add pico_multi_booter code

Code/pico_multi_booter/sd_boot/key_event.h

@@ -0,0 +1,21 @@
+#ifndef KEY_EVENT_H
+#define KEY_EVENT_H
+
+#include "i2ckbd.h"
+#include <stdio.h>
+#include <string.h>
+#include <pico/stdio.h>
+
+typedef enum {
+    KEY_ARROW_UP = 0xB5,
+    KEY_ARROW_LEFT = 0xB4,
+    KEY_ARROW_RIGHT = 0xB7,
+    KEY_ARROW_DOWN = 0xB6,
+    KEY_BACKSPACE = 0x08,
+    KEY_ENTER = 0x0A,
+} lv_key_t;
+
+void keypad_init(void);
+int keypad_get_key(void);
+
+#endif // KEY_EVENT_H