diff --git a/hw/boards/mta1-usb-v1/ch552_fw/include/debug.c b/hw/boards/mta1-usb-v1/ch552_fw/include/debug.c
index 4328123..7d16178 100644
--- a/hw/boards/mta1-usb-v1/ch552_fw/include/debug.c
+++ b/hw/boards/mta1-usb-v1/ch552_fw/include/debug.c
@@ -160,3 +160,44 @@ int getchar() {
     return SBUF;
 }
 #endif
+
+// Set pin p1.4 and p1.5 to GPIO output mode.
+void gpio_init(){
+	// p1.4
+	P1_MOD_OC &= ~0x10;
+	P1_DIR_PU |= 0x10;
+
+	// p1.5
+	P1_MOD_OC &= ~0x20;
+	P1_DIR_PU |= 0x20;
+
+}
+
+void gpio_set(uint8_t pin) {
+	switch (pin)
+	{
+	case 0x10: // p1.4
+		P1 |= 0x10;
+		break;
+	case 0x20: // p1.5
+		P1 |= 0x20;
+		break;
+	default: // do nothing, unsupported pin.
+		break;
+	}
+}
+
+void gpio_unset(uint8_t pin) {
+	switch (pin)
+	{
+	case 0x10:
+		P1 &= ~0x10;
+		break;
+	case 0x20:
+		P1 &= ~0x20;
+		break;
+	default: // do nothing, unsupported pin.
+		break;
+	}
+
+}
\ No newline at end of file
diff --git a/hw/boards/mta1-usb-v1/ch552_fw/include/debug.h b/hw/boards/mta1-usb-v1/ch552_fw/include/debug.h
index fc4ae39..eb0291a 100644
--- a/hw/boards/mta1-usb-v1/ch552_fw/include/debug.h
+++ b/hw/boards/mta1-usb-v1/ch552_fw/include/debug.h
@@ -177,3 +177,8 @@ inline void CH554WDTFeed(uint8_t tim)
    WDOG_COUNT = tim;                                                            // Watchdog counter assignment
 
 }
+
+// Set pin p1.4 and p1.5 to GPIO output mode.
+void gpio_init();
+void gpio_set(uint8_t pin);
+void gpio_unset(uint8_t pin);
\ No newline at end of file
diff --git a/hw/boards/mta1-usb-v1/ch552_fw/main.c b/hw/boards/mta1-usb-v1/ch552_fw/main.c
index 4d0b5ed..5ce23a6 100644
--- a/hw/boards/mta1-usb-v1/ch552_fw/main.c
+++ b/hw/boards/mta1-usb-v1/ch552_fw/main.c
@@ -573,12 +573,17 @@ main()
     UEP1_T_LEN = 0;                                                       //Pre-use send length must be cleared
     UEP2_T_LEN = 0;                                                       //Pre-use send length must be cleared
     
+    gpio_init();
+    gpio_unset(0x10);
+    gpio_unset(0x20);
+
     while(1)
     {
         if(UsbConfig)
         {
             if(USBByteCount)   // USB receiving endpoint has data
             {
+                gpio_set(0x20);
                 CH554UART1SendByte(Ep2Buffer[USBBufOutPoint++]);
                 recievedData[USBBufOutPoint] = Ep2Buffer[USBBufOutPoint];
                 USBByteCount--;
@@ -586,6 +591,7 @@ main()
                 if(USBByteCount==0)
                     UEP2_CTRL = UEP2_CTRL & ~ MASK_UEP_R_RES | UEP_R_RES_ACK;
 
+                gpio_unset(0x20);
             }
             if(UartByteCount)
                 Uart_Timeout++;
@@ -596,6 +602,7 @@ main()
                 {
                     if(length>39 || Uart_Timeout>100)
                     {
+                        gpio_set(0x10);
                         Uart_Timeout = 0;
                         if(Uart_Output_Point+length>UART_REV_LEN)
                             length = UART_REV_LEN-Uart_Output_Point;
@@ -605,12 +612,13 @@ main()
 
                         Uart_Output_Point+=length;
                         if (Uart_Output_Point>=UART_REV_LEN)
-                            Uart_Output_Point = 0;
-                        UEP2_T_LEN = length; // Pre-use send length must be cleared
-                        UEP2_CTRL = UEP2_CTRL & ~ MASK_UEP_T_RES | UEP_T_RES_ACK; // Answer ACK
-                        UpPoint2_Busy = 1;
-                    }
-                }
+                            Uart_Output_Point = 0;
+                        UEP2_T_LEN = length; // Pre-use send length must be cleared
+                        UEP2_CTRL = UEP2_CTRL & ~ MASK_UEP_T_RES | UEP_T_RES_ACK; // Answer ACK
+                        UpPoint2_Busy = 1;
+                        gpio_unset(0x10);
+                    }
+                }
             }
         }
     }