feat: prove build, flashing, and stable basic operation

src/main.c

@@ -1 +1,141 @@
-void app_main() {}
+#include <inttypes.h>
+#include <stddef.h>
+#include <stdint.h>
+
+#include "driver/gpio.h"
+#include "esp_chip_info.h"
+#include "esp_err.h"
+#include "esp_flash.h"
+#include "esp_log.h"
+#include "esp_system.h"
+#include "esp_timer.h"
+#include "freertos/FreeRTOS.h"
+#include "freertos/task.h"
+
+static const char *const kLogTag = "bringup";
+static const gpio_num_t kCandidateLedGpio = GPIO_NUM_8;
+static const uint32_t kLedProbeCount = 10;
+static const uint32_t kLedProbeIntervalMs = 500;
+static const uint32_t kHealthIntervalMs = 30000;
+static const uint32_t kStartupAttachmentDelayMs = 10000;
+
+static const char *reset_reason_name(esp_reset_reason_t reason) {
+  switch (reason) {
+    case ESP_RST_UNKNOWN:
+      return "unknown";
+    case ESP_RST_POWERON:
+      return "power_on";
+    case ESP_RST_EXT:
+      return "external";
+    case ESP_RST_SW:
+      return "software";
+    case ESP_RST_PANIC:
+      return "panic";
+    case ESP_RST_INT_WDT:
+      return "interrupt_watchdog";
+    case ESP_RST_TASK_WDT:
+      return "task_watchdog";
+    case ESP_RST_WDT:
+      return "other_watchdog";
+    case ESP_RST_DEEPSLEEP:
+      return "deep_sleep";
+    case ESP_RST_BROWNOUT:
+      return "brownout";
+    case ESP_RST_SDIO:
+      return "sdio";
+    case ESP_RST_USB:
+      return "usb";
+    case ESP_RST_JTAG:
+      return "jtag";
+    case ESP_RST_EFUSE:
+      return "efuse";
+    case ESP_RST_PWR_GLITCH:
+      return "power_glitch";
+    case ESP_RST_CPU_LOCKUP:
+      return "cpu_lockup";
+  }
+
+  return "unrecognized";
+}
+
+static void log_heap(uint64_t uptime_ms) {
+  const size_t free_heap_bytes = esp_get_free_heap_size();
+  const size_t minimum_free_heap_bytes = esp_get_minimum_free_heap_size();
+  uint32_t flash_size_bytes = 0;
+  const esp_err_t flash_result = esp_flash_get_size(NULL, &flash_size_bytes);
+
+  if (flash_result == ESP_OK) {
+    ESP_LOGI(kLogTag,
+             "health uptime_ms=%" PRIu64 " reset_reason=%s flash_bytes=%" PRIu32
+             " free_heap_bytes=%u min_free_heap_bytes=%u",
+             uptime_ms,
+             reset_reason_name(esp_reset_reason()),
+             flash_size_bytes,
+             (unsigned int)free_heap_bytes,
+             (unsigned int)minimum_free_heap_bytes);
+  } else {
+    ESP_LOGE(kLogTag, "health flash_size_failed=%s", esp_err_to_name(flash_result));
+  }
+}
+
+static void probe_candidate_led(void) {
+  ESP_LOGI(kLogTag,
+           "led_probe gpio=%d transitions=%" PRIu32 " interval_ms=%" PRIu32 "; visually confirm the LED",
+           (int)kCandidateLedGpio,
+           kLedProbeCount,
+           kLedProbeIntervalMs);
+
+  esp_err_t result = gpio_reset_pin(kCandidateLedGpio);
+  if (result != ESP_OK) {
+    ESP_LOGW(kLogTag, "led_probe gpio_reset_pin failed: %s", esp_err_to_name(result));
+    return;
+  }
+
+  result = gpio_set_direction(kCandidateLedGpio, GPIO_MODE_OUTPUT);
+  if (result != ESP_OK) {
+    ESP_LOGW(kLogTag, "led_probe gpio_set_direction failed: %s", esp_err_to_name(result));
+    return;
+  }
+
+  for (uint32_t transition = 0; transition < kLedProbeCount; ++transition) {
+    gpio_set_level(kCandidateLedGpio, transition % 2U);
+    vTaskDelay(pdMS_TO_TICKS(kLedProbeIntervalMs));
+  }
+
+  gpio_set_level(kCandidateLedGpio, 0);
+  ESP_LOGI(kLogTag, "led_probe complete; USB serial remained available during probe");
+}
+
+static void log_startup(void) {
+  esp_chip_info_t chip_info = {0};
+  uint32_t flash_size_bytes = 0;
+  const esp_err_t flash_result = esp_flash_get_size(NULL, &flash_size_bytes);
+
+  esp_chip_info(&chip_info);
+  ESP_LOGI(kLogTag,
+           "startup reset_reason=%s chip_model=%d chip_revision=%d cores=%d features=0x%08" PRIx32,
+           reset_reason_name(esp_reset_reason()),
+           (int)chip_info.model,
+           chip_info.revision,
+           chip_info.cores,
+           chip_info.features);
+
+  if (flash_result == ESP_OK) {
+    ESP_LOGI(kLogTag, "startup flash_bytes=%" PRIu32, flash_size_bytes);
+  } else {
+    ESP_LOGE(kLogTag, "startup flash_size_failed=%s", esp_err_to_name(flash_result));
+  }
+
+  log_heap(0);
+}
+
+void app_main(void) {
+  vTaskDelay(pdMS_TO_TICKS(kStartupAttachmentDelayMs));
+  log_startup();
+  probe_candidate_led();
+
+  while (true) {
+    log_heap((uint64_t)(esp_timer_get_time() / 1000));
+    vTaskDelay(pdMS_TO_TICKS(kHealthIntervalMs));
+  }
+}