diff --git a/bsp/stm32f107/drivers/usart.c b/bsp/stm32f107/drivers/usart.c
index 6380f03bdf..89528d54bc 100644
--- a/bsp/stm32f107/drivers/usart.c
+++ b/bsp/stm32f107/drivers/usart.c
@@ -184,7 +184,7 @@ void USART1_IRQHandler(void)
     }
     if (USART_GetFlagStatus(uart->uart_device, USART_FLAG_ORE) == SET)
     {
-        stm32_getc(&serial1);
+        USART_ReceiveData(uart->uart_device);
     }
     /* leave interrupt */
     rt_interrupt_leave();
@@ -221,7 +221,7 @@ void USART2_IRQHandler(void)
     }
     if (USART_GetFlagStatus(uart->uart_device, USART_FLAG_ORE) == SET)
     {
-        stm32_getc(&serial2);
+        USART_ReceiveData(uart->uart_device);
     }
 
     /* leave interrupt */
diff --git a/bsp/stm32f10x/drivers/usart.c b/bsp/stm32f10x/drivers/usart.c
index 898a0135c8..65a05c3afe 100644
--- a/bsp/stm32f10x/drivers/usart.c
+++ b/bsp/stm32f10x/drivers/usart.c
@@ -270,7 +270,7 @@ static void uart_isr(struct rt_serial_device *serial) {
     }
     if (USART_GetFlagStatus(uart->uart_device, USART_FLAG_ORE) == SET)
     {
-        stm32_getc(serial);
+        USART_ReceiveData(uart->uart_device);
     }
 }
 
diff --git a/bsp/stm32f40x/drivers/usart.c b/bsp/stm32f40x/drivers/usart.c
index 0838d214e2..03d8c23235 100644
--- a/bsp/stm32f40x/drivers/usart.c
+++ b/bsp/stm32f40x/drivers/usart.c
@@ -310,7 +310,7 @@ static void uart_isr(struct rt_serial_device *serial)
     }
     if (USART_GetFlagStatus(uart->uart_device, USART_FLAG_ORE) == SET)
     {
-        stm32_getc(serial);
+        USART_ReceiveData(uart->uart_device);
     }
 }
 
diff --git a/components/net/freemodbus/modbus/rtu/mbrtu.c b/components/net/freemodbus/modbus/rtu/mbrtu.c
index c7e07826b9..40c29348ce 100644
--- a/components/net/freemodbus/modbus/rtu/mbrtu.c
+++ b/components/net/freemodbus/modbus/rtu/mbrtu.c
@@ -153,7 +153,7 @@ eMBRTUReceive( UCHAR * pucRcvAddress, UCHAR ** pucFrame, USHORT * pusLength )
     eMBErrorCode    eStatus = MB_ENOERR;
 
     ENTER_CRITICAL_SECTION(  );
-    RT_ASSERT( usRcvBufferPos < MB_SER_PDU_SIZE_MAX );
+    RT_ASSERT( usRcvBufferPos <= MB_SER_PDU_SIZE_MAX );
 
     /* Length and CRC check */
     if( ( usRcvBufferPos >= MB_SER_PDU_SIZE_MIN )