STM32 移植FreeModbus详细过程

modbus是一个非常好的串口协议(当然也能用在网口上),它简洁、规范、强大。可以满足大部分的工业、嵌入式需求。

这里详细说下如何将freemodbus移植到stm32平台。我之前下载的版本是1.5,当前官网最新的版本是1.6。两者差别不大,这里以1.5版本做演示。

1、下载好之后,解压得到如下内容:

我们需要的是modbus这个文件夹,和demo->BARE下的port文件夹。

2、准备一个STM32的工程文件夹,在工程文件夹下新建一个文件夹:FreeModbus。将第一步获取的两个文件夹放到里面。

打开工程,添加两个group,名字分别为modbus和port。将这两个文件夹下的C文件都添加进来,tcp相关的除外。

文件包含路径,也添加这几个文件夹的位置:

3、完善portserial.c文件。该文件就是modbus通信中用到的串口的初始化配置文件。我这里选择usart1,波特率9600.

第一次打开这个文件,内容如下:

void
vMBPortSerialEnable( BOOL xRxEnable, BOOL xTxEnable )
{
    /* If xRXEnable enable serial receive interrupts. If xTxENable enable
     * transmitter empty interrupts.
     */
}

BOOL
xMBPortSerialInit( UCHAR ucPORT, ULONG ulBaudRate, UCHAR ucDataBits, eMBParity eParity )
{
    return FALSE;
}

BOOL
xMBPortSerialPutByte( CHAR ucByte )
{
    /* Put a byte in the UARTs transmit buffer. This function is called
     * by the protocol stack if pxMBFrameCBTransmitterEmpty( ) has been
     * called. */
    return TRUE;
}

认真看一下函数名字,你会发现这些函数分别是:串口使能、串口初始化、发送一个字节、接收一个字节等等。

完善后代码如下:

/* ----------------------- Start implementation -----------------------------*/
void
vMBPortSerialEnable( BOOL xRxEnable, BOOL xTxEnable )
{
    /* If xRXEnable enable serial receive interrupts. If xTxENable enable
     * transmitter empty interrupts.
     */
	if(xRxEnable == TRUE)
	{
		USART_ITConfig(USART1, USART_IT_RXNE, ENABLE);
	}
	else
	{
		USART_ITConfig(USART1, USART_IT_RXNE, DISABLE);
	}
	
	if(xTxEnable == TRUE)
	{
		USART_ITConfig(USART1, USART_IT_TC, ENABLE);
	}
	else
	{
		USART_ITConfig(USART1, USART_IT_TC, DISABLE);
	}
}

BOOL
xMBPortSerialInit( UCHAR ucPORT, ULONG ulBaudRate, UCHAR ucDataBits, eMBParity eParity )
{
  USART1_Config((uint16_t)ulBaudRate);  
	USART_NVIC();
	return TRUE;
}

BOOL
xMBPortSerialPutByte( CHAR ucByte )
{
    /* Put a byte in the UARTs transmit buffer. This function is called
     * by the protocol stack if pxMBFrameCBTransmitterEmpty( ) has been
     * called. */
	
		USART_SendData(USART1, ucByte);
    return TRUE;
}

BOOL
xMBPortSerialGetByte( CHAR * pucByte )
{
    /* Return the byte in the UARTs receive buffer. This function is called
     * by the protocol stack after pxMBFrameCBByteReceived( ) has been called.
     */
  *pucByte = USART_ReceiveData(USART1); 
	return TRUE;
}

/* Create an interrupt handler for the transmit buffer empty interrupt
 * (or an equivalent) for your target processor. This function should then
 * call pxMBFrameCBTransmitterEmpty( ) which tells the protocol stack that
 * a new character can be sent. The protocol stack will then call 
 * xMBPortSerialPutByte( ) to send the character.
 */
static void prvvUARTTxReadyISR( void )
{
    pxMBFrameCBTransmitterEmpty(  );
}

/* Create an interrupt handler for the receive interrupt for your target
 * processor. This function should then call pxMBFrameCBByteReceived( ). The
 * protocol stack will then call xMBPortSerialGetByte( ) to retrieve the
 * character.
 */
static void prvvUARTRxISR( void )
{
    pxMBFrameCBByteReceived(  );
}

/**
  * @brief  This function handles usart1 Handler.
  * @param  None
  * @retval None
  */
void USART1_IRQHandler(void)
{
  //发生接收中断
  if(USART_GetITStatus(USART1, USART_IT_RXNE) == SET)
  {
    prvvUARTRxISR(); 
    //清除中断标志位    
    USART_ClearITPendingBit(USART1, USART_IT_RXNE);   
  }
	
	if(USART_GetITStatus(USART1, USART_IT_ORE) == SET)
  {  
    USART_ClearITPendingBit(USART1, USART_IT_ORE);
		prvvUARTRxISR(); 	
  }
  
  //发生完成中断
  if(USART_GetITStatus(USART1, USART_IT_TC) == SET)
  {
    prvvUARTTxReadyISR();
    //清除中断标志
    USART_ClearITPendingBit(USART1, USART_IT_TC);
  }
}

其中USART1_Config((uint16_t)ulBaudRate);和    USART_NVIC();是串口初始化的代码,如下:

/**
  * @brief  USART1 GPIO 配置,工作模式配置。9600 8-N-1
  * @param  无
  * @retval 无
  */
void USART1_Config(uint16_t buad)
{
		GPIO_InitTypeDef GPIO_InitStructure;
		USART_InitTypeDef USART_InitStructure;
		
		/* config USART1 clock */
		RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1 | RCC_APB2Periph_GPIOA, ENABLE);
		
		/* USART1 GPIO config */
		/* Configure USART1 Tx (PA.09) as alternate function push-pull */
		GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9;
		GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
		GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
		GPIO_Init(GPIOA, &GPIO_InitStructure);    
		/* Configure USART1 Rx (PA.10) as input floating */
		GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10;
		GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
		GPIO_Init(GPIOA, &GPIO_InitStructure);
			
		/* USART1 mode config */
		USART_InitStructure.USART_BaudRate = buad;
		USART_InitStructure.USART_WordLength = USART_WordLength_8b;
		USART_InitStructure.USART_StopBits = USART_StopBits_1;
		USART_InitStructure.USART_Parity = USART_Parity_No ;
		USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
		USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;
		//USART_ITConfig(USART2,USART_IT_RXNE,ENABLE);
		USART_Init(USART1, &USART_InitStructure); 
		USART_Cmd(USART1, ENABLE);
}

/**
  * @brief  USART1 中断 配置
  * @param  无
  * @retval 无
  */
void USART_NVIC(void)
{
  NVIC_InitTypeDef NVIC_InitStructure;
  
  /* Configure one bit for preemption priority */
  NVIC_PriorityGroupConfig(NVIC_PriorityGroup_0);
  
  /* 配置中断源 */
  NVIC_InitStructure.NVIC_IRQChannel = USART1_IRQn;
  NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
  NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
  NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
  NVIC_Init(&NVIC_InitStructure);
}

 

4、然后是porttimer.c文件,modbus工作时需要一个定时器,所以这里配置一个定时器。定时器时基是50us,周期做为参数输入。代码如下:

/* ----------------------- Start implementation -----------------------------*/
BOOL
xMBPortTimersInit( USHORT usTim1Timerout50us )
{
  timer2_init(usTim1Timerout50us);
	timer2_nvic();
	return TRUE;
}


void
vMBPortTimersEnable(  )
{
    /* Enable the timer with the timeout passed to xMBPortTimersInit( ) */
	TIM_ClearITPendingBit(TIM2, TIM_IT_Update);
  TIM_ITConfig(TIM2, TIM_IT_Update, ENABLE);
  TIM_SetCounter(TIM2,0x0000); 
	TIM_Cmd(TIM2, ENABLE);
}

void
vMBPortTimersDisable(  )
{
    /* Disable any pending timers. */
  TIM_ClearITPendingBit(TIM2, TIM_IT_Update);
  TIM_ITConfig(TIM2, TIM_IT_Update, DISABLE);
  TIM_SetCounter(TIM2,0x0000); 
  TIM_Cmd(TIM2, DISABLE);
}

/* Create an ISR which is called whenever the timer has expired. This function
 * must then call pxMBPortCBTimerExpired( ) to notify the protocol stack that
 * the timer has expired.
 */
static void prvvTIMERExpiredISR( void )
{
    ( void )pxMBPortCBTimerExpired(  );
}

void TIM2_IRQHandler(void)
{
	if(TIM_GetITStatus(TIM2, TIM_IT_Update) != RESET)
	{
		prvvTIMERExpiredISR();
		TIM_ClearITPendingBit(TIM2, TIM_IT_Update);
	}
}

其中 timer2_init(usTim1Timerout50us) 和 timer2_nvic() 是timer2初始化函数,内容如下:

void timer2_init(uint16_t period)
{
	TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
	RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);
        TIM_DeInit(TIM2);
	TIM_TimeBaseStructure.TIM_Period = period;
        TIM_TimeBaseStructure.TIM_Prescaler = (1800 - 1);	
	TIM_TimeBaseStructure.TIM_ClockDivision = 0;
	TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
	TIM_TimeBaseInit(TIM2, &TIM_TimeBaseStructure);
	TIM_Cmd(TIM2, ENABLE);

}

void timer2_nvic(void)
{
	NVIC_InitTypeDef NVIC_InitStructure;
	NVIC_InitStructure.NVIC_IRQChannel = TIM2_IRQn;
        NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
        NVIC_InitStructure.NVIC_IRQChannelSubPriority = 2;
	NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;	
	NVIC_Init(&NVIC_InitStructure);	
}

5、在main.c文件中,定义各个模拟寄存器的地址和大小。

//输入寄存器起始地址

#define REG_INPUT_START 0x0000

//输入寄存器数量

#define REG_INPUT_NREGS 8

//保持寄存器起始地址

#define REG_HOLDING_START 0x0000

//保持寄存器数量

#define REG_HOLDING_NREGS 8

//线圈起始地址

#define REG_COILS_START 0x0000

//线圈数量

#define REG_COILS_SIZE 16

//开关寄存器起始地址

#define REG_DISCRETE_START 0x0000

//开关寄存器数量

#define REG_DISCRETE_SIZE 16

6、补全输入寄存器操作函数、保持寄存器操作函数。modbus功能进行初始化,设置地址和波特率。这部分内容可以参考官方资料里的例程,也可以直接复制别人写好的。我这里放别人写好的代码:

/**
  * @brief  主函数
  * @param  无
  * @retval 无
  */
int main(void)
{
		usRegInputBuf[0] = 'I';
		usRegInputBuf[1] = ' ';
		usRegInputBuf[2] = 'a';
		usRegInputBuf[3] = 'm';
		usRegInputBuf[4] = ' ';
		usRegInputBuf[5] = 'I';
	

		RCC_Config();
		eMBInit(MB_RTU, 0x01, 0x01, 9600, MB_PAR_NONE);
		eMBEnable();   
		for(;;)
		{
			(void)eMBPoll();
		}
}

//static void Delay(__IO uint32_t nCount)	 //简单的延时函数
//{
//	for(; nCount != 0; nCount--);
//}
/*********************************************END OF FILE**********************/

/****************************************************************************
* 名	  称:eMBRegInputCB 
* 功    能:读取输入寄存器,对应功能码是 04 eMBFuncReadInputRegister
* 入口参数:pucRegBuffer: 数据缓存区,用于响应主机   
*						usAddress: 寄存器地址
*						usNRegs: 要读取的寄存器个数
* 出口参数:
* 注	  意:上位机发来的 帧格式是: SlaveAddr(1 Byte)+FuncCode(1 Byte)
*								+StartAddrHiByte(1 Byte)+StartAddrLoByte(1 Byte)
*								+LenAddrHiByte(1 Byte)+LenAddrLoByte(1 Byte)+
*								+CRCAddrHiByte(1 Byte)+CRCAddrLoByte(1 Byte)
*							3 区
****************************************************************************/
eMBErrorCode
eMBRegInputCB( UCHAR * pucRegBuffer, USHORT usAddress, USHORT usNRegs )
{
    eMBErrorCode    eStatus = MB_ENOERR;
    int             iRegIndex;

    if( ( usAddress >= REG_INPUT_START )
        && ( usAddress + usNRegs <= REG_INPUT_START + REG_INPUT_NREGS ) )
    {
        iRegIndex = ( int )( usAddress - usRegInputStart );
        while( usNRegs > 0 )
        {
            *pucRegBuffer++ = ( UCHAR )( usRegInputBuf[iRegIndex] >> 8 );
            *pucRegBuffer++ = ( UCHAR )( usRegInputBuf[iRegIndex] & 0xFF );
            iRegIndex++;
            usNRegs--;
        }
    }
    else
    {
        eStatus = MB_ENOREG;
    }

    return eStatus;
}

/****************************************************************************
* 名	  称:eMBRegHoldingCB 
* 功    能:对应功能码有:06 写保持寄存器 eMBFuncWriteHoldingRegister 
*													16 写多个保持寄存器 eMBFuncWriteMultipleHoldingRegister
*													03 读保持寄存器 eMBFuncReadHoldingRegister
*													23 读写多个保持寄存器 eMBFuncReadWriteMultipleHoldingRegister
* 入口参数:pucRegBuffer: 数据缓存区,用于响应主机   
*						usAddress: 寄存器地址
*						usNRegs: 要读写的寄存器个数
*						eMode: 功能码
* 出口参数:
* 注	  意:4 区
****************************************************************************/
eMBErrorCode
eMBRegHoldingCB( UCHAR * pucRegBuffer, USHORT usAddress, USHORT usNRegs, eMBRegisterMode eMode )
{
	eMBErrorCode    eStatus = MB_ENOERR;
	int             iRegIndex;


	if((usAddress >= REG_HOLDING_START)&&\
		((usAddress+usNRegs) <= (REG_HOLDING_START + REG_HOLDING_NREGS)))
	{
		iRegIndex = (int)(usAddress - usRegHoldingStart);
		switch(eMode)
		{                                       
			case MB_REG_READ://读 MB_REG_READ = 0
        while(usNRegs > 0)
				{
					*pucRegBuffer++ = (u8)(usRegHoldingBuf[iRegIndex] >> 8);            
					*pucRegBuffer++ = (u8)(usRegHoldingBuf[iRegIndex] & 0xFF); 
          iRegIndex++;
          usNRegs--;					
				}                            
        break;
			case MB_REG_WRITE://写 MB_REG_WRITE = 0
				while(usNRegs > 0)
				{         
					usRegHoldingBuf[iRegIndex] = *pucRegBuffer++ << 8;
          usRegHoldingBuf[iRegIndex] |= *pucRegBuffer++;
          iRegIndex++;
          usNRegs--;
        }				
			}
	}
	else//错误
	{
		eStatus = MB_ENOREG;
	}	
	
	return eStatus;
}

/****************************************************************************
* 名	  称:eMBRegCoilsCB 
* 功    能:对应功能码有:01 读线圈 eMBFuncReadCoils
*													05 写线圈 eMBFuncWriteCoil
*													15 写多个线圈 eMBFuncWriteMultipleCoils
* 入口参数:pucRegBuffer: 数据缓存区,用于响应主机   
*						usAddress: 线圈地址
*						usNCoils: 要读写的线圈个数
*						eMode: 功能码
* 出口参数:
* 注	  意:如继电器 
*						0 区
****************************************************************************/
eMBErrorCode
eMBRegCoilsCB( UCHAR * pucRegBuffer, USHORT usAddress, USHORT usNCoils, eMBRegisterMode eMode )
{
	eMBErrorCode    eStatus = MB_ENOERR;
	int             iRegIndex;


	if((usAddress >= REG_HOLDING_START)&&\
		((usAddress+usNCoils) <= (REG_HOLDING_START + REG_HOLDING_NREGS)))
	{
		iRegIndex = (int)(usAddress - usRegHoldingStart);
		switch(eMode)
		{                                       
			case MB_REG_READ://读 MB_REG_READ = 0
        while(usNCoils > 0)
				{
// 					*pucRegBuffer++ = (u8)(usRegHoldingBuf[iRegIndex] >> 8);            
// 					*pucRegBuffer++ = (u8)(usRegHoldingBuf[iRegIndex] & 0xFF); 
          iRegIndex++;
          usNCoils--;					
				}                            
        break;
			case MB_REG_WRITE://写 MB_REG_WRITE = 1
				while(usNCoils > 0)
				{         
// 					usRegHoldingBuf[iRegIndex] = *pucRegBuffer++ << 8;
//           usRegHoldingBuf[iRegIndex] |= *pucRegBuffer++;
          iRegIndex++;
          usNCoils--;
        }				
			}
	}
	else//错误
	{
		eStatus = MB_ENOREG;
	}	
	
	return eStatus;
}
/****************************************************************************
* 名	  称:eMBRegDiscreteCB 
* 功    能:读取离散寄存器,对应功能码有:02 读离散寄存器 eMBFuncReadDiscreteInputs
* 入口参数:pucRegBuffer: 数据缓存区,用于响应主机   
*						usAddress: 寄存器地址
*						usNDiscrete: 要读取的寄存器个数
* 出口参数:
* 注	  意:1 区
****************************************************************************/
eMBErrorCode
eMBRegDiscreteCB( UCHAR * pucRegBuffer, USHORT usAddress, USHORT usNDiscrete )
{
    ( void )pucRegBuffer;
    ( void )usAddress;
    ( void )usNDiscrete;
    return MB_ENOREG;
}

7、修改mbrtu.c文件,否则modbus从机收到命令后,只会返回一次数据。在函数“eMBRTUSend”中。

eMBErrorCode
eMBRTUSend( UCHAR ucSlaveAddress, const UCHAR * pucFrame, USHORT usLength )
{
    eMBErrorCode    eStatus = MB_ENOERR;
    USHORT          usCRC16;

    ENTER_CRITICAL_SECTION(  );

    /* Check if the receiver is still in idle state. If not we where to
     * slow with processing the received frame and the master sent another
     * frame on the network. We have to abort sending the frame.
     */
    if( eRcvState == STATE_RX_IDLE )
    {
        /* First byte before the Modbus-PDU is the slave address. */
        pucSndBufferCur = ( UCHAR * ) pucFrame - 1;
        usSndBufferCount = 1;

        /* Now copy the Modbus-PDU into the Modbus-Serial-Line-PDU. */
        pucSndBufferCur[MB_SER_PDU_ADDR_OFF] = ucSlaveAddress;
        usSndBufferCount += usLength;

        /* Calculate CRC16 checksum for Modbus-Serial-Line-PDU. */
        usCRC16 = usMBCRC16( ( UCHAR * ) pucSndBufferCur, usSndBufferCount );
        ucRTUBuf[usSndBufferCount++] = ( UCHAR )( usCRC16 & 0xFF );
        ucRTUBuf[usSndBufferCount++] = ( UCHAR )( usCRC16 >> 8 );

        /* Activate the transmitter. */
        //发送状态转换,在中断中不断发送
        eSndState = STATE_TX_XMIT;
        
        //启动第一次发送,这样才可以进入发送完成中断
        xMBPortSerialPutByte( ( CHAR )*pucSndBufferCur );
        pucSndBufferCur++;  /* next byte in sendbuffer. */
        usSndBufferCount--;
        
        //使能发送状态,禁止接收状态
        vMBPortSerialEnable( FALSE, TRUE );
    }
    else
    {
        eStatus = MB_EIO;
    }
    EXIT_CRITICAL_SECTION(  );
    return eStatus;
}

 8、修改mbconfig.h文件,取消对ASCII的支持。

#define MB_ASCII_ENABLED                        (  0 )

9、保存,编译,下载。使用专用的modbus工具测试。工具配置如下:

modbus指令格式如下:

咱们这里设置如下:01 04 00 00 00 02,功能码04,起始地址0,数据长度2.校验码没有写怎么办?

这就是这个工具的便利之处!我们不用管,它会自动计算!直接点击发送即可。得到结果如下:

可以看到下面的框里,绿色的是我们发送的内容,最后两位是工具自动补上的。蓝色内容是单片机(也就是modbus从机)返回给我们的。

没有问题,打完收工!

工程模版和modbus工具,我上传到了公众号:单片机爱好者,回复关键词:modbus,即可获取。

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