模拟串口实现方案

来源：互联网发布：mac可以练vf 编辑：程序博客网时间：2024/05/29 16:30

最近做了一个项目,由于需要6个串口,单片机串口串口资源不够用,就用stm32单片机模拟了几路串口，波特率9600.

1、首先，我们先了解串行通信数据格式

2、数据发送端

实现方案：模拟串口的波特率为9600，故我们延时时间为104us，根据通信数据格式起始位为低电平，停止位为高电平。

*********************************************************************************************************

* 函数名: SendOneByte

* 功能说明: 模拟串口发送一字节数据

* 形参：无

* 返回值: 无

*********************************************************************************************************

void SendOneByte(uint8_t datatoSend)

{

uint8_ti, tmp;

/*Start bit */

TXD_low();

delay_us(SendingDelay);

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

{

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

if(tmp== 0)

{

TXD_low();

delay_us(SendingDelay); //0

}

else

{

TXD_high();

delay_us(SendingDelay); //1

}

/*Stop bit */

TXD_high();

delay_us(SendingDelay);

}

3、数据接收端

实现方案：串口接收数据实现比较复杂，

1、IO口需配置成外部中断（下降沿触发）

2、外部中断触发，开启定时中断TIM1

3、TIM1函数处理：第一位检测到低电平，接收到起始位，后面8位为数据位，后再检测到高电平，一个字节接收结束。

第一步：配置外部中断和104us定时器

static void EXTI_Configuration(void)

{

EXTI_InitTypeDef EXTI_InitStructure;

NVIC_InitTypeDef NVIC_InitStructure;

/*Enable the AFIO Clock */

RCC_APB2PeriphClockCmd(RCC_APB2Periph_AFIO,ENABLE);

GPIO_EXTILineConfig(GPIO_PortSourceGPIOA, GPIO_PinSource12);

/* Configure Button EXTI line */

EXTI_InitStructure.EXTI_Line = EXTI_Line12;

EXTI_InitStructure.EXTI_Mode = EXTI_Mode_Interrupt;

EXTI_InitStructure.EXTI_Trigger = EXTI_Trigger_Falling;

EXTI_InitStructure.EXTI_LineCmd = ENABLE;

EXTI_Init(&EXTI_InitStructure);

/* Enable and set Button EXTI Interrupt to the lowest priority */

NVIC_InitStructure.NVIC_IRQChannel = EXTI15_10_IRQn;

NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0x0F;

NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0x0F;

NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;

NVIC_Init(&NVIC_InitStructure);

}

*********************************************************************************************************

* 函数名: TIM1_Configuration

* 功能说明: 配置TIM1

* 形参：无

* 返回值: 无

*********************************************************************************************************

void TIM1_Configuration(void)

{

TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;

NVIC_InitTypeDef NVIC_InitStructure;

RCC_APB2PeriphClockCmd(RCC_APB2Periph_TIM1,ENABLE);

/* Time base configuration */

TIM_TimeBaseStructure.TIM_Period =SendingDelay -1;

TIM_TimeBaseStructure.TIM_Prescaler = 72-1;

TIM_TimeBaseStructure.TIM_ClockDivision= 0;

TIM_TimeBaseStructure.TIM_CounterMode =TIM_CounterMode_Up;

TIM_TimeBaseInit(TIM1,&TIM_TimeBaseStructure);

TIM_ClearITPendingBit(TIM1,TIM_FLAG_Update);

/*开启TIM1的中断 */

TIM_ITConfig(TIM1,TIM_IT_Update,ENABLE);

/* 选择TIM2的中断通道 */

NVIC_InitStructure.NVIC_IRQChannel = TIM1_UP_IRQn;

/*抢占式中断优先级设置为0 */

NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;

/*响应式中断优先级设置为0 */

NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;

/*使能中断 */

NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;

NVIC_Init(&NVIC_InitStructure);

}

第二步：外部中断触发：

void EXTI15_10_IRQHandler(void)

{

if(EXTI_GetFlagStatus(EXTI_Line12)!= RESET)

{

/*Disable the Selected IRQ Channels -------------------------------------*/

EXTI->IMR &= ~1<<12; //屏蔽外部中断

if(Rx1Flag== 0)

{

Rx1Flag= 1;

}

TIM_Cmd(TIM1,DISABLE); //开启TIM1

TIM_SetCounter(TIM1,0);

TIM_Cmd(TIM1,ENABLE); //开启TIM1

}

第三步:定时器处理，接收一个字节数据

void TIM1_UP_IRQHandler(void)

{

staticuint8_t tmp;

staticuint8_t i,j;

if(TIM_GetFlagStatus(TIM1,TIM_FLAG_Update) != RESET)

{

if(Rx1Flag == 1)

{

Rx1Flag= 2;

i=0;

}

elseif(Rx1Flag == 2)

{

tmp= GPIO_ReadInputDataBit(GPIOA, GPIO_Pin_12);

if(tmp== 1)

dataReceived[receivedNum]|= (1 << i);

else dataReceived[receivedNum] &= ~(1 << i);

i++;

}

if(i>= 8)

{

Rx1Flag= 0;

i= 0;

receivedNum++;

EXTI->IMR |= 1<<12; //屏蔽外部中断

TIM_Cmd(TIM1,DISABLE); //关闭TIM1

}

TIM_ClearITPendingBit(TIM1,TIM_FLAG_Update);

}

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