diff --git a/main/ble_spp_client_demo.c b/main/ble_spp_client_demo.c
index 4387039..40f14ff 100644
--- a/main/ble_spp_client_demo.c
+++ b/main/ble_spp_client_demo.c
@@ -693,14 +693,14 @@ void ble_init()
     spp_uart_init();
 }
 
-void ble_gattc_write_char_cb(char* string)
+void ble_gattc_write_char_cb(char *string, uint8_t string_length)
 {
     if ((is_connect == true) && (db != NULL) && ((db + SPP_IDX_SPP_DATA_RECV_VAL)->properties & (ESP_GATT_CHAR_PROP_BIT_WRITE_NR | ESP_GATT_CHAR_PROP_BIT_WRITE)))
     {
         esp_ble_gattc_write_char(spp_gattc_if,
                                  spp_conn_id,
                                  (db + SPP_IDX_SPP_DATA_RECV_VAL)->attribute_handle,
-                                 strlen(string),
+                                 string_length,
                                  (uint8_t *)string,
                                  ESP_GATT_WRITE_TYPE_RSP,
                                  ESP_GATT_AUTH_REQ_NONE);
diff --git a/main/ble_spp_client_demo.h b/main/ble_spp_client_demo.h
index c20bb51..6a018c9 100644
--- a/main/ble_spp_client_demo.h
+++ b/main/ble_spp_client_demo.h
@@ -22,7 +22,7 @@ enum
 
     SPP_IDX_SPP_DATA_RECV_VAL,
 
-    // SPP_IDX_SPP_COMMAND_VAL,
+// SPP_IDX_SPP_COMMAND_VAL,
 
 #ifdef SUPPORT_HEARTBEAT
     SPP_IDX_SPP_HEARTBEAT_VAL,
@@ -33,4 +33,4 @@ enum
 };
 
 void ble_init();
-void ble_gattc_write_char_cb();
\ No newline at end of file
+void ble_gattc_write_char_cb(char *string, uint8_t string_length);
\ No newline at end of file
diff --git a/main/key.c b/main/key.c
index 49a0fae..8afca72 100644
--- a/main/key.c
+++ b/main/key.c
@@ -22,21 +22,23 @@ void key_schedule()
     if (gpio_get_level(KEY_REC) == 0)
     {
         /* code */
+        char *send_string = "{ \"order\": \"setPosition\", \"index\": 0, \"speedLevel\": 0, \"position\": 360, \"direction\": 1 }";
         ESP_LOGI("Finny", "KEY_REC level 0");
         while (gpio_get_level(KEY_REC) == 0)
         {
         }
-        s_ble_gattc_write_char_cb("{ \"order\": \"setPosition\", \"index\": 0, \"speedLevel\": 0, \"position\": 180, \"direction\": 1 }");
+        s_ble_gattc_write_char_cb(send_string, strlen(send_string));
         ESP_LOGI("Finny", "stop");
     }
     if (gpio_get_level(KEY_MODE) == 0)
     {
+        char *send_string = "{ \"order\": \"setPosition\", \"index\": 0, \"speedLevel\": 0, \"position\": 360, \"direction\": 1 }";
         /* code */
         ESP_LOGI("Finny", "KEY_MODE level 0");
         while (gpio_get_level(KEY_MODE) == 0)
         {
         }
-        s_ble_gattc_write_char_cb("{ \"order\": \"setPosition\", \"index\": 0, \"speedLevel\": 0, \"position\": 360, \"direction\": 1 }");
+        s_ble_gattc_write_char_cb(send_string, strlen(send_string));
         ESP_LOGI("Finny", "stop");
     }
 }
diff --git a/main/key.h b/main/key.h
index 213d4cb..f89293d 100644
--- a/main/key.h
+++ b/main/key.h
@@ -7,7 +7,7 @@
 #define KEY_MODE 39
 #define GPIO_KEY_INPUT_PIN_SEL ((1ULL << KEY_REC) | (1ULL << KEY_MODE))
 
-typedef void (*key_ble_cb_t)(char* string);
+typedef void (*key_ble_cb_t)(char *string, uint8_t string_length);
 
 void key_init();
 void key_schedule();
diff --git a/main/main.c b/main/main.c
index cc111d5..dfd3cd4 100644
--- a/main/main.c
+++ b/main/main.c
@@ -45,7 +45,7 @@ void pc_uart_receive(uart_port_t uart_num)
     if (length != 0)
     {
         length = uart_read_bytes(uart_num, rx_data_buffer, length, 100);
-        uart_write_bytes(UART_NUM_2, rx_data_buffer, length);
+        ble_gattc_write_char_cb((char *)rx_data_buffer, length);
     }
 }