STM32用IO口模拟串口

PB12模拟TXD,PB13模拟RXD 发送时序比较单一，按时序图可很快实现。 接收比较复杂这里用定时器TM4的溢出中断和PB13的外部中断配合计算电平时间来获取串口数据。

#define BuadRate_9600	100
u8 len = 0;	//接收计数
u8 USART_buf[11];  //接收缓冲区
#define OI_TXD	PBout(12)
#define OI_RXD	PBin(13)

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 rf315_IoConfig()
{
	GPIO_InitTypeDef  GPIO_InitStructure;
	NVIC_InitTypeDef NVIC_InitStructure;
 	EXTI_InitTypeDef EXTI_InitStruct;
  RCC_APB2PeriphClockCmd(RCC_APB2Periph_AFIO|RCC_APB2Periph_GPIOB, ENABLE);	 //使能PB,PC端口时钟 
	 
	 //SoftWare Serial TXD
	GPIO_InitStructure.GPIO_Pin = GPIO_Pin_12;	    
  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(GPIOB,GPIO_Pin_12); 						
	 
	 
	//SoftWare Serial RXD
	GPIO_InitStructure.GPIO_Pin = GPIO_Pin_13;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IPU;
  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;		
	GPIO_Init(GPIOB, &GPIO_InitStructure);	 

	GPIO_EXTILineConfig(GPIO_PortSourceGPIOB, GPIO_PinSource13);
	EXTI_InitStruct.EXTI_Line = EXTI_Line13;
	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			 
}
void rf315_uart4Init()
{
	rf315_IoConfig();
	TIM4_Int_Init(107, 71);	 //1M计数频率
}

void rf315_SendChar(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 rf315_SendData(u8 *buf, u8 len)
{
	u8 t;
	for(t = 0; t < len; t++)
	{
		rf315_SendChar(buf[t]);
	}
}


void EXTI15_10_IRQHandler(void)
{
	if(EXTI_GetFlagStatus(EXTI_Line13) != RESET)
	{
		if(OI_RXD == 0) 
		{
			if(recvStat == COM_STOP_BIT)
			{
				recvStat = COM_START_BIT;
				TIM_Cmd(TIM4, ENABLE);
			}
		}
		EXTI_ClearITPendingBit(EXTI_Line13);
	}
}

u8 rf315_data_need_handler=0;

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;	
			/*数据协议尾*/
			if(USART_buf[len-1]==RF315_PROTOCOL_TAIL)
				rf315_data_need_handler=1;
			return;
		}
		if(OI_RXD)
		{
			recvData |= (1 << (recvStat - 1));
		}else{
			recvData &= ~(1 << (recvStat - 1));
		}	
  }		
}