运行主程序时如何在STM32f103xx上正确实现UART1中断？

Posted 2023-02-19

【中文标题】运行主程序时如何在STM32f103xx上正确实现UART1中断？

【英文标题】：How to implement UART1 Interrupts correctly on STM32f103xx while running a main programme?

【发布时间】：2021-03-18 13:43:23

【问题描述】：

我正在尝试对我的 bluePill 进行编程以使 PB11 引脚上的 LED 闪烁，同时回应通过串行端口 UART1 发送的内容。

据我所知，中断允许我们运行我们想要的程序，并且在运行它时，如果任何标志触发了中断信号，则程序控制将被转移到在原始程序运行时运行中断服务例程，我我在这里更正吗？

所以，我试图保持绿色 LED 闪烁，当我在串行端口上键入任何内容时，红色 LED 闪烁，而绿色闪烁，并且蓝色 LED 必须始终打开，除非正在发送数据。

问题 1： 绿色 LED 从不闪烁！

问题 2： 每当通过 Arduino 串行监视器发送字母或数字时，收到的回声始终是整个发送字母中的 2 个字母，而且回声始终在同一行，我的意思是不在换行符上 所以输入 Hello 并按 Enter 会产生 He 而当输入 hi there 并按 Enter 时，它只会添加前两个字母，例如 Hehi ，为什么？

我的代码是

/* ********************** Project Description ***********************
    STM32f103xx BluePill Board
    PB10 = Green LED
    PB11 = Blue LED (To be toggled)
    PB0 = Red LED (PWM OUTPUT Controlling the Brightness)
    PB9 = Push Button for toggling the state of the blue LED
    PA0 = Potentiomater Pin (Analog Input)
    USART1 Activated and Sends the Voltage of PA0 to the user1



*/


#include "stm32f1xx.h"  // Include the MCU header
#include <stdbool.h>    // Boolean Library header
#include <stdint.h>


// Prototypes:
void UART1_Init(void);              //Enable UART1 on PA9(Tx) & PA10(Rx).
void portsEnable(void);             //Enable Clock for desired MCU Ports.
void delay(uint32_t delay);         //Intuduce Delays.
void pinsConfig(void);              //Configure the used pins.


// Defines and Macros



int main(void)

  // Inintialization:
  portsEnable();
  pinsConfig();
  UART1_Init(); // Enable USART1 & interrupts @ 8Mhz clock Speed only @ 9600Bps

  while(1)
  
    // ********  Blink The green LED ***********************
    GPIOB->BSRR = GPIO_BSRR_BS11;
    delay(100000);
    GPIOB->BSRR = GPIO_BSRR_BR11;
    delay(100000);

   // End of while loop
 // End main() loop

// ************** Function Implimentation *****************************
void UART1_Init(void)                         // Initiallize USART1

  // Reset Setting (8bit, one stop bit, no parity)
  // Enable clock for UART1 First after already enabling the PortA clock
  RCC->APB2ENR |= RCC_APB2ENR_USART1EN;       // Enable Clock to the USART1 Module

  // Pin Configuration for the USART1 Peripheral where Tx(PA9) = AF Push-Pull and Rx = Input Floating
  
  // Setting Tx (PA9) Pin
  GPIOA->CRH |= ((1<<4) | (1<<5));      // Set PA9 to Output 50Mhz Mode
  GPIOA->CRH &= ~(1<<6);                // Configure it to be an AF push-pull
  GPIOA->CRH |= (1<<7);                 // Same as above^
  
  // Setting Rx (PA10) pin
  // Nothing to be set as the reset value makes it an input pin with floating configuration
  
  // Set the Baud-Rate
  USART1->BRR = 0x341;    //@ 8Mhz, USARTDIV = 8Mhz/(16*9600) = 52.083 -> 52=0x34 and 0.083 * 16 = 1.328 = 1 which is 0x1  

  // Enable Interrupts for the USART1 Module:
  // A peripheral can generates a flag at a certain event, this flag can trigger an interrupt signal but first the certain event interrupt must be enabled and the peripheral interrupt as well and the global interrupts.
  USART1->CR1 |= USART_CR1_TXEIE | USART_CR1_RXNEIE;    // Enable the Transmit Data Register Empty Interrupt register and data received interrupt

  // Enable the Tx, Rx, USART1 as a whole block
  USART1->CR1 |= (USART_CR1_RE | USART_CR1_TE | USART_CR1_UE);

  // Enable the USART1 Global interrupt on NVIC "Nested Vectored Interrupt controller" side. The NVIC is the interrupt processing unit in the MCU.
  NVIC_EnableIRQ(USART1_IRQn);  // This function's name can't be changed!

// This is a global interrupt service routine, any flag from the USART1 will lead to the same ISR, to distinguesh which is which we check the the flags and if one is set then this what caused the interrupt
void USART1_IRQHandler(void)                  // This function's name must be the same as it's defined in the main libraries

    // Check if we are here because we Received Data or simply the "RXNE flag is set".
    if(USART1->SR & USART_SR_RXNE)  // If Rx is Not Empty, or if we received Data, The USART1->SR register is going to change as it is controlled by the hardwart and we compare it to the value of the register USART_SR_RXNE which indicates a 1 at bit5
    
      char temp = USART1->DR;  // Read the 8bit data received fron the data register into a char called temp
      USART1->DR = temp;       // Put the same data in the data register to be resent again, here the data registers are clled shadow registers they are not the same registers from the hardware prospective but from programming prospective we use the same registers
      
      while(!(USART1->SR & USART_SR_TC))
      
        // Wait while the transmission completes and indicate the waiting process by flashing the RED led indicating data being sent.
        GPIOB->BSRR = GPIO_BSRR_BR10;      // When not ready to accept more data (e.g. while transmitting data process) turn of the Blue LED
        GPIOB->BSRR = GPIO_BSRR_BS1;
        delay(10000);
        GPIOB->BSRR = GPIO_BSRR_BR1;
      

     

      // Check if we are here because the TXEIE is set "OR the Transmit complete" meaning we are ready to accept more data to transmit
      if(USART1->SR & USART_SR_TXE)
      
        // Handle transmit complete here: (Blink an LED)
        GPIOB->BSRR = GPIO_BSRR_BS10;       // When Ready to accept more data
      
      else
      
        GPIOB->BSRR = GPIO_BSRR_BR10;      // When not ready to accept more data (e.g. while transmitting data process) 
      
      
    


void portsEnable(void)                        /* Enable PortA and PortB */

  // Enable clock for Ports (A & B) on "APB2" Bus.
  RCC->APB2ENR |= RCC_APB2ENR_IOPAEN;       // Enable PortA Clock
  RCC->APB2ENR |= RCC_APB2ENR_IOPBEN;       // Enable PortB Clock


void pinsConfig(void)                         //Configure the used pins.
  
  //Set pin "PB1" as output push-pull (Red LED)
  GPIOB->CRL |= ((1<<4) | (1<<5));          //Set Pin to Output 50Mhz max speed
  GPIOB->CRL &= ~((1<<6) | (1<<7));         //Configure Pin as Push-Pull


  //Set Pin "PB9" as Input Pulled-Up (Push Button Pin)
  GPIOB->CRH &= ~(1<<6);                   //Set PB9 to input "pullup|pulldown"
  GPIOB->CRH |= (1<<7);
  GPIOB->ODR |= (1<<9);                    //Set PB9 input pin as Pull-up pin.


  //Set pin "PB10" as output push-pull (Blue LED)
  GPIOB->CRH |= ((1<<9) | (1<<8));          //Set Pin to Output 50Mhz max speed
  GPIOB->CRH &= ~((1<<11) | (1<<10));       //Configure Pin as Push-Pull

  //Set pin "PB11" as output push-pull (Green LED)
  GPIOB->CRH |= ((1<<12) | (1<<13));        //Set Pin to Output 50Mhz max speed
  GPIOB->CRH &= ~((1<<14) | (1<<15));       //Configure Pin as Push-Pull


  //Set pin PA0 as Analog input
  GPIOA->CRL &= ~((1<<0) | (1<<1));          // Make sure the Mode registers are 00 for input
  GPIOA->CRL &= ~((1<<2) | (1<<3));          // Set the CNF registers to 00 for input analog
  
 // End PinsConfig()

void delay(uint32_t delay)                    /* Psudo-delay in Milliseconds */

    for(uint32_t i = 0; i <= delay; i++)
    
      // Looping to delay!
    

【问题讨论】：

不要使用“神奇”数字

【参考方案1】：

也许下面的链接对你有帮助： stm32 dead lock