portserial.c文件：
#include "port.h"
/* ----------------------- Modbus includes ----------------------------------*/
#include "mb.h"
#include "mbport.h"
#include "rs485.h"
/* ----------------------- static functions ---------------------------------*/
static void prvvUARTTxReadyISR( void );
static void prvvUARTRxISR( void );
/* ----------------------- Start implementation -----------------------------*/
/**
* @brief 控制接收和发送状态
* @param xRxEnable 接收使能、
* xTxEnable 发送使能
* @retval None
*/
void
vMBPortSerialEnable( BOOL xRxEnable, BOOL xTxEnable )
{

if(xRxEnable)
{
USART_ClearITPendingBit(USART2, USART_IT_RXNE);
//使能接收和接收中断
USART_ITConfig(USART2, USART_IT_RXNE, ENABLE);
//MAX485操作 低电平为接收模式
GPIO_ResetBits(GPIOD,GPIO_Pin_2);
}
else
{
USART_ITConfig(USART2, USART_IT_RXNE, DISABLE);
//MAX485操作 高电平为发送模式
GPIO_SetBits(GPIOD,GPIO_Pin_2);
}

if(xTxEnable)
{
//使能发送完成中断
USART_ITConfig(USART2, USART_IT_TC, ENABLE);
        GPIO_SetBits(GPIOD,GPIO_Pin_2);
//prvvUARTTxReadyISR();
}
else
{
//禁止发送完成中断
USART_ITConfig(USART2, USART_IT_TC, DISABLE);
GPIO_ResetBits(GPIOD,GPIO_Pin_2);
}

}
/**
* @brief 串口初始化
* @param ucPORT 串口号
* ulBaudRate 波特率
* ucDataBits 数据位
* eParity 校验位
* @retval None
*/
BOOL
xMBPortSerialInit( UCHAR ucPORT, ULONG ulBaudRate, UCHAR ucDataBits, eMBParity eParity )
{
(void)ucPORT; //不修改串口
(void)ucDataBits; //不修改数据位长度
(void)eParity; //不修改校验格式

GPIO_InitTypeDef GPIO_InitStructure;
USART_InitTypeDef USART_InitStructure;

//使能USART2，GPIOA
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE);//使能GPIOA,D时钟
RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART2,ENABLE);//使能USART2时钟

//GPIOA2 USART2_Tx
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_2;        //PA2
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;        //复用推挽
GPIO_Init(GPIOA, &GPIO_InitStructure);
//GPIOA.3 USART2_Rx
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_3;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING; //浮动输入
GPIO_Init(GPIOA, &GPIO_InitStructure);

USART_InitStructure.USART_BaudRate = ulBaudRate; //只修改波特率
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;
switch(eParity)
    {
    case MB_PAR_NONE:USART_InitStructure.USART_Parity = USART_Parity_No;
                USART_InitStructure.USART_WordLength = USART_WordLength_8b;
                break;
    case MB_PAR_ODD:USART_InitStructure.USART_Parity = USART_Parity_Odd;
                USART_InitStructure.USART_WordLength = USART_WordLength_9b;
                break;
    case MB_PAR_EVEN:USART_InitStructure.USART_Parity = USART_Parity_Even;
                USART_InitStructure.USART_WordLength = USART_WordLength_9b;
                break;
    default:break;
    }


//串口初始化
USART_Init(USART2, &USART_InitStructure);
//使能USART2
USART_Cmd(USART2, ENABLE);
//vMBPortSerialEnable(FALSE,FALSE);
//USART_ClearFlag(USART2,USART_FLAG_TC);
       
NVIC_InitTypeDef NVIC_InitStructure;
NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2);
//设定USART2 中断优先级
NVIC_InitStructure.NVIC_IRQChannel = USART2_IRQn;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
NVIC_InitStructure.NVIC_IRQChannelSubPriority =1;
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStructure);

//最后配置485发送和接收模式
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOD, ENABLE);
//GPIOD.2
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_2;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
GPIO_Init(GPIOD, &GPIO_InitStructure);

return TRUE;
}



/*xMBPortSerialPutByte和xMBPortSerialGetByte两个函数用于串口发送和接收数据，在这里只要调用STM32的库函数即可。*/
BOOL
xMBPortSerialPutByte( CHAR ucByte )
{
        //发送数据
USART_SendData(USART2, ucByte);
while(USART_GetFlagStatus(USART2,USART_FLAG_TC) != SET);
return TRUE;
}

BOOL
xMBPortSerialGetByte( CHAR * pucByte )
{
           //接受数据
        *pucByte = USART_ReceiveData(USART2);
    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 )
{
//mb.c eMBInit函数中
//pxMBFrameCBTransmitterEmpty = xMBRTUTransmitFSM
//发送状态机
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.
*/
/*FreeModbus协议栈通过串口中断接收一帧数据，用户需在串口接收中断中回调prvvUARTRxISR()函数；*/
static void prvvUARTRxISR( void )
{
//mb.c eMBInit函数中
//pxMBFrameCBByteReceived = xMBRTUReceiveFSM
//接收状态机
pxMBFrameCBByteReceived();
}


void USART2_IRQHandler(void)
{
//发生接收中断
if(USART_GetITStatus(USART2, USART_IT_RXNE) == SET)
{
prvvUARTRxISR();
//清除中断标志位
USART_ClearITPendingBit(USART2, USART_IT_RXNE);
}

//发生完成中断
if(USART_GetITStatus(USART2, USART_IT_TC)== SET)
{
prvvUARTTxReadyISR();
//清除中断标志
USART_ClearITPendingBit(USART2, USART_IT_TC);
}
}

void
EnterCriticalSection( void )
{
  __disable_irq();
}

void
ExitCriticalSection( void )
{
  __enable_irq();
}

porttimer.c文件/* ----------------------- Platform includes --------------------------------*/
#include "port.h"
#include "stm32f10x_tim.h"
/* ----------------------- Modbus includes ----------------------------------*/
#include "mb.h"
#include "mbport.h"

/* ----------------------- static functions ---------------------------------*/
static void prvvTIMERExpiredISR( void );
/*
初始化时钟xMBPortTimersInit()
添加打开和关闭时钟的函数void vMBPortTimersEnable(  )
以及voidvMBPortTimersDisable(  )，
还有超时中断函数voidTIM2_IRQHandler(void)。
*/
/* ----------------------- Start implementation -----------------------------*/
BOOL xMBPortTimersInit( USHORT usTim1Timerout50us )
{
  TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;
  NVIC_InitTypeDef NVIC_InitStructure;

        TIM_DeInit(TIM2); //重新将Timer3设置为缺省值
  uint16_t PrescalerValue = 0;

  //使能定时器2时钟
  RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE); //时钟使能

  //定时器时间基配置说明
  //系统时钟为72MHz，APB1经过2分频为36MHz
  //TIM2的时钟倍频后为72MHz（硬件自动倍频,达到最大）
  //TIM2的分频系数为3599，时间基频率为72 / (1 + Prescaler) = 20KHz,基准为50us
  //TIM最大计数值为usTim1Timerout50us
  PrescalerValue = (uint16_t) (SystemCoreClock / 20000) - 1;
  //定时器1初始化
  TIM_TimeBaseStructure.TIM_Period = (uint16_t) usTim1Timerout50us;
  TIM_TimeBaseStructure.TIM_Prescaler = PrescalerValue;
  TIM_TimeBaseStructure.TIM_ClockDivision = 0;
  TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
  TIM_TimeBaseInit(TIM2, &TIM_TimeBaseStructure);
  //预装载使能
  TIM_ARRPreloadConfig(TIM2, ENABLE);

  NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2);
  //定时器2中断优先级
  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);

  //清除溢出中断标志位
  TIM_ClearITPendingBit(TIM2,TIM_IT_Update);
  //定时器2溢出中断关闭
  TIM_ITConfig(TIM2, TIM_IT_Update, DISABLE);
  //定时器2禁能
  TIM_Cmd(TIM2,  DISABLE);
  return TRUE;
}


inline void
vMBPortTimersEnable(  )
{
       
  TIM_ClearITPendingBit(TIM2, TIM_IT_Update);
  TIM_ITConfig(TIM2, TIM_IT_Update, ENABLE);
  //设定定时器2的初始值
  TIM_SetCounter(TIM2,0x0000);
  //定时器2启动
  TIM_Cmd(TIM2, ENABLE);
       
  /* Enable the timer with the timeout passed to xMBPortTimersInit( ) */
}

inline void
vMBPortTimersDisable(  )
{
  TIM_ClearITPendingBit(TIM2, TIM_IT_Update);
  TIM_ITConfig(TIM2, TIM_IT_Update, DISABLE);
  TIM_SetCounter(TIM2,0x0000);
  //关闭定时器2
  TIM_Cmd(TIM2, DISABLE);
  /* Disable any pending timers. */
}

/* 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)
  {
    //清除定时器T4溢出中断标志位
    TIM_ClearITPendingBit(TIM2, TIM_IT_Update);

    prvvTIMERExpiredISR( );
  }
}

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