IO模拟串口时序

IO模拟串口时序

STM32的IO模拟串口

文章目录

• 一、为什么要用STM32的普通IO口模拟串口？
• 二、参考程序
• 总结

一、为什么要用STM32的普通IO口模拟串口？

随着工程的增大，开发者们可能在一开始不能完全利用好STM32的资源，造成串口资源不足。例如：STM32F103C8T6只有3个串口，在不改动硬件资源的情况下，因此只能想到用IO口模拟串口的时序。

二、参考程序

代码如下（示例）：

IO2USART．ｃ

#include "IO2USART.h"

#define BuadRate_9600	104
u8 len = 0;	//接收计数
u8 USART_buf[11];  //接收缓冲区
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, ENABLE);	 //使能PB,PC端口时钟 
  GPIO_PinRemapConfig(GPIO_Remap_SWJ_JTAGDisable, ENABLE); 
	 //SoftWare Serial TXD
　GPIO_InitStructure.GPIO_Pin = GPIO_Pin_4;	    
  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(GPIOB, &GPIO_InitStructure);	  				
  GPIO_SetBits(GPIOB,GPIO_Pin_4); 						
	 
	 
	//SoftWare Serial RXD
	GPIO_InitStructure.GPIO_Pin = GPIO_Pin_5;
  　GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IPU;
  　GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;		
	GPIO_Init(GPIOB, &GPIO_InitStructure);	 

	GPIO_EXTILineConfig(GPIO_PortSourceGPIOB, GPIO_PinSource5);
	EXTI_InitStruct.EXTI_Line = EXTI_Line5;
	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= EXTI9_5_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 EXTI9_5_IRQHandler(void)
{
	if(EXTI_GetFlagStatus(EXTI_Line5) != RESET)
	{
		if(OI_RXD == 0) 
		{
			if(recvStat == COM_STOP_BIT)
			{
				recvStat = COM_START_BIT;
				TIM_Cmd(TIM4, ENABLE);
			}
		}
		EXTI_ClearITPendingBit(EXTI_Line5);
	}
}

总结

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