diff --git a/BSP/inc/bsp.h b/BSP/inc/bsp.h
index f2b4de0..2d57885 100644
--- a/BSP/inc/bsp.h
+++ b/BSP/inc/bsp.h
@@ -43,7 +43,7 @@
 
 // <o> Internal SRAM memory size[Kbytes] <8-64>
 //	<i>Default: 64
-#define STM32_SRAM_SIZE         64
+#define STM32_SRAM_SIZE         20
 #define STM32_SRAM_END          (0x20000000 + STM32_SRAM_SIZE * 1024)
 
 
diff --git a/FreeModbus/modbus/rtu/mbrtu_m.c b/FreeModbus/modbus/rtu/mbrtu_m.c
index 1629f39..0460b37 100644
--- a/FreeModbus/modbus/rtu/mbrtu_m.c
+++ b/FreeModbus/modbus/rtu/mbrtu_m.c
@@ -160,7 +160,7 @@ eMBMasterRTUReceive( UCHAR * pucRcvAddress, UCHAR ** pucFrame, USHORT * pusLengt
     eMBErrorCode    eStatus = MB_ENOERR;
 
     ENTER_CRITICAL_SECTION(  );
-    assert_param( usRcvBufferPos < MB_SER_PDU_SIZE_MAX );
+    assert_param( usMasterRcvBufferPos < MB_SER_PDU_SIZE_MAX );
 
     /* Length and CRC check */
     if( ( usMasterRcvBufferPos >= MB_SER_PDU_SIZE_MIN )
@@ -235,7 +235,7 @@ xMBMasterRTUReceiveFSM( void )
     BOOL            xTaskNeedSwitch = FALSE;
     UCHAR           ucByte;
 
-    assert_param( eSndState == STATE_TX_IDLE );
+    assert_param( eSndState == STATE_M_TX_IDLE );
 
     /* Always read the character. */
     ( void )xMBMasterPortSerialGetByte( ( CHAR * ) & ucByte );
@@ -301,7 +301,7 @@ xMBMasterRTUTransmitFSM( void )
 {
     BOOL            xNeedPoll = FALSE;
 
-    assert_param( eRcvState == STATE_RX_IDLE );
+    assert_param( eRcvState == STATE_M_RX_IDLE );
 
     switch ( eSndState )
     {
diff --git a/FreeModbus/port/portserial.c b/FreeModbus/port/portserial.c
index 1e9cfa1..32067c4 100644
--- a/FreeModbus/port/portserial.c
+++ b/FreeModbus/port/portserial.c
@@ -183,7 +183,6 @@ void USART1_IRQHandler(void)
 	//·¢ËÍÖжÏ
 	if (USART_GetITStatus(USART1, USART_IT_TXE) == SET)
 	{
-		USART_ClearITPendingBit(USART1, USART_IT_TXE);
 		prvvUARTTxReadyISR();
 	}
 	rt_interrupt_leave();
diff --git a/FreeModbus/port/portserial_m.c b/FreeModbus/port/portserial_m.c
index ddbb70a..fa062b7 100644
--- a/FreeModbus/port/portserial_m.c
+++ b/FreeModbus/port/portserial_m.c
@@ -184,7 +184,6 @@ void USART2_IRQHandler(void)
 	//·¢ËÍÖжÏ
 	if (USART_GetITStatus(USART2, USART_IT_TXE) == SET)
 	{
-		USART_ClearITPendingBit(USART2, USART_IT_TXE);
 		prvvUARTTxReadyISR();
 	}
 	rt_interrupt_leave();