STM32F030模拟串口

由于项目需要用到很多串口，而STM32F030的串口资源较少，所以需要自己写模拟串口，下面是过程。

首先进行初始化：

#define Auart1RxEXTIPort   EXTI_PortSourceGPIOA

#define Auart1RxEXTIPin   EXTI_PinSource5

#define Auart1RxLineEXTI_Line5

#define Auart1RCC   RCC_AHBPeriph_GPIOA

#define Auart1Port GPIOA

#define Auart1TxPin GPIO_Pin_6

#define Auart1RxPin GPIO_Pin_5

#define Auart1TxLow GPIO_ResetBits(Auart1Port,Auart1TxPin);

#define Auart1TxHigh GPIO_SetBits(Auart1Port,Auart1TxPin);

void Ausart1_init(void)

{

   GPIO_InitTypeDef GPIO_InitStructure;

   EXTI_InitTypeDef EXTI_InitStruct;

  NVIC_InitTypeDef NVIC_InitStructure;

  RCC->AHBENR |= Auart1RCC;

  //TX

  GPIO_InitStructure.GPIO_Pin = Auart1TxPin;//

  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;

  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_OUT;

  GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;

  GPIO_Init(Auart1Port, &GPIO_InitStructure);

  //RX

  GPIO_InitStructure.GPIO_Pin = Auart1RxPin;//

  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;

  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN;

  GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP; // 上拉输入

  GPIO_Init(Auart1Port, &GPIO_InitStructure);

  RCC->APB2ENR |=RCC_APB2Periph_SYSCFG;

  SYSCFG_EXTILineConfig(Auart1RxEXTIPort, Auart1RxEXTIPin);

  EXTI_InitStruct.EXTI_Line = Auart1RxLine;

  EXTI_InitStruct.EXTI_Mode = EXTI_Mode_Interrupt;

  EXTI_InitStruct.EXTI_Trigger = EXTI_Trigger_Falling; //下降沿中断

  EXTI_InitStruct.EXTI_LineCmd = ENABLE;

  EXTI_Init(&EXTI_InitStruct); 

  NVIC_InitStructure.NVIC_IRQChannel = EXTI4_15_IRQn;

  NVIC_InitStructure.NVIC_IRQChannelPriority = 0x01;      //优先级设置比串口1优先    级低，不然会打断串口1接收，导致数据丢失

  NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;

  NVIC_Init(&NVIC_InitStructure);

}

初始化了IO口，包括外部中断和NVIC

然后 写发送函数

void AnalogUart1SendOneByte(uint8_t datatoSend)

{

uint8_t i, tmp;

Auart1TxLow;

Tim14DelayUs(SendingDelay);

for(i = 0; i < 8; i++)

{

tmp= (datatoSend >> i) & 0x01;

if(tmp == 0)

{

Auart1TxLow;

Tim14DelayUs(SendingDelay);//0

}

else

{

Auart1TxHigh;

Tim14DelayUs(SendingDelay);//1

}

}

Auart1TxHigh;

Tim14DelayUs(SendingDelay);

}

其中 Tim14DelayUs()是自己用定时器14做的一个us延时，

TIM14初始化为：

void TIM14_Configuration(void)

{

TIM_TimeBaseInitTypeDef  TIM14_TimeBaseStructure;

RCC->APB1ENR |= RCC_APB1Periph_TIM14;

  TIM14_TimeBaseStructure.TIM_Period = 65535 - 1;   

  TIM14_TimeBaseStructure.TIM_Prescaler = 48 - 1;

 TIM14_TimeBaseStructure.TIM_ClockDivision = 0;

  TIM14_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;

  TIM_TimeBaseInit(TIM14, &TIM14_TimeBaseStructure);

TIM_Cmd(TIM14,ENABLE);    

}

Tim14DelayUs()函数为

void Tim14DelayUs(__IO uint32_t nTime)

{ 

uint16_t tmp;

tmp = TIM_GetCounter(TIM14);  

if(tmp + nTime <= 65535)

while( (TIM_GetCounter(TIM14) - tmp) < nTime );

else

{

TIM_SetCounter(TIM14, 0);

while( TIM_GetCounter(TIM14) < nTime );

}

}

然后关于参数SendingDelay，是用来控制波特率的参数

计算方法如下

#define BaudRate  9600

#define SendingDelay  (1000000/BaudRate)   

然后下面函数为发送字符串函数

void AnalogUart1SendString(uint8_t *sData,uint8_t len)

{

  uint8_t i=0;

  for(i=0;i

  {

    AnalogUart1SendOneByte(sData[i]);

  }

}

然后到最重要的中断服务函数，由于我们采用的是模拟串口，所以我们初始化时将模拟串口的输入IO口配置为中断输入，当有数据过来是，数据下拉串口输入IO，然后出发中断服务函数。下面是中断服务函数

void EXTI4_15_IRQHandler(void)

{

uint8_t i=9;

static uint8_t temp;

  if(EXTI_GetITStatus(Auart1RxLine) != RESET)

  {

    NVIC->ICER[0]= (uint32_t)0x01 << (EXTI4_15_IRQn);//对NVIC_ICER[1]的第7位赋值1

Tim14DelayUs(30);

while(i--)

  {

  temp >>=1;

if(GPIO_ReadInputDataBit(Auart1Port, Auart1RxPin)) temp |=0x80;

Tim14DelayUs(SendingDelay);

  }

if(AUsart1Typedef.RxEn==RX_EN)

{

AUsart1Typedef.RxBuf[AUsart1Typedef.RxBufCount++] = temp; 

AUsart1Typedef.RxDelayCount  =  0;

AUsart1Typedef.RxNewDataFlag =1; 

temp=0;

}

NVIC->ISER[0] = (uint32_t)0x01 << (EXTI4_15_IRQn);

    EXTI_ClearITPendingBit(Auart1RxLine);

  }

}

标红部分为接受部分，根据自己的需要填入自己的接受数组中就好了。