基于STM32模拟UART串口通信

#define  VCOM_BOUND     115200#define  VCOM_PIN       GPIO_Pin_11#define  VCOM_PORT      GPIOA#define  VCOM_PIN_HIGH  VCOM_PORT->BSRR = VCOM_PIN#define  VCOM_PIN_LOW   VCOM_PORT->BRR  = VCOM_PIN
#define  BSP_REG_DEM_CR                           (*(volatile unsigned int *)0xE000EDFC) //DEMCR寄存器#define  BSP_REG_DWT_CR                           (*(volatile unsigned int *)0xE0001000)   //DWT控制寄存器#define  BSP_REG_DWT_CYCCNT                       (*(volatile unsigned int *)0xE0001004) //DWT时钟计数寄存器 #define  BSP_REG_DBGMCU_CR                        (*(volatile unsigned int *)0xE0042004)
#define  DEF_BIT_00                               0x01u#define  DEF_BIT_24                               0x01000000u#define  BSP_BIT_DEM_CR_TRCENA                    DEF_BIT_24   #define  BSP_BIT_DWT_CR_CYCCNTENA                 DEF_BIT_00static unsigned int  sys_clock = 48000000;
inline void dwt_start(void){ BSP_REG_DEM_CR     |= (unsigned int)BSP_BIT_DEM_CR_TRCENA;    BSP_REG_DWT_CYCCNT  = (unsigned int)0u;            //初始化CYCCNT寄存器    BSP_REG_DWT_CR     |= (unsigned int)BSP_BIT_DWT_CR_CYCCNTENA;    //开启CYCCNT }
inline void dwt_stop(void){ BSP_REG_DWT_CR = 0;}
void vcom_pin_init(void){     GPIO_InitTypeDef GPIO_InitStructure;    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA,ENABLE);    GPIO_InitStructure.GPIO_Pin   = VCOM_PIN;    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_2MHz;    GPIO_InitStructure.GPIO_Mode  = GPIO_Mode_Out_PP;    GPIO_Init(VCOM_PORT, &GPIO_InitStructure);    GPIO_SetBits(VCOM_PORT,VCOM_PIN); VCOM_PIN_HIGH;}
void vcom_put_char(char ch){ int i; int dat[8]; uint32_t sys_clk, bit_width; volatile uint32_t time_stamp;     sys_clk = sys_clock/1000000;      bit_width = 1000000*sys_clk/VCOM_BOUND;    for(i=0; i<8; i++)               {        if(ch & 0x01)            dat[i] = 1;        else            dat[i] = 0;         ch >>= 1;    }    OS_CPU_SR cpu_sr;    enter_critical();//以下代码进行临界保护,防止被中断打断造成发送误码    dwt_start();    VCOM_PIN_LOW; //发送起始位 time_stamp = BSP_REG_DWT_CYCCNT; while(BSP_REG_DWT_CYCCNT < (time_stamp+bit_width))； for(i=0; i<8; i++) {  if(dat[i])   VCOM_PIN_HIGH;  else   VCOM_PIN_LOW;  time_stamp = BSP_REG_DWT_CYCCNT;  while(BSP_REG_DWT_CYCCNT < (time_stamp+bit_width)); //发8bit 数据位 } VCOM_PIN_HIGH; time_stamp = BSP_REG_DWT_CYCCNT; while(BSP_REG_DWT_CYCCNT < (time_stamp+bit_width));     //发停止位 dwt_stop(); exit_critical();}
void vcom_printf(const char *fmt, ...){    char buf[0x80];    int  i;    va_list ap; memset(buf, 0x00, sizeof(buf));    va_start(ap, fmt);    vsnprintf(buf, sizeof(buf), fmt, ap);     va_end(ap);   i = 0; while(buf[i]) {  vcom_put_char(buf[i]);  i++; }}

/***软件串口的实现(IO模拟串口)* 波特率：9600    1-8-N* TXD : PC13* RXD : PB14* 使用外部中断对RXD的下降沿进行触发，使用定时器4按照9600波特率进行定时数据接收。* Demo功能: 接收11个数据，然后把接收到的数据发送出去*/

#define OI_TXD PCout(13)#define OI_RXD PBin(14)
#define BuadRate_9600 100
u8 len = 0; //接收计数u8 USART_buf[11];  //接收缓冲区
enum{ COM_START_BIT, COM_D0_BIT, COM_D1_BIT, COM_D2_BIT, COM_D3_BIT, COM_D4_BIT, COM_D5_BIT, COM_D6_BIT, COM_D7_BIT, COM_STOP_BIT,};
u8 recvStat = COM_STOP_BIT;u8 recvData = 0;
void IO_TXD(u8 Data){ u8 i = 0; OI_TXD = 0;   delay_us(BuadRate_9600); for(i = 0; i < 8; i++) {  if(Data&0x01)   OI_TXD = 1;    else   OI_TXD = 0;      delay_us(BuadRate_9600);  Data = Data>>1; } OI_TXD = 1; delay_us(BuadRate_9600);} void USART_Send(u8 *buf, u8 len){ u8 t; for(t = 0; t < len; t++) {  IO_TXD(buf[t]); }}  void IOConfig(void) { GPIO_InitTypeDef  GPIO_InitStructure; NVIC_InitTypeDef NVIC_InitStructure; EXTI_InitTypeDef EXTI_InitStruct; RCC_APB2PeriphClockCmd(RCC_APB2Periph_AFIO|RCC_APB2Periph_GPIOB|RCC_APB2Periph_GPIOC, ENABLE);  //使能PB,PC端口时钟   //SoftWare Serial TXD GPIO_InitStructure.GPIO_Pin = GPIO_Pin_13;      GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;    //推挽输出 GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;   //IO口速度为50MHz   GPIO_Init(GPIOC, &GPIO_InitStructure);        GPIO_SetBits(GPIOC,GPIO_Pin_13);            //SoftWare Serial RXD GPIO_InitStructure.GPIO_Pin = GPIO_Pin_14; GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IPU; GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;   GPIO_Init(GPIOB, &GPIO_InitStructure);    GPIO_EXTILineConfig(GPIO_PortSourceGPIOB, GPIO_PinSource14); EXTI_InitStruct.EXTI_Line = EXTI_Line14; EXTI_InitStruct.EXTI_Mode=EXTI_Mode_Interrupt; EXTI_InitStruct.EXTI_Trigger=EXTI_Trigger_Falling; //下降沿触发中断 EXTI_InitStruct.EXTI_LineCmd=ENABLE; EXTI_Init(&EXTI_InitStruct);
 NVIC_InitStructure.NVIC_IRQChannel= EXTI15_10_IRQn ;  NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority=2;  NVIC_InitStructure.NVIC_IRQChannelSubPriority =2;   NVIC_InitStructure.NVIC_IRQChannelCmd=ENABLE;   NVIC_Init(&NVIC_InitStructure);   } void TIM4_Int_Init(u16 arr,u16 psc){ TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure; NVIC_InitTypeDef NVIC_InitStructure;  RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM4, ENABLE); //时钟使能  //定时器TIM4初始化 TIM_TimeBaseStructure.TIM_Period = arr; //设置在下一个更新事件装入活动的自动重装载寄存器周期的值  TIM_TimeBaseStructure.TIM_Prescaler =psc; //设置用来作为TIMx时钟频率除数的预分频值 TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1; //设置时钟分割:TDTS = Tck_tim TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;  //TIM向上计数模式 TIM_TimeBaseInit(TIM4, &TIM_TimeBaseStructure); //根据指定的参数初始化TIMx的时间基数单位 TIM_ClearITPendingBit(TIM4, TIM_FLAG_Update); TIM_ITConfig(TIM4,TIM_IT_Update,ENABLE ); //使能指定的TIM3中断,允许更新中断  //中断优先级NVIC设置 NVIC_InitStructure.NVIC_IRQChannel = TIM4_IRQn;  //TIM4中断 NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 1;  //先占优先级1级 NVIC_InitStructure.NVIC_IRQChannelSubPriority = 1;  //从优先级1级 NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE; //IRQ通道被使能 NVIC_Init(&NVIC_InitStructure);  //初始化NVIC寄存器    }   int main(void) {   NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2);//设置中断优先级分组为组2：2位抢占优先级，2位响应优先级 delay_init(); IOConfig(); TIM4_Int_Init(107, 71);  //1M计数频率  while(1) {  if(len > 10)  {   len = 0;   USART_Send(USART_buf,11);  } }}
void EXTI15_10_IRQHandler(void){ if(EXTI_GetFlagStatus(EXTI_Line14) != RESET) {  if(OI_RXD == 0)   {   if(recvStat == COM_STOP_BIT)   {    recvStat = COM_START_BIT;    TIM_Cmd(TIM4, ENABLE);   }  }  EXTI_ClearITPendingBit(EXTI_Line14); }}
void TIM4_IRQHandler(void){   if(TIM_GetFlagStatus(TIM4, TIM_FLAG_Update) != RESET) {  TIM_ClearITPendingBit(TIM4, TIM_FLAG_Update);   recvStat++;  if(recvStat == COM_STOP_BIT)  {   TIM_Cmd(TIM4, DISABLE);   USART_buf[len++] = recvData;    return;  }  if(OI_RXD)  {   recvData |= (1 << (recvStat - 1));  }else{   recvData &= ~(1 << (recvStat - 1));  }  }  }