diff --git a/firmware/src/CMakeLists.txt b/firmware/src/CMakeLists.txt
index 952270f..658997c 100644
--- a/firmware/src/CMakeLists.txt
+++ b/firmware/src/CMakeLists.txt
@@ -4,7 +4,7 @@ set(LWIP_ROOT ${PICO_SDK_PATH}/lib/lwip)
 function(make_firmware board board_def)
     pico_sdk_init()
     add_executable(${board}
-        main.c slider.c rgb.c button.c save.c config.c commands.c
+        main.c slider.c rgb.c button.c savedata.c config.c commands.c
         cli.c mpr121.c hebtn.c lzfx.c usb_descriptors.c ps4_feat.c)
     target_compile_definitions(${board} PUBLIC ${board_def})
     pico_enable_stdio_usb(${board} 1)
diff --git a/firmware/src/cli.c b/firmware/src/cli.c
index 6725bc4..f5c5d33 100644
--- a/firmware/src/cli.c
+++ b/firmware/src/cli.c
@@ -7,8 +7,9 @@
 #include "pico/stdio.h"
 #include "pico/stdlib.h"
 #include "pico/bootrom.h"
+#include "pico/unique_id.h"
+
 #include "cli.h"
-#include "save.h"
 
 #define MAX_COMMANDS 32
 #define MAX_PARAMETERS 10
@@ -24,6 +25,13 @@ static int max_cmd_len = 0;
 
 static int num_commands = 0;
 
+uint64_t board_id_64()
+{
+    pico_unique_board_id_t id;
+    pico_get_unique_board_id(&id);
+    return *(uint64_t *)(id.id);
+}
+
 void cli_register(const char *cmd, cmd_handler_t handler, const char *help)
 {
     if (num_commands < MAX_COMMANDS) {
diff --git a/firmware/src/commands.c b/firmware/src/commands.c
index a0da068..245790e 100644
--- a/firmware/src/commands.c
+++ b/firmware/src/commands.c
@@ -10,7 +10,7 @@
 #include "config.h"
 #include "slider.h"
 #include "hebtn.h"
-#include "save.h"
+#include "savedata.h"
 #include "cli.h"
 
 #include "usb_descriptors.h"
@@ -190,7 +190,7 @@ static void handle_keymap(int argc, char *argv[])
     diva_cfg->hid.joy_map = match;
 
     disp_hid();
-    save_request(true);
+    savedata_request(true);
 
     printf("Please replug the controller to apply the change.\n");
 }
@@ -405,7 +405,7 @@ static void handle_debug(int argc, char *argv[])
 
 static void handle_save()
 {
-    save_request(true);
+    savedata_request(true);
 }
 
 static void handle_factory_reset()
diff --git a/firmware/src/config.c b/firmware/src/config.c
index bcc8c4b..99f232b 100644
--- a/firmware/src/config.c
+++ b/firmware/src/config.c
@@ -7,7 +7,7 @@
  */
 
 #include "config.h"
-#include "save.h"
+#include "savedata.h"
 
 diva_cfg_t *diva_cfg;
 
@@ -66,16 +66,16 @@ static void config_loaded()
 
 void config_changed()
 {
-    save_request(false);
+    savedata_request(false);
 }
 
 void config_factory_reset()
 {
     *diva_cfg = default_cfg;
-    save_request(true);
+    savedata_request(true);
 }
 
 void config_init()
 {
-    diva_cfg = (diva_cfg_t *)save_alloc(sizeof(*diva_cfg), &default_cfg, config_loaded);
+    diva_cfg = (diva_cfg_t *)savedata_alloc(sizeof(*diva_cfg), &default_cfg, config_loaded);
 }
diff --git a/firmware/src/main.c b/firmware/src/main.c
index 5cb3517..e010e12 100644
--- a/firmware/src/main.c
+++ b/firmware/src/main.c
@@ -24,7 +24,7 @@
 
 #include "board_defs.h"
 
-#include "save.h"
+#include "savedata.h"
 #include "config.h"
 #include "cli.h"
 #include "commands.h"
@@ -196,15 +196,18 @@ static void run_lights()
     }
 }
 
-static mutex_t core1_io_lock;
+static void core1_init()
+{
+    flash_safe_execute_core_init();
+}
+
 static void core1_loop()
 {
+    core1_init();
+
     while (1) {
-        if (mutex_try_enter(&core1_io_lock, NULL)) {
-            run_lights();
-            rgb_update();
-            mutex_exit(&core1_io_lock);
-        }
+        run_lights();
+        rgb_update();
         cli_fps_count(1);
         sleep_us(700);
     }
@@ -219,7 +222,7 @@ static void core0_loop()
 
         cli_run();
     
-        save_loop();
+        savedata_loop();
         cli_fps_count(0);
 
         button_update();
@@ -291,8 +294,7 @@ void init()
     update_check();
 
     config_init();
-    mutex_init(&core1_io_lock);
-    save_init(0xca44cafe, &core1_io_lock);
+    savedata_init(0xca44cafe);
 
     slider_init();
     rgb_init();
diff --git a/firmware/src/save.h b/firmware/src/save.h
deleted file mode 100644
index cde4229..0000000
--- a/firmware/src/save.h
+++ /dev/null
@@ -1,27 +0,0 @@
-/*
- * Controller Flash Save and Load
- * WHowe <github.com/whowechina>
- */
-
-#ifndef SAVE_H
-#define SAVE_H
-
-#include <stdlib.h>
-#include <stdint.h>
-#include <stdbool.h>
-
-#include "pico/multicore.h"
-
-uint32_t board_id_32();
-uint64_t board_id_64();
-
-/* It's safer to lock other I/O ops during saving, so we need a locker */
-typedef void (*io_locker_func)(bool pause);
-void save_init(uint32_t magic, mutex_t *lock);
-
-void save_loop();
-
-void *save_alloc(size_t size, void *def, void (*after_load)());
-void save_request(bool immediately);
-
-#endif
diff --git a/firmware/src/save.c b/firmware/src/savedata.c
similarity index 61%
rename from firmware/src/save.c
rename to firmware/src/savedata.c
index 3afec3c..10444a3 100644
--- a/firmware/src/save.c
+++ b/firmware/src/savedata.c
@@ -5,21 +5,20 @@
  * Config is stored in last sector of flash
  */
 
-#include "save.h"
+#include "savedata.h"
 
 #include <stdint.h>
 #include <stdlib.h>
+#include <stdio.h>
 #include <stdbool.h>
 #include <memory.h>
 
 
-#include "bsp/board.h"
 #include "pico/bootrom.h"
 #include "pico/stdio.h"
 
 #include "hardware/flash.h"
 #include "pico/multicore.h"
-#include "pico/unique_id.h"
 
 static struct {
     size_t size;
@@ -33,6 +32,9 @@ static uint32_t my_magic = 0xcafecafe;
 #define SAVE_TIMEOUT_US 5000000
 
 #define SAVE_SECTOR_OFFSET (PICO_FLASH_SIZE_BYTES - FLASH_SECTOR_SIZE)
+#define GLOBAL_SECTOR_NUM 2
+#define GLOBAL_SECTOR_SIZE (GLOBAL_SECTOR_NUM * FLASH_SECTOR_SIZE)
+#define GLOBAL_SECTOR_OFFSET (SAVE_SECTOR_OFFSET - GLOBAL_SECTOR_SIZE)
 
 typedef struct __attribute ((packed)) {
     uint32_t magic;
@@ -47,26 +49,25 @@ static int data_page = -1;
 static bool requesting_save = false;
 static uint64_t requesting_time = 0;
 
-static mutex_t *io_lock;
 
-static void save_program()
+static void do_write(void *param)
 {
-    old_data = new_data;
-
-    data_page = (data_page + 1) % (FLASH_SECTOR_SIZE / FLASH_PAGE_SIZE);
-    printf("\nProgram Flash %d %8lx\n", data_page, old_data.magic);
-    if (mutex_enter_timeout_us(io_lock, 100000)) {
-        sleep_ms(10); /* wait for all io operations to finish */
-        uint32_t ints = save_and_disable_interrupts();
         if (data_page == 0) {
             flash_range_erase(SAVE_SECTOR_OFFSET, FLASH_SECTOR_SIZE);
         }
         flash_range_program(SAVE_SECTOR_OFFSET + data_page * FLASH_PAGE_SIZE,
                             (uint8_t *)&old_data, FLASH_PAGE_SIZE);
-        restore_interrupts(ints);
-        mutex_exit(io_lock);
+}
+
+static void save_program()
+{
+    old_data = new_data;
+    data_page = (data_page + 1) % (FLASH_SECTOR_SIZE / FLASH_PAGE_SIZE);
+    printf("\nProgram Save %d %8lx ", data_page, old_data.magic);
+    if (flash_safe_execute(do_write, NULL, 1000) != PICO_OK) {
+        printf("Failed!\n");
     } else {
-        printf("Program Flash Failed.\n");
+        printf("Done.\n");
     }
 }
 
@@ -94,7 +95,7 @@ static void save_load()
 
     if (data_page < 0) {
         load_default();
-        save_request(false);
+        savedata_request(false);
         return;
     }
 
@@ -110,37 +111,15 @@ static void save_loaded()
     }
 }
 
-static union __attribute__((packed)) {
-    pico_unique_board_id_t id;
-    struct {
-        uint32_t id32h;
-        uint32_t id32l;
-    };
-    uint64_t id64;
-} board_id;
-
-uint32_t board_id_32()
-{
-    pico_get_unique_board_id(&board_id.id);
-    return board_id.id32h ^ board_id.id32l;
-}
-
-uint64_t board_id_64()
-{
-    pico_get_unique_board_id(&board_id.id);
-    return board_id.id64;
-}
-
-void save_init(uint32_t magic, mutex_t *locker)
+void savedata_init(uint32_t magic)
 {
     my_magic = magic;
-    io_lock = locker;
     save_load();
-    save_loop();
+    savedata_loop();
     save_loaded();
 }
 
-void save_loop()
+void savedata_loop()
 {
     if (requesting_save && (time_us_64() - requesting_time > SAVE_TIMEOUT_US)) {
         requesting_save = false;
@@ -152,10 +131,16 @@ void save_loop()
     }
 }
 
-void *save_alloc(size_t size, void *def, void (*after_load)())
+void *savedata_alloc(size_t size, void *def, void (*after_load)())
 {
+    size_t offset = 0;
+    if (module_num > 0) {
+        offset = modules[module_num - 1].offset + modules[module_num - 1].size;
+    }
+    if (offset + size > sizeof(default_data.data)) {
+        return NULL;
+    }
     modules[module_num].size = size;
-    size_t offset = module_num > 0 ? modules[module_num - 1].offset + size : 0;
     modules[module_num].offset = offset;
     modules[module_num].after_load = after_load;
     module_num++;
@@ -163,7 +148,7 @@ void *save_alloc(size_t size, void *def, void (*after_load)())
     return new_data.data + offset;
 }
 
-void save_request(bool immediately)
+void savedata_request(bool immediately)
 {
     if (!requesting_save) {
         printf("Save requested.\n");
@@ -173,6 +158,42 @@ void save_request(bool immediately)
     }
     if (immediately) {
         requesting_time = 0;
-        save_loop();
+        savedata_loop();
+    }
+}
+
+
+void savedata_read_global(size_t offset, void *data, size_t size)
+{
+    if ((data == NULL) || (size == 0) || (offset >= GLOBAL_SECTOR_SIZE)) {
+        return;
+    }
+    if (size > GLOBAL_SECTOR_SIZE - offset) {
+        size = GLOBAL_SECTOR_SIZE - offset;
+    }
+    memcpy(data, (void *)(XIP_BASE + GLOBAL_SECTOR_OFFSET + offset), size);
+}
+
+static void do_write_global(void *param)
+{
+    uintptr_t *p = (uintptr_t *)param;
+    const uint8_t *data = (const uint8_t *)p[0];
+    size_t size = (size_t)p[1];
+
+    flash_range_erase(GLOBAL_SECTOR_OFFSET, GLOBAL_SECTOR_NUM * FLASH_SECTOR_SIZE);
+    flash_range_program(GLOBAL_SECTOR_OFFSET, data, size);
+}
+
+void savedata_write_global(const void *data, size_t size)
+{
+    static uintptr_t param[2];
+    param[0] = (uintptr_t)data;
+    param[1] = size;
+
+    printf("Program Global %8x ", GLOBAL_SECTOR_OFFSET);
+    if (flash_safe_execute(do_write_global, param, 1000) != PICO_OK) {
+        printf("Failed!\n");
+    } else {
+        printf("Done.\n");
     }
 }
diff --git a/firmware/src/savedata.h b/firmware/src/savedata.h
new file mode 100644
index 0000000..d8078fb
--- /dev/null
+++ b/firmware/src/savedata.h
@@ -0,0 +1,26 @@
+/*
+ * Controller Flash Save and Load
+ * WHowe <github.com/whowechina>
+ */
+
+#ifndef SAVEDATA_H
+#define SAVEDATA_H
+
+#include <stdlib.h>
+#include <stdint.h>
+#include <stdbool.h>
+
+#include "pico/multicore.h"
+
+/* It's safer to lock other I/O ops during saving, so we need a locker */
+void savedata_init(uint32_t magic);
+
+void savedata_loop();
+
+void *savedata_alloc(size_t size, void *def, void (*after_load)());
+void savedata_request(bool immediately);
+
+void savedata_read_global(size_t offset, void *data, size_t size);
+void savedata_write_global(const void *data, size_t size);
+
+#endif