设置可高度的Relase版本，不然Usb没法枚举，Debug速度太慢

ESP32/my_usb_project/rust_app/src/lib.rs

@@ -14,12 +14,62 @@ fn panic(_info: &core::panic::PanicInfo) -> ! {
     }
 }
 
+// HID 键码常量
+const HID_KEY_A: u8 = 0x04;
+const REPORT_ID_KEYBOARD: u8 = 1;
+const PD_MS_TO_TICKS: u32 = 1;
+
+// FFI 函数声明
+extern "C" {
+    fn rust_is_usb_mounted() -> bool;
+    fn rust_send_keyboard_report(report_id: u8, modifier: u8, keycode: *const u8);
+    fn rust_vTaskDelay(xTicksToDelay: u32);
+}
+
 #[no_mangle]
 extern "C" fn rust_app_main() {
     // 初始化代码
+    send_a_key();
     return;
 }
 
 #[export_name = "rust_usb_callback"]
 pub unsafe extern "C" fn usb_callback(_event: u32) {
+}
+
+/// 发送 A 键的按键事件
+fn send_a_key() {
+    // 等待 USB 设备挂载
+    let mut mounted = false;
+    for _ in 0..10 {
+        mounted = unsafe {
+            rust_is_usb_mounted()
+        };
+        if mounted {
+            break;
+        }
+        // 等待 100ms
+        unsafe {
+            rust_vTaskDelay(100 * PD_MS_TO_TICKS);
+        }
+    }
+
+    if mounted {
+        // 发送 A 键按下事件
+        let keycode = [HID_KEY_A, 0, 0, 0, 0, 0];
+        unsafe {
+            rust_send_keyboard_report(REPORT_ID_KEYBOARD, 0, keycode.as_ptr());
+        }
+
+        // 等待 50ms
+        unsafe {
+            rust_vTaskDelay(50 * PD_MS_TO_TICKS);
+        }
+
+        // 发送 A 键释放事件
+        let keycode = [0, 0, 0, 0, 0, 0];
+        unsafe {
+            rust_send_keyboard_report(REPORT_ID_KEYBOARD, 0, keycode.as_ptr());
+        }
+    }
 }