diff --git a/Readme.md b/Readme.md
index 1ab89d1..d35cfd3 100644
--- a/Readme.md
+++ b/Readme.md
@@ -71,13 +71,13 @@ Also be careful to prevent the motor from overheating.
 Then write 1 to `state` to enter the drag mode, where a constant current is continuously passed through some of the motor's coils
 (please complete the subsequent operations as soon as possible to prevent the motor from overheating).
 
-Write 1 to `cali_run` to start the calibration, the motor coil will be energized sequentially, the motor will turn clockwise first, then counterclockwise,
-and finally print the calculated encoder offset value, write it to `bias_encoder`, and finally save it. 
+Write 1 to `cali_run` to start the calibration. The motor coils will be energized sequentially, causing the motor to turn clockwise first, then counterclockwise.
+Afterward, the calculated encoder offset value will be printed and written to `bias_encoder`. Be sure to save it to flash.
 
-Write 1 to `cali_run` as soon as possible after writing 1 to `state`, so that the coils can be energized in turn, sharing the strain on individual coils. 
+Write 1 to `cali_run` as soon as possible after writing 1 to `state`, so that the coils can be energized in turn, sharing the strain on individual coils.
 
 If the motor does not rotate clockwise first during calibration (the encoder value not increases),
-you will need to swap any two wires of the motor to change the direction of motor rotation. 
+you will need to swap any two wires of the motor to change the direction of motor rotation.
 
 
 ### Torque Mode (state = 2)
diff --git a/mdrv_bl/Makefile b/mdrv_bl/Makefile
index a62fc3e..30a1503 100644
--- a/mdrv_bl/Makefile
+++ b/mdrv_bl/Makefile
@@ -62,8 +62,7 @@ Drivers/STM32G4xx_HAL_Driver/Src/stm32g4xx_hal_uart_ex.c \
 Core/Src/system_stm32g4xx.c \
 Core/Src/sysmem.c \
 Core/Src/syscalls.c \
-cdnet/dispatch/cdnet_dispatch.c \
-cdnet/dispatch/helper.c \
+cdnet/core/cdnet_core.c \
 cdnet/parser/cdnet_l0.c \
 cdnet/parser/cdnet_l1.c \
 cdnet/dev/cdctl.c \
@@ -138,7 +137,7 @@ C_INCLUDES =  \
 -IDrivers/CMSIS/Device/ST/STM32G4xx/Include \
 -IDrivers/CMSIS/Include \
 -Icdnet/parser \
--Icdnet/dispatch \
+-Icdnet/core \
 -Icdnet/utils \
 -Icdnet/dev \
 -Icdnet/arch/stm32 \
diff --git a/mdrv_bl/cdnet b/mdrv_bl/cdnet
index 170eb1f..eaad950 160000
--- a/mdrv_bl/cdnet
+++ b/mdrv_bl/cdnet
@@ -1 +1 @@
-Subproject commit 170eb1f081ac546a249090e2521f66bbdddbfc94
+Subproject commit eaad9501596f9305c7b51c5201a5cc1b832f6240
diff --git a/mdrv_bl/usr/app_main.h b/mdrv_bl/usr/app_main.h
index fa9c13f..56fc6e4 100644
--- a/mdrv_bl/usr/app_main.h
+++ b/mdrv_bl/usr/app_main.h
@@ -10,7 +10,7 @@
 #ifndef __APP_MAIN_H__
 #define __APP_MAIN_H__
 
-#include "cdnet_dispatch.h"
+#include "cdnet_core.h"
 #include "cd_debug.h"
 #include "cdbus_uart.h"
 #include "cdctl.h"
diff --git a/mdrv_fw/Makefile b/mdrv_fw/Makefile
index 3f8ed08..412056c 100644
--- a/mdrv_fw/Makefile
+++ b/mdrv_fw/Makefile
@@ -67,8 +67,7 @@ Drivers/STM32G4xx_HAL_Driver/Src/stm32g4xx_hal_uart_ex.c \
 Core/Src/system_stm32g4xx.c \
 Core/Src/sysmem.c \
 Core/Src/syscalls.c \
-cdnet/dispatch/cdnet_dispatch.c \
-cdnet/dispatch/helper.c \
+cdnet/core/cdnet_core.c \
 cdnet/parser/cdnet_l0.c \
 cdnet/parser/cdnet_l1.c \
 cdnet/dev/cdctl_it.c \
@@ -147,7 +146,7 @@ C_INCLUDES =  \
 -IDrivers/CMSIS/Device/ST/STM32G4xx/Include \
 -IDrivers/CMSIS/Include \
 -Icdnet/parser \
--Icdnet/dispatch \
+-Icdnet/core \
 -Icdnet/utils \
 -Icdnet/dev \
 -Icdnet/arch/stm32 \
diff --git a/mdrv_fw/cdnet b/mdrv_fw/cdnet
index 170eb1f..eaad950 160000
--- a/mdrv_fw/cdnet
+++ b/mdrv_fw/cdnet
@@ -1 +1 @@
-Subproject commit 170eb1f081ac546a249090e2521f66bbdddbfc94
+Subproject commit eaad9501596f9305c7b51c5201a5cc1b832f6240
diff --git a/mdrv_fw/usr/app_main.c b/mdrv_fw/usr/app_main.c
index 74c693d..8a64e6f 100644
--- a/mdrv_fw/usr/app_main.c
+++ b/mdrv_fw/usr/app_main.c
@@ -77,33 +77,6 @@ static void device_init(void)
 }
 
 
-extern uint32_t end; // end of bss
-#define STACK_CHECK_SKIP 0x200
-#define STACK_CHECK_SIZE (64 + STACK_CHECK_SKIP)
-
-static void stack_check_init(void)
-{
-    int i;
-    printf("stack_check_init: skip: %p ~ %p, to %p\n",
-            &end, &end + STACK_CHECK_SKIP, &end + STACK_CHECK_SIZE);
-    for (i = STACK_CHECK_SKIP; i < STACK_CHECK_SIZE; i+=4)
-        *(uint32_t *)(&end + i) = 0xababcdcd;
-}
-
-static void stack_check(void)
-{
-    int i;
-    for (i = STACK_CHECK_SKIP; i < STACK_CHECK_SIZE; i+=4) {
-        if (*(uint32_t *)(&end + i) != 0xababcdcd) {
-            printf("stack overflow %p (skip: %p ~ %p): %08lx\n",
-                    &end + i, &end, &end + STACK_CHECK_SKIP, *(uint32_t *)(&end + i));
-            d_error("stack overflow %p (skip: %p ~ %p): %08lx\n",
-                    &end + i, &end, &end + STACK_CHECK_SKIP, *(uint32_t *)(&end + i));
-            while (true);
-        }
-    }
-}
-
 #if 0
 static void dump_hw_status(void)
 {
@@ -317,7 +290,8 @@ void cali_elec_angle(void)
             d_info("cali: finished, result:\n");
             d_info("cali:  cw: %02x\n", (amount_f / csa.motor_poles) & 0xffff);
             d_info("cali: ccw: %02x\n", (amount_r / csa.motor_poles) & 0xffff);
-            d_info("cali: avg: %02x\n", ((amount_f + amount_r) / csa.motor_poles / 2) & 0xffff);
+            csa.bias_encoder = ((amount_f + amount_r) / csa.motor_poles / 2) & 0xffff;
+            d_info("cali: avg: %02x, updated to bias_encoder\n", csa.bias_encoder);
             uint8_t dat = ST_STOP;
             state_w_hook_before(0, 1, &dat);
             csa.state = ST_STOP;
@@ -354,11 +328,13 @@ void cali_elec_angle(void)
 
 void app_main(void)
 {
+    uint64_t *stack_check = (uint64_t *)((uint32_t)&end + 256);
+
     gpio_set_value(&led_r, 1);
     gpio_set_value(&led_g, 1);
     printf("\nstart app_main (mdrv)...\n");
+    *stack_check = 0xababcdcd12123434;
 
-    stack_check_init();
     load_conf();
     debug_init(&dft_ns, &csa.dbg_dst, &csa.dbg_en);
     device_init();
@@ -452,13 +428,17 @@ void app_main(void)
             }
         }
 
-        stack_check();
         app_motor_routine();
         cdn_routine(&dft_ns); // handle cdnet
         common_service_routine();
         cali_elec_angle();
         //dump_hw_status();
         debug_flush(false);
+
+        if (*stack_check != 0xababcdcd12123434) {
+            printf("stack overflow\n");
+            while (true);
+        }
     }
 }
 
diff --git a/mdrv_fw/usr/app_main.h b/mdrv_fw/usr/app_main.h
index 11b3fbf..09f7c44 100644
--- a/mdrv_fw/usr/app_main.h
+++ b/mdrv_fw/usr/app_main.h
@@ -10,7 +10,7 @@
 #ifndef __APP_MAIN_H__
 #define __APP_MAIN_H__
 
-#include "cdnet_dispatch.h"
+#include "cdnet_core.h"
 #include "cd_debug.h"
 #include "cdbus_uart.h"
 #include "cdctl_it.h"
@@ -222,6 +222,8 @@ extern gpio_t sen_int;
 extern cdn_ns_t dft_ns;
 extern list_head_t frame_free_head;
 
+extern uint32_t end; // end of bss
+
 
 inline void encoder_isr(void)
 {