STM32的485最简单例程

485最基本的半双工通信配置

采用STM32F103ZET6串口3连接485芯片通信口，485芯片的A,B通过485转串口模块与电脑相连，完成在串口软件上输入输出功能。

串口3，配置函数： void USART3_Config(void) { GPIO_InitTypeDef GPIO_InitStructure; USART_InitTypeDef USART_InitStructure; NVIC_InitTypeDef NVIC_InitStructure; RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB | RCC_APB2Periph_AFIO, ENABLE);

RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART3, ENABLE); // USART3_TX -> PB10 , USART3_RX -> PB11 GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10; GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP; GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz; GPIO_Init(GPIOB, &GPIO_InitStructure); GPIO_InitStructure.GPIO_Pin = GPIO_Pin_11; GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING; GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz; GPIO_Init(GPIOB, &GPIO_InitStructure); USART_InitStructure.USART_BaudRate = 115200; // 1200; USART_InitStructure.USART_WordLength = USART_WordLength_8b; USART_InitStructure.USART_StopBits = USART_StopBits_1; USART_InitStructure.USART_Parity = USART_Parity_No; //USART_Parity_Even; USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;

USART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx; USART_Init(USART3, &USART_InitStructure); NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2); NVIC_InitStructure.NVIC_IRQChannel = USART3_IRQn;

NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 1; NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0; NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE; NVIC_Init(&NVIC_InitStructure); #ifdef PDU_USART3_DMA

USART_ITConfig(USART3, USART_IT_IDLE, ENABLE); #else // Enable the USART Receive interrupt: this interrupt is generated when the // USART3 receive data register is not empty //USART_ClearITPendingBit(USART3, USART_IT_TC); USART_ClearFlag(USART3,USART_FLAG_TC); USART_ITConfig(USART3, USART_IT_RXNE, ENABLE); USART_ITConfig(USART3, USART_IT_TC, ENABLE); //USART_ITConfig(USART3, USART_IT_TXE, ENABLE); USART_ClearFlag(USART3,USART_FLAG_TC); #endif USART_Cmd(USART3, ENABLE); USART_ClearFlag(USART3,USART_FLAG_TC); RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOE | RCC_APB2Periph_AFIO, ENABLE);

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_15; GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP; GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz; GPIO_Init(GPIOE, &GPIO_InitStructure); RS_485_TX_ENABLE(); }

PUTCHAR_PROTOTYPE {

/* Place your implementation of fputc here */ /* e.g. write a character to the USART */ USART_SendData(USART3, (uint8_t) ch); //USART_SendData(USART1,(uint8_t)ch);

/* Loop until the end of transmission */

//while (USART_GetFlagStatus(USART1, USART_FLAG_TC) == RESET) while (USART_GetFlagStatus(USART3, USART_FLAG_TXE) == RESET) {}

return ch; }

中断函数：

void USART3_IRQHandler(void) { if(USART_GetITStatus(USART3, USART_IT_IDLE) != RESET) { USART_ClearITPendingBit(USART3, USART_IT_IDLE); } if(USART_GetFlagStatus(USART3, USART_FLAG_RXNE)!=RESET) { USART_ClearFlag(USART3,USART_FLAG_RXNE);

TIM3_Init(1000, 7200); BLUE_ON(); if(cnt>=32) { cnt=0; } else{ data[cnt]=USART_ReceiveData(USART3); cnt++; } }

if ((USART_GetITStatus(USART3, USART_IT_TC) != RESET) || (USART_GetITStatus(USART3, USART_IT_TXE) != RESET) ){ USART_ClearITPendingBit(USART3, USART_IT_TC); USART_ClearITPendingBit(USART3, USART_IT_TXE); // USART_SendData(USART3, 0XFFFF); } }

void TIM3_IRQHandler(void) {

if (TIM_GetITStatus(TIM3, TIM_IT_Update) != RESET) { TIM_ClearITPendingBit(TIM3, TIM_IT_Update); TIM3_DeInit(); BLUE_OFF();

// printf(\ cnt=0; } }

static void NVIC_TIM3Configuration(void) {

NVIC_InitTypeDef NVIC_InitStructure;

/* Set the Vector Table base address at 0x08000000 */ //NVIC_SetVectorTable(NVIC_VectTab_FLASH, 0x0000);

/* Enable the TIM3 gloabal Interrupt */

NVIC_InitStructure.NVIC_IRQChannel = TIM3_IRQn;

NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0; NVIC_InitStructure.NVIC_IRQChannelSubPriority = 1; NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;

NVIC_Init(&NVIC_InitStructure); }

定时器：

void TIM3_Init(uint16_t tcon, uint16_t psc) {

TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;

// TIM3 clock enable

RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE); // reset timer TIM_DeInit(TIM3);

// Time base configuration // value to reload

TIM_TimeBaseStructure.TIM_Period = (tcon - 1); // pre-scaler value against system clock

TIM_TimeBaseStructure.TIM_Prescaler = (psc - 1); // scaler value against system clock

TIM_TimeBaseStructure.TIM_ClockDivision = 0; // counting mode

TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up; // init timer

TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure);

// Clear TIM3 update pending flag

TIM_ClearITPendingBit(TIM3, TIM_IT_Update);

// TIM IT enable of over-counting

TIM_ITConfig(TIM3, TIM_IT_Update, ENABLE);

// config timer's interruption function NVIC_TIM3Configuration(); // Enable TIM3 counter TIM_Cmd(TIM3, ENABLE); }

void TIM3_DeInit(void) { // Disable TIM3 counter TIM_Cmd(TIM3, DISABLE); // Reset timer TIM_DeInit(TIM3); // Disable TIM3 clock

RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, DISABLE); //tim3_stat = 0x00; }

主函数：

#ifdef __GNF__

#ifdef __GNUC__

/* With GCC/RAISONANCE, small printf (option LD Linker->Libraries->Small printf set to 'Yes') calls __io_putchar() */

#define PUTCHAR_PROTOTYPE int __io_putchar(int ch) #else

#define PUTCHAR_PROTOTYPE int fputc(int ch, FILE *f) #endif /* __GNUC__ */

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