g = 4096, .b = 119 },
+    { .r = 3874, .g = 4096, .b = 119 },
+    { .r = 3712, .g = 4096, .b = 119 },
+    { .r = 3554, .g = 4096, .b = 119 },
+    { .r = 3399, .g = 4096, .b = 119 },
+    { .r = 3249, .g = 4096, .b = 119 },
+    { .r = 3102, .g = 4096, .b = 119 },
+    { .r = 2958, .g = 4096, .b = 119 },
+    { .r = 2819, .g = 4096, .b = 119 },
+    { .r = 2683, .g = 4096, .b = 119 },
+    { .r = 2550, .g = 4096, .b = 119 },
+    { .r = 2422, .g = 4096, .b = 119 },
+    { .r = 2297, .g = 4096, .b = 119 },
+    { .r = 2175, .g = 4096, .b = 119 },
+    { .r = 2057, .g = 4096, .b = 119 },
+    { .r = 1943, .g = 4096, .b = 119 },
+    { .r = 1832, .g = 4096, .b = 119 },
+    { .r = 1725, .g = 4096, .b = 119 },
+    { .r = 1621, .g = 4096, .b = 119 },
+    { .r = 1521, .g = 4096, .b = 119 },
+    { .r = 1425, .g = 4096, .b = 119 },
+    { .r = 1331, .g = 4096, .b = 119 },
+    { .r = 1242, .g = 4096, .b = 119 },
+    { .r = 1155, .g = 4096, .b = 119 },
+    { .r = 1072, .g = 4096, .b = 119 },
+    { .r = 992, .g = 4096, .b = 119 },
+    { .r = 916, .g = 4096, .b = 119 },
+    { .r = 843, .g = 4096, .b = 119 },
+    { .r = 773, .g = 4096, .b = 119 },
+    { .r = 707, .g = 4096, .b = 119 },
+    { .r = 644, .g = 4096, .b = 119 },
+    { .r = 584, .g = 4096, .b = 119 },
+    { .r = 527, .g = 4096, .b = 119 },
+    { .r = 473, .g = 4096, .b = 119 },
+    { .r = 423, .g = 4096, .b = 119 },
+    { .r = 375, .g = 4096, .b = 119 },
+    { .r = 331, .g = 4096, .b = 119 },
+    { .r = 290, .g = 4096, .b = 119 },
+    { .r = 251, .g = 4096, .b = 119 },
+    { .r = 216, .g = 4096, .b = 119 },
+    { .r = 184, .g = 4096, .b = 119 },
+    { .r = 154, .g = 4096, .b = 119 },
+    { .r = 127, .g = 4096, .b = 119 },
+    { .r = 119, .g = 4096, .b = 136 },
+    { .r = 119, .g = 4096, .b = 163 },
+    { .r = 119, .g = 4096, .b = 194 },
+    { .r = 119, .g = 4096, .b = 227 },
+    { .r = 119, .g = 4096, .b = 264 },
+    { .r = 119, .g = 4096, .b = 303 },
+    { .r = 119, .g = 4096, .b = 346 },
+    { .r = 119, .g = 4096, .b = 391 },
+    { .r = 119, .g = 4096, .b = 439 },
+    { .r = 119, .g = 4096, .b = 491 },
+    { .r = 119, .g = 4096, .b = 546 },
+    { .r = 119, .g = 4096, .b = 603 },
+    { .r = 119, .g = 4096, .b = 665 },
+    { .r = 119, .g = 4096, .b = 729 },
+    { .r = 119, .g = 4096, .b = 796 },
+    { .r = 119, .g = 4096, .b = 867 },
+    { .r = 119, .g = 4096, .b = 941 },
+    { .r = 119, .g = 4096, .b = 1019 },
+    { .r = 119, .g = 4096, .b = 1099 },
+    { .r = 119, .g = 4096, .b = 1184 },
+    { .r = 119, .g = 4096, .b = 1271 },
+    { .r = 119, .g = 4096, .b = 1362 },
+    { .r = 119, .g = 4096, .b = 1456 },
+    { .r = 119, .g = 4096, .b = 1554 },
+    { .r = 119, .g = 4096, .b = 1656 },
+    { .r = 119, .g = 4096, .b = 1760 },
+    { .r = 119, .g = 4096, .b = 1869 },
+    { .r = 119, .g = 4096, .b = 1981 },
+    { .r = 119, .g = 4096, .b = 2096 },
+    { .r = 119, .g = 4096, .b = 2215 },
+    { .r = 119, .g = 4096, .b = 2338 },
+    { .r = 119, .g = 4096, .b = 2464 },
+    { .r = 119, .g = 4096, .b = 2594 },
+    { .r = 119, .g = 4096, .b = 2728 },
+    { .r = 119, .g = 4096, .b = 2865 },
+    { .r = 119, .g = 4096, .b = 3006 },
+    { .r = 119, .g = 4096, .b = 3150 },
+    { .r = 119, .g = 4096, .b = 3298 },
+    { .r = 119, .g = 4096, .b = 3450 },
+    { .r = 119, .g = 4096, .b = 3606 },
+    { .r = 119, .g = 4096, .b = 3766 },
+    { .r = 119, .g = 4096, .b = 3929 },
+    { .r = 119, .g = 4096, .b = 4096 },
+    { .r = 119, .g = 3929, .b = 4096 },
+    { .r = 119, .g = 3766, .b = 4096 },
+    { .r = 119, .g = 3606, .b = 4096 },
+    { .r = 119, .g = 3450, .b = 4096 },
+    { .r = 119, .g = 3298, .b = 4096 },
+    { .r = 119, .g = 3150, .b = 4096 },
+    { .r = 119, .g = 3006, .b = 4096 },
+    { .r = 119, .g = 2865, .b = 4096 },
+    { .r = 119, .g = 2728, .b = 4096 },
+    { .r = 119, .g = 2594, .b = 4096 },
+    { .r = 119, .g = 2464, .b = 4096 },
+    { .r = 119, .g = 2338, .b = 4096 },
+    { .r = 119, .g = 2215, .b = 4096 },
+    { .r = 119, .g = 2096, .b = 4096 },
+    { .r = 119, .g = 1981, .b = 4096 },
+    { .r = 119, .g = 1869, .b = 4096 },
+    { .r = 119, .g = 1760, .b = 4096 },
+    { .r = 119, .g = 1656, .b = 4096 },
+    { .r = 119, .g = 1554, .b = 4096 },
+    { .r = 119, .g = 1456, .b = 4096 },
+    { .r = 119, .g = 1362, .b = 4096 },
+    { .r = 119, .g = 1271, .b = 4096 },
+    { .r = 119, .g = 1184, .b = 4096 },
+    { .r = 119, .g = 1099, .b = 4096 },
+    { .r = 119, .g = 1019, .b = 4096 },
+    { .r = 119, .g = 941, .b = 4096 },
+    { .r = 119, .g = 867, .b = 4096 },
+    { .r = 119, .g = 796, .b = 4096 },
+    { .r = 119, .g = 729, .b = 4096 },
+    { .r = 119, .g = 665, .b = 4096 },
+    { .r = 119, .g = 603, .b = 4096 },
+    { .r = 119, .g = 546, .b = 4096 },
+    { .r = 119, .g = 491, .b = 4096 },
+    { .r = 119, .g = 439, .b = 4096 },
+    { .r = 119, .g = 391, .b = 4096 },
+    { .r = 119, .g = 346, .b = 4096 },
+    { .r = 119, .g = 303, .b = 4096 },
+    { .r = 119, .g = 264, .b = 4096 },
+    { .r = 119, .g = 227, .b = 4096 },
+    { .r = 119, .g = 194, .b = 4096 },
+    { .r = 119, .g = 163, .b = 4096 },
+    { .r = 119, .g = 136, .b = 4096 },
+    { .r = 127, .g = 119, .b = 4096 },
+    { .r = 154, .g = 119, .b = 4096 },
+    { .r = 184, .g = 119, .b = 4096 },
+    { .r = 216, .g = 119, .b = 4096 },
+    { .r = 251, .g = 119, .b = 4096 },
+    { .r = 290, .g = 119, .b = 4096 },
+    { .r = 331, .g = 119, .b = 4096 },
+    { .r = 375, .g = 119, .b = 4096 },
+    { .r = 423, .g = 119, .b = 4096 },
+    { .r = 473, .g = 119, .b = 4096 },
+    { .r = 527, .g = 119, .b = 4096 },
+    { .r = 584, .g = 119, .b = 4096 },
+    { .r = 644, .g = 119, .b = 4096 },
+    { .r = 707, .g = 119, .b = 4096 },
+    { .r = 773, .g = 119, .b = 4096 },
+    { .r = 843, .g = 119, .b = 4096 },
+    { .r = 916, .g = 119, .b = 4096 },
+    { .r = 992, .g = 119, .b = 4096 },
+    { .r = 1072, .g = 119, .b = 4096 },
+    { .r = 1155, .g = 119, .b = 4096 },
+    { .r = 1242, .g = 119, .b = 4096 },
+    { .r = 1331, .g = 119, .b = 4096 },
+    { .r = 1425, .g = 119, .b = 4096 },
+    { .r = 1521, .g = 119, .b = 4096 },
+    { .r = 1621, .g = 119, .b = 4096 },
+    { .r = 1725, .g = 119, .b = 4096 },
+    { .r = 1832, .g = 119, .b = 4096 },
+    { .r = 1943, .g = 119, .b = 4096 },
+    { .r = 2057, .g = 119, .b = 4096 },
+    { .r = 2175, .g = 119, .b = 4096 },
+    { .r = 2297, .g = 119, .b = 4096 },
+    { .r = 2422, .g = 119, .b = 4096 },
+    { .r = 2550, .g = 119, .b = 4096 },
+    { .r = 2683, .g = 119, .b = 4096 },
+    { .r = 2819, .g = 119, .b = 4096 },
+    { .r = 2958, .g = 119, .b = 4096 },
+    { .r = 3102, .g = 119, .b = 4096 },
+    { .r = 3249, .g = 119, .b = 4096 },
+    { .r = 3399, .g = 119, .b = 4096 },
+    { .r = 3554, .g = 119, .b = 4096 },
+    { .r = 3712, .g = 119, .b = 4096 },
+    { .r = 3874, .g = 119, .b = 4096 },
+    { .r = 4040, .g = 119, .b = 4096 },
+    { .r = 4096, .g = 119, .b = 3984 },
+    { .r = 4096, .g = 119, .b = 3820 },
+    { .r = 4096, .g = 119, .b = 3659 },
+    { .r = 4096, .g = 119, .b = 3502 },
+    { .r = 4096, .g = 119, .b = 3349 },
+    { .r = 4096, .g = 119, .b = 3199 },
+    { .r = 4096, .g = 119, .b = 3053 },
+    { .r = 4096, .g = 119, .b = 2911 },
+    { .r = 4096, .g = 119, .b = 2773 },
+    { .r = 4096, .g = 119, .b = 2638 },
+    { .r = 4096, .g = 119, .b = 2507 },
+    { .r = 4096, .g = 119, .b = 2380 },
+    { .r = 4096, .g = 119, .b = 2256 },
+    { .r = 4096, .g = 119, .b = 2135 },
+    { .r = 4096, .g = 119, .b = 2019 },
+    { .r = 4096, .g = 119, .b = 1906 },
+    { .r = 4096, .g = 119, .b = 1796 },
+    { .r = 4096, .g = 119, .b = 1690 },
+    { .r = 4096, .g = 119, .b = 1588 },
+    { .r = 4096, .g = 119, .b = 1489 },
+    { .r = 4096, .g = 119, .b = 1393 },
+    { .r = 4096, .g = 119, .b = 1301 },
+    { .r = 4096, .g = 119, .b = 1212 },
+    { .r = 4096, .g = 119, .b = 1127 },
+    { .r = 4096, .g = 119, .b = 1045 },
+    { .r = 4096, .g = 119, .b = 967 },
+    { .r = 4096, .g = 119, .b = 891 },
+    { .r = 4096, .g = 119, .b = 820 },
+    { .r = 4096, .g = 119, .b = 751 },
+    { .r = 4096, .g = 119, .b = 686 },
+    { .r = 4096, .g = 119, .b = 623 },
+    { .r = 4096, .g = 119, .b = 565 },
+    { .r = 4096, .g = 119, .b = 509 },
+    { .r = 4096, .g = 119, .b = 456 },
+    { .r = 4096, .g = 119, .b = 407 },
+    { .r = 4096, .g = 119, .b = 360 },
+    { .r = 4096, .g = 119, .b = 317 },
+    { .r = 4096, .g = 119, .b = 277 },
+    { .r = 4096, .g = 119, .b = 239 },
+    { .r = 4096, .g = 119, .b = 205 },
+    { .r = 4096, .g = 119, .b = 173 },
+    { .r = 4096, .g = 119, .b = 145 },
+};

src/animation_lut.h

@@ -0,0 +1,5 @@
+#pragma once
+
+#include "led.h"
+
+extern const LED_Colour_t Animation_ColourLUT[256];

src/led.c

@@ -3,7 +3,10 @@
 
 LED_Colour_t LED_PixelData[LED_COUNT] = {{0}};
 volatile bool LED_FrameFlag = false;
+volatile bool LED_SuspendFlag = false;
+bool LED_Suspended = false;
 
+#if LED_COLUMNS == 12
 #define LED_ODR_MASK            ((1 << PIN_LED_R_0) | (1 << PIN_LED_G_0) \
                                 | (1 << PIN_LED_B_0) | (1 << PIN_LED_R_1) \
                                 | (1 << PIN_LED_G_1) | (1 << PIN_LED_B_1) \
@@ -24,6 +27,27 @@ volatile bool LED_FrameFlag = false;
                                 | (1 << PIN_LED_R_2 * 2) | (1 << PIN_LED_G_2 * 2) \
                                 | (1 << PIN_LED_B_2 * 2) | (1 << PIN_LED_R_3 * 2) \
                                 | (1 << PIN_LED_G_3 * 2) | (1 << PIN_LED_B_3 * 2))
+#elif LED_COLUMNS == 9
+#define LED_ODR_MASK            ((1 << PIN_LED_R_0) | (1 << PIN_LED_G_0) \
+                                | (1 << PIN_LED_B_0) | (1 << PIN_LED_R_1) \
+                                | (1 << PIN_LED_G_1) | (1 << PIN_LED_B_1) \
+                                | (1 << PIN_LED_R_2) | (1 << PIN_LED_G_2) \
+                                | (1 << PIN_LED_B_2))
+
+#define LED_MODER_MASK          ((3 << PIN_LED_R_0 * 2) | (3 << PIN_LED_G_0 * 2) \
+                                | (3 << PIN_LED_B_0 * 2) | (3 << PIN_LED_R_1 * 2) \
+                                | (3 << PIN_LED_G_1 * 2) | (3 << PIN_LED_B_1 * 2) \
+                                | (3 << PIN_LED_R_2 * 2) | (3 << PIN_LED_G_2 * 2) \
+                                | (3 << PIN_LED_B_2 * 2))
+
+#define LED_MODER               ((1 << PIN_LED_R_0 * 2) | (1 << PIN_LED_G_0 * 2) \
+                                | (1 << PIN_LED_B_0 * 2) | (1 << PIN_LED_R_1 * 2) \
+                                | (1 << PIN_LED_G_1 * 2) | (1 << PIN_LED_B_1 * 2) \
+                                | (1 << PIN_LED_R_2 * 2) | (1 << PIN_LED_G_2 * 2) \
+                                | (1 << PIN_LED_B_2 * 2))
+#else
+#error Unsupported LED column count
+#endif
 
 // TIM3 is clocked by APB1 and thus receives only half the system clock. The 4
 // LSBs have bit lengths 2, 4, 8, and 16 cycles and are generated blocking from
@@ -33,6 +57,7 @@ static const uint16_t LED_BitLengths[LED_BITS - 4] =
     16, 32, 64, 128, 256, 512, 1024, 2048
 };
 
+#if LED_COLUMNS == 12
 static const int LED_Pins[LED_COLUMNS] =
 {
     PIN_LED_R_0, PIN_LED_G_0, PIN_LED_B_0,
@@ -40,6 +65,14 @@ static const int LED_Pins[LED_COLUMNS] =
     PIN_LED_R_2, PIN_LED_G_2, PIN_LED_B_2,
     PIN_LED_R_3, PIN_LED_G_3, PIN_LED_B_3
 };
+#elif LED_COLUMNS == 9
+static const int LED_Pins[LED_COLUMNS] =
+{
+    PIN_LED_R_0, PIN_LED_G_0, PIN_LED_B_0,
+    PIN_LED_R_1, PIN_LED_G_1, PIN_LED_B_1,
+    PIN_LED_R_2, PIN_LED_G_2, PIN_LED_B_2
+};
+#endif
 
 // Number of 16-bit values to be transferred to the GPIO's output register via
 // DMA. Each value contains output values for all columns. For each row, a
@@ -58,6 +91,11 @@ static volatile bool LED_QueuePageFlip = false;
 
 void LED_Commit(void)
 {
+    if(LED_Suspended)
+    {
+        return;
+    }
+
     // Wait for the current data to be displayed in case LED_Commit was called
     // more than one time during a single frame. Otherwise, a race condition
     // might occur.
@@ -67,15 +105,13 @@ void LED_Commit(void)
     {
         for(int i = 0; i < LED_COLUMNS; i++)
         {
-            // Use pixel data as a raw byte buffer to get R, G, B in order
+            // Use pixel data as a raw word buffer to get R, G, B in order
-            uint8_t colour_value = ((uint8_t*)LED_PixelData)[r * LED_COLUMNS + i];
+            uint16_t colour_value =
-            uint16_t gamma_corrected = (uint16_t)colour_value;
+                ((uint16_t*)LED_PixelData)[r * LED_COLUMNS + i];
-            gamma_corrected *= gamma_corrected;
-            gamma_corrected >>= 16 - LED_BITS;
 
             for(int j = 0; j < LED_BITS; j++)
             {
-                if(gamma_corrected & (1 << j))
+                if(colour_value & (1 << j))
                 {
                     LED_BackBuffer[r * (LED_BITS + 1) + j] &=
                         ~(1 << LED_Pins[i]);
@@ -108,7 +144,7 @@ static void LED_StartBCM(int row)
     TIM3->ARR = LED_BitLengths[0];
     TIM3->DIER = TIM_DIER_UDE | TIM_DIER_CC1DE;
 
-    // DMA channel 3: Output data to port a on TIM3 update
+    // DMA channel 3: output data to port a on TIM3 update event
     DMA1_Channel3->CMAR = (uint32_t)&(LED_FrontBuffer[row * (LED_BITS + 1) + 4]);
     // One transfer for each bit plus one to set the outputs to zero again.
     // The first 4 are sent out with assembly before the first DMA transfer.
@@ -117,7 +153,7 @@ static void LED_StartBCM(int row)
     DMA1_Channel3->CCR = DMA_CCR_PL | DMA_CCR_MSIZE_0 | DMA_CCR_PSIZE_0
         | DMA_CCR_MINC | DMA_CCR_DIR | DMA_CCR_EN | DMA_CCR_TCIE;
 
-    // DMA channel 3: Output data to port a on TIM3 update
+    // DMA channel 4: update TIM3 ARR on TIM3 compare 1 match
     // The bit lengths table is offset because the first value is already in
     // the timer's ARR shadow register.
     DMA1_Channel4->CMAR = (uint32_t)&(LED_BitLengths[1]);
@@ -215,6 +251,7 @@ void LED_Init(void)
     RCC->APB1ENR |= RCC_APB1ENR_TIM3EN;
 
     // Fill both DMA buffers
+    LED_QueuePageFlip = false;
     LED_Commit();
     LED_PageFlip();
     LED_Commit();
@@ -244,6 +281,53 @@ void LED_Init(void)
     LED_StartBCM(0);
 }
 
+void LED_Suspend(void)
+{
+    if(LED_Suspended)
+    {
+        return;
+    }
+
+    LED_SuspendFlag = true;
+    while(LED_SuspendFlag);
+
+    // Disable timer and DMA channels
+    TIM3->CR1 = 0x0000;
+    TIM3->DIER = 0x0000;
+    TIM3->CNT = 0;
+    DMA1->IFCR = DMA_IFCR_CTCIF3;
+    DMA1_Channel3->CCR = 0x0000;
+    DMA1_Channel4->CCR = 0x0000;
+    NVIC_DisableIRQ(DMA1_Channel2_3_IRQn);
+    NVIC_ClearPendingIRQ(DMA1_Channel2_3_IRQn);
+
+    // Deactivate all rows and columns
+    GPIOA->BSRR = LED_ODR_MASK;
+    GPIOF->BSRR = (1 << PIN_ROW_DATA);
+    for(int i = 0; i < LED_ROWS + 1; i++)
+    {
+        LED_PulseRowClock();
+    }
+
+    // Disable timer and DMA clocks
+    RCC->AHBENR &= ~RCC_AHBENR_DMA1EN;
+    RCC->APB1ENR &= ~RCC_APB1ENR_TIM3EN;
+
+    LED_Suspended = true;
+}
+
+void LED_WakeUp(void)
+{
+    if(!LED_Suspended)
+    {
+        return;
+    }
+
+    LED_Init();
+
+    LED_Suspended = false;
+}
+
 void DMA1_Channel2_3_IRQHandler(void)
 {
     // Interrupt when all bits have been sent
@@ -268,6 +352,12 @@ void DMA1_Channel2_3_IRQHandler(void)
         LED_PulseRowClock();
     }
 
+    if(LED_SuspendFlag)
+    {
+        LED_SuspendFlag = false;
+        return;
+    }
+
     // Start sending bits out again. The row offset caused by the shift
     // register "lagging" one clock cycle behind because RCK and SCK are
     // connected to the same signal doesn't matter here: we're not paying much

src/led.h

@@ -5,17 +5,19 @@
 #include "stm32f030x6.h"
 #include "pinning.h"
 
-#define LED_BITS                12
+#define LED_BITS                12  // BCM resolution in bits
 #define LED_ROWS                8   // Rows are driven by a shift register
-#define LED_COLUMNS             12  // Columns are driven by the MCU directly
+#define LED_COLUMNS             12  // Columns are driven by the MCU directly.
+                                    // Set to 9 to free the SWD pins and enable
+                                    // debugging.
 #define LED_COUNT               (LED_ROWS * LED_COLUMNS / 3)
 
 typedef struct
 {
-    uint8_t r;
+    uint16_t r;
-    uint8_t g;
+    uint16_t g;
-    uint8_t b;
+    uint16_t b;
-} __attribute__((packed)) LED_Colour_t;
+} __attribute__((packed, aligned(2))) LED_Colour_t;
 
 // Pixel data, not displayed until LED_Commit() is called
 extern LED_Colour_t LED_PixelData[LED_COUNT];
@@ -27,6 +29,11 @@ extern volatile bool LED_FrameFlag;
 void LED_InitShiftRegister(void);
 void LED_Init(void);
 
+// Enter power-saving mode (LEDs off)
+void LED_Suspend(void);
+
+// Leave power-saving mode
+void LED_WakeUp(void);
+
 // Display LED_PixelData, starting with the next frame
 void LED_Commit(void);
-

src/light_sensor.c

@@ -4,13 +4,9 @@ volatile unsigned int LightSensor_Measurement;
 volatile bool LightSensor_NewMeasurement = false;
 
 // Rolling average of the brightness measurement
-float LightSensor_AbsoluteBrightness = 0.5f;
+unsigned int LightSensor_AbsoluteBrightness = 0;
 
-// Maximum and minimum encountered so far
+int LightSensor_RelativeBrightness;
-float LightSensor_MinimumBrightness = 1.0f;
-float LightSensor_MaximumBrightness = 0.0f;
-
-float LightSensor_RelativeBrightness;
 
 static void LightSensor_Measure(void)
 {
@@ -66,35 +62,25 @@ void LightSensor_Poll(void)
     {
         unsigned int measurement = LightSensor_Measurement;
         LightSensor_NewMeasurement = false;
-        float brightness = 65535.0f / measurement;
+        unsigned int brightness = ((1 << 31)
-        LightSensor_AbsoluteBrightness = LIGHTSENSOR_LAMBDA * LightSensor_AbsoluteBrightness
+            / (measurement + 1)) >> (31 - 16);
-            + (1.0f - LIGHTSENSOR_LAMBDA) * brightness;
+        LightSensor_AbsoluteBrightness -= LightSensor_AbsoluteBrightness
+            >> LIGHTSENSOR_LAMBDA_BITS;
+        LightSensor_AbsoluteBrightness += brightness
+            >> LIGHTSENSOR_LAMBDA_BITS;
 
-        if(LightSensor_AbsoluteBrightness < LightSensor_MinimumBrightness)
+        LightSensor_RelativeBrightness =
-        {
+            ((int)LightSensor_AbsoluteBrightness - LIGHTSENSOR_LOW_BOUND)
-            LightSensor_MinimumBrightness = LightSensor_AbsoluteBrightness;
+            * LIGHTSENSOR_MAX
-        }
+            / (LIGHTSENSOR_HIGH_BOUND - LIGHTSENSOR_LOW_BOUND);
-        if(LightSensor_AbsoluteBrightness > LightSensor_MaximumBrightness)
-        {
-            LightSensor_MaximumBrightness = LightSensor_AbsoluteBrightness;
-        }
 
-        // Scale and saturate to get relative brightness value
+        if(LightSensor_RelativeBrightness < 0)
-        float range = LightSensor_MaximumBrightness
-            - LightSensor_MinimumBrightness;
-        float low = LightSensor_MinimumBrightness
-            + range * LIGHTSENSOR_LOW_BOUND;
-        float high = LightSensor_MinimumBrightness
-            + range * LIGHTSENSOR_HIGH_BOUND;
-        LightSensor_RelativeBrightness = (LightSensor_AbsoluteBrightness - low)
-            / (high - low);
-        if(LightSensor_RelativeBrightness < 0.0f)
         {
-            LightSensor_RelativeBrightness = 0.0f;
+            LightSensor_RelativeBrightness = 0;
         }
-        if(LightSensor_RelativeBrightness > 1.0f)
+        if(LightSensor_RelativeBrightness > LIGHTSENSOR_MAX)
         {
-            LightSensor_RelativeBrightness = 1.0f;
+            LightSensor_RelativeBrightness = LIGHTSENSOR_MAX;
         }
     }
 }

src/light_sensor.h

@@ -6,17 +6,21 @@
 #include "pinning.h"
 
 // ADC polling interval in milliseconds
-#define LIGHTSENSOR_INTERVAL    250
+#define LIGHTSENSOR_INTERVAL    500
+
+// Resolution of the brightness output
+#define LIGHTSENSOR_BITS        12
+#define LIGHTSENSOR_MAX         ((1 << LIGHTSENSOR_BITS) - 1)
 
 // 'Forgetting factor' of the rolling brightness average
-#define LIGHTSENSOR_LAMBDA      0.9f
+#define LIGHTSENSOR_LAMBDA_BITS 2
 
-// Bounds for converting absolute to relative brightness: Consider everything
+// Bounds for converting absolute to relative brightness (empirically
-// near the minimum or maximum 0.0 or 1.0, respectively
+// determined)
-#define LIGHTSENSOR_LOW_BOUND   0.005f
+#define LIGHTSENSOR_LOW_BOUND   5
-#define LIGHTSENSOR_HIGH_BOUND  0.9f
+#define LIGHTSENSOR_HIGH_BOUND  ((int)(0.85 * LIGHTSENSOR_MAX))
 
-extern float LightSensor_RelativeBrightness;
+extern int LightSensor_RelativeBrightness;
 
 void LightSensor_Init(void);
 void LightSensor_Poll(void);

src/main.c

@@ -5,74 +5,37 @@ int main(void)
     LED_InitShiftRegister();
     LightSensor_Init();
 
+    bool powered_down = false;
+
     // Delay a bit to make programming easier
     for(unsigned int i = 0; i < 1000; i++)
     {
         LightSensor_Poll();
     }
 
+    NVS_Load();
     LED_Init();
+    Animation_Init();
 
-    unsigned int counter = 0;
-    const unsigned int blink_period = 1000;
-    const unsigned int group_size = 6;
     while(1)
     {
         __WFI();
         LightSensor_Poll();
+        Animation_Poll();
 
-        if(LED_FrameFlag)
+        if(LightSensor_RelativeBrightness == 0 && !powered_down)
         {
-            memset(LED_PixelData, 0, sizeof(LED_PixelData));
+            LED_Suspend();
-
+            NVS_Save(true);
-            for(unsigned int i = 0; i < LED_COUNT; i++)
+            powered_down = true;
-            {
-                uint8_t brightness = 0;
-                if((counter / blink_period) <= (i % group_size))
-                {
-                    if(counter / (blink_period / 2) % 2)
-                    {
-                        brightness = 30;
         }
-                }
+        if(powered_down && LightSensor_RelativeBrightness > 0)
-
-                switch(i / group_size)
         {
-                    case 0:
+            powered_down = false;
-                        LED_PixelData[i].r = brightness;
+            NVS_Save(true);
-                        break;
+            LED_WakeUp();
-                    case 1:
-                        LED_PixelData[i].g = brightness;
-                        break;
-                    case 2:
-                        LED_PixelData[i].b = brightness;
-                        break;
-                    case 3:
-                        LED_PixelData[i].r = brightness;
-                        LED_PixelData[i].g = brightness;
-                        break;
-                    case 4:
-                        LED_PixelData[i].g = brightness;
-                        LED_PixelData[i].b = brightness;
-                        break;
-                    case 5:
-                        LED_PixelData[i].b = brightness;
-                        LED_PixelData[i].r = brightness;
-                        break;
-                }
-
-                counter++;
-                if(counter > blink_period * (group_size + 2))
-                {
-                    counter = 0;
-                }
-            }
-
-            LED_FrameFlag = false;
-            LED_Commit();
         }
     }
 
     return 0;
 }
-

src/main.h

@@ -1,11 +1,13 @@
 #pragma once
 
 #include <string.h>
+#include <stdbool.h>
 
 #include "stm32f030x6.h"
 #include "buildid.h"
 #include "led.h"
 #include "light_sensor.h"
+#include "animation.h"
+#include "nvs.h"
 
 int main(void);
-

src/nvs.c

@@ -0,0 +1,204 @@
+#include <stddef.h>
+#include <string.h>
+
+#include "nvs.h"
+
+// Note that the area used for storage must be aligned to the flash's pages. If
+// you want to use a larger area, be sure to also change the size and location
+// in the linker script.
+#define NVS_AREA_SIZE           1024
+#define NVS_BLOCK_COUNT         (NVS_AREA_SIZE / sizeof(NVS_Block_t))
+#define NVS_VALID_BLOCK_MARKER  0xab34
+
+typedef struct
+__attribute__((packed, aligned(2)))
+{
+    // Actual block data
+    NVS_Data_t data;
+
+    // Ensure struct size is divisible by two
+    uint8_t padding[sizeof(NVS_Data_t) % 2];
+
+    // Block marker for detecting if the block is the current or an old block
+    uint16_t marker;
+
+    uint32_t crc;
+} NVS_Block_t;
+
+__attribute__((used, section(".nvstore")))
+NVS_Block_t NVS_Area[NVS_BLOCK_COUNT];
+
+NVS_Block_t *NVS_FlashData;
+__attribute__((used))
+NVS_Block_t NVS_RAMData;
+
+NVS_Data_t *const NVS_Data = &NVS_RAMData.data;
+
+static uint32_t NVS_CalculateCRC(NVS_Data_t *data)
+{
+    CRC->CR = CRC_CR_RESET;
+    for(unsigned int i = 0; i < sizeof(NVS_Data_t); i++)
+    {
+        CRC->DR = ((uint8_t*)(data))[i];
+    }
+    return CRC->DR;
+}
+
+static bool NVS_ProgramHalfWord(uint16_t *dest, uint16_t value)
+{
+    FLASH->CR = FLASH_CR_PG;
+    *(uint16_t*)dest = value;
+    while(FLASH->SR & FLASH_SR_BSY);
+    if(*dest != value)
+    {
+        // Write failed
+        FLASH->CR = 0x00000000;
+        return false;
+    }
+    FLASH->CR = 0x00000000;
+    return true;
+}
+
+static void NVS_UnlockFlash(void)
+{
+    while(FLASH->SR & FLASH_SR_BSY);
+    if(FLASH->CR & FLASH_CR_LOCK)
+    {
+        FLASH->KEYR = 0x45670123;
+        FLASH->KEYR = 0xcdef89ab;
+    }
+}
+
+static bool NVS_EraseArea(void)
+{
+    for(unsigned int i = 0; i < NVS_AREA_SIZE; i += 1024)
+    {
+        while(FLASH->SR & FLASH_SR_BSY);
+        FLASH->CR = FLASH_CR_PER;
+        FLASH->AR = (uint32_t)NVS_Area + i;
+        FLASH->CR |= FLASH_CR_STRT;
+        while(FLASH->SR & FLASH_SR_BSY);
+        if(FLASH->SR & FLASH_SR_EOP)
+        {
+            // Clear EOP flag
+            FLASH->SR = FLASH_SR_EOP;
+        }
+        else
+        {
+            // Erase failed
+            FLASH->CR = 0x00000000;
+            return false;
+        }
+        FLASH->CR = 0x00000000;
+    }
+    return true;
+}
+
+static bool NVS_BlockEmpty(NVS_Block_t *block)
+{
+    for(unsigned int i = 0; i < sizeof(NVS_Block_t) / 2; i++)
+    {
+        if(*((uint16_t*)block + i) != 0xffff)
+        {
+            return false;
+        }
+    }
+    return true;
+}
+
+static void NVS_LoadDefaults(void)
+{
+    NVS_Data->animation_step_bottom = 0;
+    NVS_Data->animation_step_top = 0;
+}
+
+bool NVS_Load(void)
+{
+    RCC->AHBENR |= RCC_AHBENR_CRCEN;
+
+    NVS_Block_t *block = NULL;
+
+    // Find valid block
+    for(unsigned int i = 0; i < NVS_BLOCK_COUNT; i++)
+    {
+        block = &NVS_Area[i];
+        if(block->marker == NVS_VALID_BLOCK_MARKER)
+        {
+            // Valid block found, next up is the CRC check
+            break;
+        }
+        else if(block->marker == 0xffff)
+        {
+            // This block was erased and no block before was valid, so we can
+            // assume there is no valid block
+            block = NULL;
+            break;
+        }
+    }
+
+    if(block == NULL || block->marker != NVS_VALID_BLOCK_MARKER
+        || block->crc != NVS_CalculateCRC(&block->data))
+    {
+        // No valid block found
+        NVS_LoadDefaults();
+        return false;
+    }
+    else
+    {
+        // Valid block and CRC check successful
+        NVS_FlashData = block;
+        memcpy(&NVS_RAMData, (void*)block, sizeof(NVS_Block_t));
+        return true;
+    }
+}
+
+bool NVS_Save(bool erase_if_needed)
+{
+    NVS_UnlockFlash();
+
+    // Currently loaded block. Is NULL if the defaults were loaded in NVS_Load()
+    // instead of some flash contents.
+    NVS_Block_t *current_block = NVS_FlashData;
+    NVS_Block_t *next_block = NVS_FlashData + 1;
+
+    if(current_block == NULL || next_block > NVS_Area + NVS_BLOCK_COUNT
+        || !NVS_BlockEmpty(next_block))
+    {
+        if(!erase_if_needed)
+        {
+            return false;
+        }
+
+        if(!NVS_EraseArea())
+        {
+            return false;
+        }
+        next_block = &NVS_Area[0];
+        current_block = NULL;
+    }
+
+    NVS_RAMData.crc = NVS_CalculateCRC(NVS_Data);
+    NVS_RAMData.marker = NVS_VALID_BLOCK_MARKER;
+
+    // The block length is guaranteed to be divisible by 2
+    for(unsigned int i = 0; i < sizeof(NVS_Block_t) / 2; i++)
+    {
+        if(!NVS_ProgramHalfWord((uint16_t*)next_block + i,
+            *((uint16_t*)&NVS_RAMData + i)))
+        {
+            return false;
+        }
+    }
+
+    if(current_block != NULL)
+    {
+        if(!NVS_ProgramHalfWord((uint16_t*)&current_block->marker, 0x0000))
+        {
+            return false;
+        }
+    }
+
+    NVS_FlashData = next_block;
+
+    return true;
+}

src/nvs.h

@@ -0,0 +1,26 @@
+#pragma once
+
+#include <stdbool.h>
+
+#include "stm32f030x6.h"
+
+typedef struct
+__attribute__((packed, aligned(2)))
+{
+    unsigned int animation_step_bottom;
+    unsigned int animation_step_top;
+} NVS_Data_t;
+
+extern NVS_Data_t *const NVS_Data;
+
+// Returns true if the data was successfully loaded from flash and false if the
+// defaults were restored instead
+bool NVS_Load(void);
+
+// Stores the current contents of NVS_Data to flash. Pass false as a parameter
+// to skip saving unless it can be done without a flash page erase. Returns true
+// if the operation succeeds and false if there is was an error or erasing was
+// disallowed but would have been necessary.
+bool NVS_Save(bool erase_if_needed);
+
+

src/system.c

@@ -6,4 +6,3 @@ void SystemInit(void)
     // Disable all interrupts
     RCC->CIR = 0x00000000;
 }
-