Added WS2812 driver and examples (squashed commits)

examples/ws2812_rainbow/Makefile

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+# Makefile for the ws2812 Rainbow example
+
+PROGRAM=ws2812_rainbow
+EXTRA_COMPONENTS = extras/ws2812
+
+include ../../common.mk

examples/ws2812_rainbow/ws2812_rainbow.c

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+/**
+ * @file   es2812_rainbow.c
+ * @author Ondřej Hruška, 2016
+ *
+ * @brief  Example of a rainbow effect with
+ *         WS2812 connected to GPIO2.
+ *
+ * This demo is in the public domain.
+ */
+
+#include "espressif/esp_common.h"
+#include "FreeRTOS.h"
+#include "task.h"
+#include "esp/uart.h" // uart_set_baud
+#include <stdio.h> // printf
+#include <stdint.h>
+
+#include "ws2812.h"
+
+
+#define delay_ms(ms) vTaskDelay((ms) / portTICK_RATE_MS)
+
+
+/** GPIO number used to control the RGBs */
+static const uint8_t pin = 2;
+
+
+/**
+ * @brief "rainbow" animation with a single RGB led.
+ */
+void demo_single(void)
+{
+    // duration between color changes
+    const uint8_t delay = 25;
+
+    ws2812_rgb_t x = {.num = 0xFF0000}; // RED color
+
+    while (1) {
+        // iterate through the spectrum
+
+        // note: This would be _WAY_ easier with HSL
+
+        while(x.c.g < 0xFF) { x.c.g++; ws2812_set(pin, x.num); delay_ms(delay); } // R->RG
+        while(x.c.r > 0x00) { x.c.r--; ws2812_set(pin, x.num); delay_ms(delay); } // RG->G
+        while(x.c.b < 0xFF) { x.c.b++; ws2812_set(pin, x.num); delay_ms(delay); } // G->GB
+        while(x.c.g > 0x00) { x.c.g--; ws2812_set(pin, x.num); delay_ms(delay); } // GB->B
+        while(x.c.r < 0xFF) { x.c.r++; ws2812_set(pin, x.num); delay_ms(delay); } // B->BR
+        while(x.c.b > 0x00) { x.c.b--; ws2812_set(pin, x.num); delay_ms(delay); } // BR->R
+    }
+}
+
+
+/**
+ * @brief "rainbow" effect on a RGB strip (30 pixels - can be adjusted)
+ *
+ * This example shows how to use the "procedural generation" of colors.
+ *
+ * The pixel colors are calculated on the fly, which saves RAM
+ * (especially with large displays).
+ */
+void demo_strip(void *pvParameters)
+{
+    const uint8_t anim_step = 10;
+    const uint8_t anim_max = 250;
+
+    // Number of your "pixels"
+    const uint8_t pixel_count = 30;
+
+    // duration between color changes
+    const uint8_t delay = 25;
+
+    ws2812_rgb_t color = WS2812_RGB(anim_max, 0, 0);
+    uint8_t step = 0;
+
+    ws2812_rgb_t color2 = WS2812_RGB(anim_max, 0, 0);
+    uint8_t step2 = 0;
+
+    while (1) {
+
+        color = color2;
+        step = step2;
+
+        // Start a data sequence (disables interrupts)
+        ws2812_seq_start();
+
+        for (uint8_t i = 0; i < pixel_count; i++) {
+
+            // send a color
+            ws2812_seq_rgb(pin, color.num);
+
+            // now we have a few hundred nanoseconds
+            // to calculate the next color
+
+            if (i == 1) {
+                color2 = color;
+                step2 = step;
+            }
+
+            switch (step) {
+                case 0: color.c.g += anim_step; if (color.c.g >= anim_max) step++;  break;
+                case 1: color.c.r -= anim_step; if (color.c.r == 0) step++; break;
+                case 2: color.c.b += anim_step; if (color.c.b >= anim_max) step++; break;
+                case 3: color.c.g -= anim_step; if (color.c.g == 0) step++; break;
+                case 4: color.c.r += anim_step; if (color.c.r >= anim_max) step++; break;
+                case 5: color.c.b -= anim_step; if (color.c.b == 0) step = 0; break;
+            }
+        }
+
+        // End the data sequence, display colors (interrupts are restored)
+        ws2812_seq_end();
+
+        // wait a bit
+        delay_ms(delay);
+    }
+}
+
+
+
+
+void user_init(void)
+{
+    uart_set_baud(0, 115200);
+    printf("--- RGB Rainbow demo ---");
+
+    // Configure the GPIO
+    gpio_enable(pin, GPIO_OUTPUT);
+
+    // Select a demo function:
+
+#if true
+# define demo demo_strip
+#else
+# define demo demo_single
+#endif
+
+
+    // Choose how to run it:
+
+#if true
+
+    // Blocking function - works OK, because WiFi isn't
+    // initialized yet & we're hogging the CPU.
+
+    printf("Starting a blocking function.\r\n");
+    demo(NULL);
+
+#else
+
+    // Start a task. This is a real-life example,
+    // notice the glitches due to NMI.
+
+    printf("Starting a task. There may be glitches!\r\n");
+    xTaskCreate(&demo, (signed char *)"strip demo", 256, NULL, 10, NULL);
+#endif
+}