diff --git a/Power_Pico/BSP/GATE/gate.h b/Power_Pico/BSP/GATE/gate.h
index 42f545d..0e49b85 100644
--- a/Power_Pico/BSP/GATE/gate.h
+++ b/Power_Pico/BSP/GATE/gate.h
@@ -15,11 +15,16 @@ extern "C" {
 #define EN2_PORT    GPIOA
 #define EN2_PIN     GPIO_PIN_15
 
-//
+// Flow route selection
 #define HIGH_CUR 2
 #define MID_CUR 1
 #define LOW_CUR 0
 
+// Resistance values in ohms
+#define HIGH_CUR_RES 0.005    // 5 m ohm
+#define MID_CUR_RES 0.5     // 500 m ohm
+#define LOW_CUR_RES 50.0     // 50 ohm
+
 void Gate_Port_Init(void);
 void flow_route_selection(uint8_t selection);
 uint8_t Gate_get_status(void);
diff --git a/Power_Pico/User/Tasks/Src/user_HardwareInitTask.c b/Power_Pico/User/Tasks/Src/user_HardwareInitTask.c
index 1c4c2ec..09df813 100644
--- a/Power_Pico/User/Tasks/Src/user_HardwareInitTask.c
+++ b/Power_Pico/User/Tasks/Src/user_HardwareInitTask.c
@@ -30,12 +30,12 @@
 /* protocol frame
 + 0x55 0xAA header
 + 1byte direct & unit, 0x0? for positive, 0x1? for negative,
-  0x?0 for uA (0-500.00uA), 0x?1 for mA (0.50-500.00mA), 0x?2 for A (0.50-5.00A)
-+ 2byte current (100 times)
+  0x?0 for uA (0-500.00uA), 0x?1 for uA (0.50-500.00mA), 0x?2 for mA (0.50-5.00A)
++ 4byte current (100 times)
 + 2byte voltage (100 times)
 + 0xAA 0x55 footer
 */
-uint8_t protocol_frame[] = {0x55, 0xAA, 0x02, 0x01, 0x23, 0x01, 0xf4, 0xAA, 0x55};
+uint8_t protocol_frame[] = {0x55, 0xAA, 0x02, 0x00, 0x00, 0x01, 0x23, 0x01, 0xf4, 0xAA, 0x55};
 
 /* Private function prototypes -----------------------------------------------*/
 
diff --git a/Power_Pico/User/Tasks/Src/user_SendTask.c b/Power_Pico/User/Tasks/Src/user_SendTask.c
index 2f288fa..9fa688c 100644
--- a/Power_Pico/User/Tasks/Src/user_SendTask.c
+++ b/Power_Pico/User/Tasks/Src/user_SendTask.c
@@ -4,14 +4,71 @@
 #include "main.h"
 #include "adc.h"
 #include "gate.h"
+#include "usart.h"
 /* Private typedef -----------------------------------------------------------*/
 
 /* Private define ------------------------------------------------------------*/
 
+// 定义档位阈值
+#define LOW_TO_MID_THRESHOLD 55000 // 550uA
+#define MID_TO_LOW_THRESHOLD 45000 // 450uA (滞回)
+#define MID_TO_HIGH_THRESHOLD 5000000 // 50mA
+#define HIGH_TO_MID_THRESHOLD 4500 // 45mA (滞回)
+
+// 定义连续超过阈值的次数
+#define SWITCH_COUNT_THRESHOLD 2
+
+// 切换计数器
+uint8_t low_to_mid_count = 0;
+uint8_t mid_to_low_count = 0;
+uint8_t mid_to_high_count = 0;
+uint8_t high_to_mid_count = 0;
+
 /* Private variables ---------------------------------------------------------*/
 
 /* Private function prototypes -----------------------------------------------*/
 
+// 检查当前电流并根据阈值切换流路
+void check_and_switch_flow_route(uint8_t unit, uint32_t cur) {
+  if (unit == LOW_CUR) {
+      if (cur > LOW_TO_MID_THRESHOLD) {
+          low_to_mid_count++;
+          if (low_to_mid_count >= SWITCH_COUNT_THRESHOLD) {
+              flow_route_selection(MID_CUR); // 切换到中档位
+              low_to_mid_count = 0; // 重置计数器
+          }
+      } else {
+          low_to_mid_count = 0; // 清零计数器
+      }
+  } else if (unit == MID_CUR) {
+      if (cur > MID_TO_HIGH_THRESHOLD) {
+          mid_to_high_count++;
+          if (mid_to_high_count >= SWITCH_COUNT_THRESHOLD) {
+              flow_route_selection(HIGH_CUR); // 切换到高档位
+              mid_to_high_count = 0; // 重置计数器
+          }
+      } else if (cur < MID_TO_LOW_THRESHOLD) {
+          mid_to_low_count++;
+          if (mid_to_low_count >= SWITCH_COUNT_THRESHOLD) {
+              flow_route_selection(LOW_CUR); // 切换到低档位
+              mid_to_low_count = 0; // 重置计数器
+          }
+      } else {
+          mid_to_high_count = 0; // 清零计数器
+          mid_to_low_count = 0; // 清零计数器
+      }
+  } else if (unit == HIGH_CUR) {
+      if (cur < HIGH_TO_MID_THRESHOLD) {
+          high_to_mid_count++;
+          if (high_to_mid_count >= SWITCH_COUNT_THRESHOLD) {
+              flow_route_selection(MID_CUR); // 切换到中档位
+              high_to_mid_count = 0; // 重置计数器
+          }
+      } else {
+          high_to_mid_count = 0; // 清零计数器
+      }
+  }
+}
 
 /**
   * @brief  task for send messages or data
@@ -32,25 +89,37 @@ void UartSendTask(void *argument)
     for(int i = 0 ; i < ADC_TIMES ; i++)
     {
       // direct & unit
-      uint8_t dir_unit = 0x00; // positive, uA
-      uint8_t unit = Gate_get_status(); // 0 - low current, 1 - mid current, 2 - high current
-      dir_unit |= (unit & 0x0F); // unit
+      uint8_t dir_unit = 0x00; // 0x00 means: positive, (A) unit
+      uint8_t unit = Gate_get_status(); // 0 - low current(500uA), 1 - mid current(50mA), 2 - high current(5A)
+      dir_unit = (unit & 0x0F); // unit
       // current
       uint32_t cur;
-      // voltage *100times
-      uint32_t volt = adc_buf[i][3] * 3 * 100 / 4096; // 12bit ADC, 0-4095
+      uint64_t cur_adc; // 64位避免溢出
+      // voltage = VADC/4096 * 3.0Vref * 11( this means: 1MR + 100kR)
+      uint16_t volt = adc_buf[i][3] * 3 * 11 * 100 / 4096; // 100times
       // cur direction and value
       if(adc_buf[i][2-unit] > cur_bias) {
         dir_unit |= 0x10; // negative
-        // cur *100times
-        cur = (adc_buf[i][2-unit] - cur_bias) * 3 * 100 / 4096; // 3.0 Vref, 100 times, 12bit ADC
+        cur_adc = adc_buf[i][2-unit] - cur_bias;
       }
       else {
-        // cur *100times
-        cur = (cur_bias - adc_buf[i][2-unit]) * 3 * 100 / 4096; // 3.0 Vref, 100 times, 12bit ADC
+        cur_adc = cur_bias - adc_buf[i][2-unit];
       }
+      // cur = (IADC/4096 * 3.0Vref - 1.5Vref) / 50(ina199) / R
+      if(unit == HIGH_CUR) {
+        cur = cur_adc * 3 * 100 * 1000 / HIGH_CUR_RES / 50 / 4096; // 100times. (mA)
+      }
+      else if(unit == MID_CUR) {
+        cur = cur_adc * 3 * 100 * 1000000 / MID_CUR_RES / 50 / 4096; // 100times. (uA)
+      }
+      else if(unit == LOW_CUR) {
+        cur = cur_adc * 3 * 100 * 1000000 / LOW_CUR_RES / 50 / 4096; // 100times. (uA)
+      }
+
+      check_and_switch_flow_route(unit, cur); // 检查并切换流路
+
       // protocol frame
-      uint8_t protocol_frame[9] = {0x55, 0xAA, dir_unit, (cur<<8 & 0xff), (cur & 0xff), (volt<<8 & 0xff), (volt & 0xff), 0xAA, 0x55};
+      uint8_t protocol_frame[11] = {0x55, 0xAA, dir_unit, (cur>>24 & 0xff), (cur>>16 & 0xff), (cur>>8 & 0xff), (cur & 0xff), (volt>>8 & 0xff), (volt & 0xff), 0xAA, 0x55};
       UART6_TX_Send(protocol_frame, sizeof(protocol_frame));
     }
 		osDelay(1);
diff --git a/Power_Pico/User/Tasks/Src/user_TasksInit.c b/Power_Pico/User/Tasks/Src/user_TasksInit.c
index f05e970..4b62998 100644
--- a/Power_Pico/User/Tasks/Src/user_TasksInit.c
+++ b/Power_Pico/User/Tasks/Src/user_TasksInit.c
@@ -39,7 +39,7 @@ const osThreadAttr_t HardwareInitTask_attributes = {
 osThreadId_t UartSendTaskHandle;
 const osThreadAttr_t UartSendTask_attributes = {
   .name = "UartSendTask",
-  .stack_size = 128 * 1,
+  .stack_size = 128 * 2,
   .priority = (osPriority_t) osPriorityHigh1,
 };