在网上关于STM32F103+FreeModbus 的Modbus RTU从站移植的移植有很多，在此记录一下自己在野火的指南者开发板上基于FreeModbus的Modbus RTU从站的过程。
硬件准备
野火指南者（STM32F103VET6）
软件准备
1、freeModbus-v1.6
2、指南者开发板工程模板（随便一个工程都可以，我习惯用一个移植好库函数的空白工程模板）
工程准备工作
1、…\freemodbus-master\freemodbus-master\demo\BARE\port中的四个文件port.h、portevent.c、portserial.c、porttimer.c是移植FreeModbus主要修改的文件，需要这四个文件放到自己的工程文件中
2、将…freemodbus-master\freemodbus-master\modbus中的所有.c文件全部添加到项目中
3、在项目路径中添加所有.c、.h文件路径
这是我的项目结构图
移植FreeModbus需要修改的文件
port.h
port.h的修改主要补充两个关于控制器开关总中断的两个宏定义
#define ENTER_CRITICAL_SECTION( ) __set_PRIMASK(1);//关总中断
#define EXIT_CRITICAL_SECTION( ) __set_PRIMASK(0);//开总中断
补充一下
__set_PRIMASK（）这个函数在core_cm3.c里面定义
具体函数定义：
/**
* @brief Set the Priority Mask value
*
* @param priMask PriMask
*
* Set the priority mask bit in the priority mask register
*/
__ASM void __set_PRIMASK(uint32_t priMask)
{
msr primask, r0
bx lr
}
portserial.c
portserial.c文件主要是串口相关函数
//该函数用于RS485接收/发送状态的切换
void vMBPortSerialEnable(BOOL xRxEnable, BOOL xTxEnable)
{
/* If xRXEnable enable serial receive interrupts. If xTxENable enable
* transmitter empty interrupts.
*/
//接收使能
if (xRxEnable == TRUE)
{
//MODBUS_RECIEVE();使用485时使用该函数将485芯片更改为接收状态
if (USART_GetFlagStatus(USART1, USART_FLAG_RXNE) == SET)
{
USART_ClearFlag(USART1, USART_FLAG_RXNE);
}
USART_ITConfig(USART1, USART_IT_RXNE, ENABLE);
}
else if (xRxEnable == FALSE)
{
//MODBUS_SEND();使用485时使用该函数将485芯片更改为发送状态
USART_ITConfig(USART1, USART_IT_RXNE, DISABLE);
}
//发送使能
if (xTxEnable == TRUE)
{
//MODBUS_SEND();使用485时使用该函数将485芯片更改为发送状态
if (USART_GetFlagStatus(USART1, USART_FLAG_TC) == SET)
{
USART_ClearFlag(USART1, USART_FLAG_TC);
}
USART_ITConfig(USART1, USART_IT_TC, ENABLE);
}
else if (xTxEnable == FALSE)
{
//MODBUS_RECIEVE();使用485时使用该函数将485芯片更改为接收状态
USART_ITConfig(USART1, USART_IT_TC, DISABLE);
}
}
//该函数用于串口的初始化，要根据工程实际使用的板子进行初始化
//如果加上485的话还要在代码里面增加485芯片发送/接收使能引脚的驱动代码
BOOL xMBPortSerialInit(UCHAR ucPORT, ULONG ulBaudRate, UCHAR ucDataBits, eMBParity eParity)
{
GPIO_InitTypeDef GPIO_InitStructure;
USART_InitTypeDef USART_InitStructure;
// 串口中断优先级配置
NVIC_InitTypeDef NVIC_InitStructure;
// 打开串口GPIO的时钟
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE);
// 打开串口外设的时钟
RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1, ENABLE);
// 将USART Tx的GPIO配置为推挽复用模式
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);
// 将USART Rx的GPIO配置为浮空输入模式
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
GPIO_Init(GPIOA, &GPIO_InitStructure);
// 配置串口的工作参数
// 配置波特率
USART_InitStructure.USART_BaudRate = 9600;
// 配置 针数据字长
USART_InitStructure.USART_WordLength = USART_WordLength_8b;
// 配置停止位
USART_InitStructure.USART_StopBits = USART_StopBits_1;
// 配置校验位
USART_InitStructure.USART_Parity = USART_Parity_No;
// 配置硬件流控制
USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
// 配置工作模式，收发一起
USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx;
// 完成串口的初始化配置
USART_Init(USART1, &USART_InitStructure);
/* 嵌套向量中断控制器组选择 */
NVIC_PriorityGroupConfig(NVIC_PriorityGroup_0);
/* 配置USART为中断源 */
NVIC_InitStructure.NVIC_IRQChannel = USART1_IRQn;
/* 抢断优先级*/
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 1;
/* 子优先级 */
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 1;
/* 使能中断 */
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
/* 初始化配置NVIC */
NVIC_Init(&NVIC_InitStructure);
// 使能串口接收中断
USART_ITConfig(USART1, USART_IT_RXNE, ENABLE);
// 使能串口
USART_Cmd(USART1, ENABLE);
return TRUE;
}
//该函数用于向串口发送一个字节的数据，这里直接使用库函数即可
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;
}
//该函数用于从串口接收一个字节的数据，这里直接调用库函数即可
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;
}
prvvUARTTxReadyISR（）和prvvUARTRxISR（）两个函数不需要更改，这两个函数需要串口中断中调用。
/* 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();
}
最后一个是串口的中断服务函数，为了方便管理我把串口的中断服务函数写在了portserial.c这个文件里面。因为指南者的usart1连接的是TTL转USB，所以我在这个工程里面使用的是usart1
void USART1_IRQHandler(void)
{
if (USART_GetITStatus(USART1, USART_IT_RXNE) != RESET)
{
prvvUARTRxISR();//在串口接收中断，调用FreeModbus的prvvUARTRxISR()函数
USART_ClearITPendingBit(USART1, USART_IT_RXNE);
}
if (USART_GetITStatus(USART1, USART_IT_TC) != RESET)
{
prvvUARTTxReadyISR();//在串口发送中断中，调用FreeModbus的prvvUARTTxReadyISR()函数
USART_ClearITPendingBit(USART1, USART_IT_TC);
}
}
至此portserial.c文件移植修改完毕。
porttimer.c
//该函数用于初始化定时器
//需要初始化一个定时时间为50us的定时器
//处理器设定主频为72MHz
//这里用到了F103的基本定时器TIM6
BOOL xMBPortTimersInit(USHORT usTim1Timerout50us)
{
TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
NVIC_InitTypeDef NVIC_InitStructure;
RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM6, ENABLE);
// 自动重装载寄存器的值，累计TIM_Period+1个频率后产生一个更新或者中断 计时器计数1次为50us
TIM_TimeBaseStructure.TIM_Period = usTim1Timerout50us;
// 时钟预分频数为50us
TIM_TimeBaseStructure.TIM_Prescaler = 3600 - 1;
// 时钟分频因子 ，基本定时器没有，不用管
//TIM_TimeBaseStructure.TIM_ClockDivision=TIM_CKD_DIV1;
// 计数器计数模式，基本定时器只能向上计数，没有计数模式的设置
//TIM_TimeBaseStructure.TIM_CounterMode=TIM_CounterMode_Up;
// 重复计数器的值，基本定时器没有，不用管
//TIM_TimeBaseStructure.TIM_RepetitionCounter=0;
// 初始化定时器
TIM_TimeBaseInit(TIM6, &TIM_TimeBaseStructure);
// 清除计数器中断标志位
TIM_ClearFlag(TIM6, TIM_FLAG_Update);
// 开启计数器中断
TIM_ITConfig(TIM6, TIM_IT_Update, ENABLE);
// 设置中断组为0
NVIC_PriorityGroupConfig(NVIC_PriorityGroup_0);
// 设置中断来源
NVIC_InitStructure.NVIC_IRQChannel = TIM6_IRQn;
// 设置主优先级为 0
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 1;
// 设置抢占优先级为3
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 1;
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStructure);
return TRUE;
}
//定时器使能函数
//调用库函数使能TIM6
void vMBPortTimersEnable()
{
/* Enable the timer with the timeout passed to xMBPortTimersInit( ) */
TIM_ClearITPendingBit(TIM6, TIM_IT_Update);
TIM_ITConfig(TIM6, TIM_IT_Update, ENABLE);
TIM_SetCounter(TIM6, 0x00000000);
TIM_Cmd(TIM6, ENABLE);
}
//定时器失能函数
//调用库函数失能TIM6
void vMBPortTimersDisable()
{
/* Disable any pending timers. */
TIM_ClearITPendingBit(TIM6, TIM_IT_Update);
TIM_ITConfig(TIM6, TIM_IT_Update, DISABLE);
TIM_SetCounter(TIM6, 0x00000000);
TIM_Cmd(TIM6, DISABLE);
}
//prvvTIMERExpiredISR()函数不需要更改
//需要在定时器定时结束后调用prvvTIMERExpiredISR()
static void prvvTIMERExpiredISR(void)
{
(void)pxMBPortCBTimerExpired();
}
//TIM6定时溢出中断函数
//为了方便管理把TIM6的中断服务函数放在porttimer.c函数
//定时器溢出后清除定时标志
//再调用FreeModbus的prvvTIMERExpiredISR()
void TIM6_IRQHandler(void)
{
if (TIM_GetITStatus(TIM6, TIM_IT_Update) != RESET)
{
TIM_ClearITPendingBit(TIM6, TIM_FLAG_Update);
prvvTIMERExpiredISR();
}
}
至此porttimer.c文件移植修改完毕。
portevent.c
本工程不需要修改
mbrtu.c
在这个工程里面，串口发送中断函数使用的时串口发送完成中断，所以在mbrtu.c文件的 eMBRTUSend() 函数里面还要加上一段函数用于手动发送第一个字节。
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. */
eSndState = STATE_TX_XMIT;
/*插入以下代码完成一次发送，启动发送完成中断*/
xMBPortSerialPutByte((CHAR)*pucSndBufferCur);
pucSndBufferCur++;
usSndBufferCount--;
/*结束*/
vMBPortSerialEnable(FALSE, TRUE);
}
else
{
eStatus = MB_EIO;
}
EXIT_CRITICAL_SECTION();
return eStatus;
}
到这里FreeModbus的移植（Modbus RTU）已经基本完成。
接下来是编写main函数。
最后一步 main.c文件
main函数
因为是Modbus的测试工程，板载外设只用到了一个串口和一个定时器，这两个外设都在FreeModbus的移植文件中修改，没有在main.c中体现出来。
本工程的main函数很简单，都是调用FreeModbus的函数
int main(void)
{
eMBInit(MB_RTU, 0X01, 1, 9600, MB_PAR_NONE);//初始化FreeModbus
eMBEnable();//FreeModbus使能
while (1)
{
eMBPoll();//在while (1)循环调用eMBPoll()
}
}
定义Modbus对象
Modbus常用的数据类型有4种：
线圈量（可读可写开关量）
离散输入量（只读开关量）
保持寄存器（可读可写模拟量）
输入寄存器（只读模拟量）
根据工程的不同我们要自己定义用来存储这些数据的数组
在FreeModbus的demo里面对这四种数据类型都预留了函数接口，并编写了保持寄存器作为范例。工程参考armink的移植补充完成其他数据类型的定义。数据类型的定义可根据工程需要进行裁剪
线圈量
#define COIL_START 0
#define COIL_NCOILS 100
static USHORT usCoilStart = COIL_START;
static UCHAR usCoilBuf[COIL_NCOILS] = {0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x10};
#if S_COIL_NCOILS % 8
UCHAR ucSCoilBuf[COIL_NCOILS / 8 + 1];
#else
UCHAR ucSCoilBuf[COIL_NCOILS / 8];
#endif
/**
* Modbus slave coils callback function.
*
* @param pucRegBuffer coils buffer
* @param usAddress coils address
* @param usNCoils coils number
* @param eMode read or write
*
* @return result
*/
eMBErrorCode
eMBRegCoilsCB(UCHAR *pucRegBuffer, USHORT usAddress, USHORT usNCoils,
eMBRegisterMode eMode)
{
eMBErrorCode eStatus = MB_ENOERR;
USHORT iRegIndex, iRegBitIndex, iNReg;
iNReg = usNCoils / 8 + 1;
usAddress--;
if ((usAddress >= usCoilStart) && (usAddress + usNCoils <= usCoilStart + COIL_NCOILS))
{
iRegIndex = (USHORT)(usAddress - usCoilStart) / 8;
iRegBitIndex = (USHORT)(usAddress - usCoilStart) % 8;
switch (eMode)
{
/* read current coil values from the protocol stack. */
case MB_REG_READ:
while (iNReg > 0)
{
*pucRegBuffer++ = xMBUtilGetBits(&usCoilBuf[iRegIndex++], iRegBitIndex, 8);
iNReg--;
}
pucRegBuffer--;
/* last coils */
usNCoils = usNCoils % 8;
/* filling zero to high bit */
*pucRegBuffer = *pucRegBuffer << (8 - usNCoils);
*pucRegBuffer = *pucRegBuffer >> (8 - usNCoils);
break;
/* write current coil values with new values from the protocol stack. */
case MB_REG_WRITE:
while (iNReg > 1)
{
xMBUtilSetBits(&usCoilBuf[iRegIndex++], iRegBitIndex, 8, *pucRegBuffer++);
iNReg--;
}
/* last coils */
usNCoils = usNCoils % 8;
/* xMBUtilSetBits has bug when ucNBits is zero */
if (usNCoils != 0)
{
xMBUtilSetBits(&usCoilBuf[iRegIndex++], iRegBitIndex, usNCoils, *pucRegBuffer++);
}
break;
}
}
else
{
eStatus = MB_ENOREG;
}
return eStatus;
}
离散输入量
#define DISCRETE_START 0
#define DISCRETE_NDISCRETES 100
static USHORT usNDiscreteStart = DISCRETE_START;
static UCHAR usDiscreteBuf[DISCRETE_NDISCRETES] = {0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x10};
#if DISCRETE_NDISCRETES % 8
UCHAR ucSDiscInBuf[DISCRETE_NDISCRETES / 8 + 1];
#else
UCHAR ucSDiscInBuf[DISCRETE_NDISCRETES / 8];
#endif
/**
* Modbus slave discrete callback function.
*
* @param pucRegBuffer discrete buffer
* @param usAddress discrete address
* @param usNDiscrete discrete number
*
* @return result
*/
eMBErrorCode
eMBRegDiscreteCB(UCHAR *pucRegBuffer, USHORT usAddress, USHORT usNDiscrete)
{
eMBErrorCode eStatus = MB_ENOERR;
USHORT iRegIndex, iRegBitIndex, iNReg;
iNReg = usNDiscrete / 8 + 1;
usAddress--;
if ((usAddress >= usNDiscreteStart) && (usAddress + usNDiscrete <= usNDiscreteStart + DISCRETE_NDISCRETES))
{
iRegIndex = (USHORT)(usAddress - usNDiscrete) / 8;
iRegBitIndex = (USHORT)(usAddress - usNDiscrete) % 8;
while (iNReg > 0)
{
*pucRegBuffer++ = xMBUtilGetBits(&usDiscreteBuf[iRegIndex++],
iRegBitIndex, 8);
iNReg--;
}
pucRegBuffer--;
/* last discrete */
usNDiscrete = usNDiscrete % 8;
/* filling zero to high bit */
*pucRegBuffer = *pucRegBuffer << (8 - usNDiscrete);
*pucRegBuffer = *pucRegBuffer >> (8 - usNDiscrete);
}
else
{
eStatus = MB_ENOREG;
}
return eStatus;
}
保持寄存器
//保持寄存器变量
#define REG_HOLDING_START 0
#define REG_HOLDING_NREGS 100
static USHORT usRegHoldingStart = REG_HOLDING_START;
static USHORT usRegHoldingBuf[REG_HOLDING_NREGS] = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
/**
* Modbus slave holding register callback function.
*
* @param pucRegBuffer holding register buffer
* @param usAddress holding register address
* @param usNRegs holding register number
* @param eMode read or write
*
* @return result
*/
eMBErrorCode
eMBRegHoldingCB(UCHAR *pucRegBuffer, USHORT usAddress, USHORT usNRegs,
eMBRegisterMode eMode)
{
eMBErrorCode eStatus = MB_ENOERR;
USHORT iRegIndex;
/* it already plus one in modbus function method. */
usAddress--;
if ((usAddress >= usRegHoldingStart) && (usAddress + usNRegs <= usRegHoldingStart + REG_HOLDING_NREGS))
{
iRegIndex = usAddress - usRegHoldingStart;
switch (eMode)
{
/* read current register values from the protocol stack. */
case MB_REG_READ:
while (usNRegs > 0)
{
*pucRegBuffer++ = (UCHAR)(usRegHoldingBuf[iRegIndex] >> 8);
*pucRegBuffer++ = (UCHAR)(usRegHoldingBuf[iRegIndex] & 0xFF);
iRegIndex++;
usNRegs--;
}
break;
/* write current register values with new values from the protocol stack. */
case MB_REG_WRITE:
while (usNRegs > 0)
{
usRegHoldingBuf[iRegIndex] = *pucRegBuffer++ << 8;
usRegHoldingBuf[iRegIndex] |= *pucRegBuffer++;
iRegIndex++;
usNRegs--;
}
break;
}
}
else
{
eStatus = MB_ENOREG;
}
return eStatus;
}
输入寄存器
//输入寄存器变量
#define REG_INPUT_START 0
#define REG_INPUT_NREGS 100
static USHORT usRegInputStart = REG_INPUT_START;
static USHORT usRegInputBuf[REG_INPUT_NREGS] = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
/**
* Modbus slave input register callback function.
*
* @param pucRegBuffer input register buffer
* @param usAddress input register address
* @param usNRegs input register number
*
* @return result
*/
eMBErrorCode
eMBRegInputCB(UCHAR *pucRegBuffer, USHORT usAddress, USHORT usNRegs)
{
eMBErrorCode eStatus = MB_ENOERR;
int iRegIndex;
if ((usAddress >= usRegInputStart) && (usAddress + usNRegs <= usRegInputStart + REG_INPUT_NREGS)) //请求地址大于起始地址 && 地址长度小于设定长度
{
iRegIndex = (int)(usAddress - usRegInputStart);
while (usNRegs > 0)
{
*pucRegBuffer++ =
(unsigned char)(usRegInputBuf[iRegIndex] >> 8);
*pucRegBuffer++ =
(unsigned char)(usRegInputBuf[iRegIndex] & 0xFF);
iRegIndex++;
usNRegs--;
}
}
else
{
eStatus = MB_ENOREG;
}
return eStatus;
}
到这里基于FreeModbus的Modbus RTU工程已经完成移植了，接下来是测试各个功能码
测试
在电脑使用Modbus Poll模拟主站，开发板通过USB与电脑连接，功能测试正常。
查看串口的数据流