add fb mode test example

examples/fb_mode_test/CMakeLists.txt

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+cmake_minimum_required(VERSION 3.10.0)
+set(EXTRA_COMPONENT_DIRS "../../")
+include($ENV{IDF_PATH}/tools/cmake/project.cmake)
+project(firmware)

examples/fb_mode_test/main/CMakeLists.txt

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+set(app_sources "main.c")
+
+set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
+idf_component_register(SRCS ${app_sources} REQUIRES epdiy)

examples/fb_mode_test/main/main.c

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+/*
+ * Visual tests for framebuffer modes that are not commonly used by the high-level API.
+ * Currently, includes 2 pixel per byte (ppB) with static origin color and 8ppB with static origin
+ * color.
+ */
+
+#include <esp_heap_caps.h>
+#include <esp_log.h>
+#include <esp_sleep.h>
+#include <esp_timer.h>
+#include <esp_types.h>
+#include <freertos/FreeRTOS.h>
+#include <freertos/task.h>
+#include <inttypes.h>
+#include <stdio.h>
+#include <string.h>
+
+#include <epdiy.h>
+
+#include "sdkconfig.h"
+
+#define WAVEFORM EPD_BUILTIN_WAVEFORM
+
+// choose the default demo board depending on the architecture
+#ifdef CONFIG_IDF_TARGET_ESP32
+#define DEMO_BOARD epd_board_v6
+#elif defined(CONFIG_IDF_TARGET_ESP32S3)
+#define DEMO_BOARD epd_board_v7
+#endif
+
+// Singular framebuffer to use for all of the tests.
+// Allocated for 2ppB, the least compact that we test here.
+uint8_t* framebuffer;
+int fb_size;
+
+static inline void checkError(enum EpdDrawError err) {
+    if (err != EPD_DRAW_SUCCESS) {
+        ESP_LOGE("demo", "draw error: %X", err);
+    }
+}
+
+/**
+ * Clears the screen to white and resets the framebuffer.
+ */
+void clear() {
+    epd_poweron();
+    epd_clear();
+    epd_poweroff();
+    memset(framebuffer, 0xFF, fb_size);
+}
+
+void test_8ppB() {
+    clear();
+
+    // bytes in a line in 8ppB mode
+    int line_bytes = epd_width() / 8;
+
+    int start_line = 100;
+    int start_column = 80 / 8;
+
+    // draw differently aligned triangles to check for uniformity
+    for (int align = 0; align < 16; align++) {
+        for (int height = 0; height < 16; height++) {
+            for (int len = 0; len < height; len++) {
+                int line = (start_line + 16 * align + height);
+                int column = align + len;
+                uint8_t* line_address = framebuffer + (line_bytes * line);
+                *(line_address + start_column + column / 8) &= ~(1 << (column % 8));
+            }
+        }
+    }
+
+    int black_start_column = 160 / 8;
+
+    // draw a black area for later
+    for (int line = 0; line < 200; line++) {
+        uint8_t* line_address = framebuffer + (line_bytes * (start_line + line));
+        memset(line_address + black_start_column, 0, 32);
+    }
+
+    epd_poweron();
+    checkError(epd_draw_base(
+        epd_full_screen(),
+        framebuffer,
+        epd_full_screen(),
+        MODE_PACKING_8PPB | MODE_DU | PREVIOUSLY_WHITE,
+        25,
+        NULL,
+        NULL,
+        &epdiy_ED047TC2
+    ));
+    epd_poweroff();
+}
+
+void app_main() {
+    epd_init(&DEMO_BOARD, &ED060XC3, EPD_OPTIONS_DEFAULT);
+    // Set VCOM for boards that allow to set this in software (in mV).
+    // This will print an error if unsupported. In this case,
+    // set VCOM using the hardware potentiometer and delete this line.
+    epd_set_vcom(2100);
+
+    fb_size = epd_width() * epd_height() / 2;
+    framebuffer = heap_caps_aligned_alloc(16, fb_size, MALLOC_CAP_SPIRAM);
+
+    test_8ppB();
+
+    printf("going to sleep...\n");
+    epd_deinit();
+    esp_deep_sleep_start();
+}