蓝桥杯嵌入式第十四届省赛题目解析_蓝桥杯嵌入式真题

前几天刚刚参加完第十四届的省赛，这届题目比我想象中的要难，其实想一想这也是应该的，以前的知识点都被摸透了，也是需要加入新的知识点了，但是我还是想说能不能别在我参加的时候加大题目难度啊。

不过听说隔壁单片机的省赛都比往年的国赛还难，这就有点离谱了。好了，进入正题了，老规矩先看看客观题。

客观题

收集的一些历年的比赛客观题和解析，以及程序设计题的PDF，在这里分享给大家。 

链接：https://pan.baidu.com/s/1hTw0inSbLjX57hOtankgKw 
提取码：np1p

有什么不理解的地方，可以在评论区提出来嗷。

程序设计题 

题目解析

这届题目用到的模块是LCD，LED，按键，ADC，PWM和脉冲捕获。其中新考点就是按键的长按和脉冲输入捕获。

按键长按的话，由于我是在定时器中每10ms扫描一次按键，按照题目要求长按时间是2s以上，所以设置一个变量用来计数，如果在按键松开时计数值达到200以上就是长按，否则就是短按。

脉冲捕获，其实就是使用定时器获得一个方波周期的时间，再用定时器频率 / 时间t就可以计算出引脚的输出频率了。

 如图所示，当有上升沿发生就进入中断，开始计时，当下一个上升沿来到时也进入中断，这就可以获得时间t计算出频率，然后再清除t的值，具体看代码。再多使用一个通道捕获下降沿的时间t1，就可以计算出占空比，用高电平的时间t1 / 总的时间t。感兴趣的可以试试，多准备准备，以防下次会考。说完了，那就配置CubeMX吧。

CubeMX配置

时钟配置完了，需要按下回车（Enter）来保存。 

 根据原理图配置GPIO引脚，其中lcd和led的引脚都设置为output，按键设置为input，PB15设置为ADC2的15通道，PA1设置为定时器2的第2通道，PA7设置为定时器17的通道1，需要把PD2也设置为output用来作为led的锁存器。 

 在GPIO中选中按键的引脚，设置为上拉输入模式。 

在GPIO中，选中led的引脚，设置为初始状态为高电平，推挽输出模式，既不上拉也不下拉。其他引脚使用默认设置就是行。

设置定时器3每10ms中断一次。 

 

定时器2的通道2设置为PWM通道2，然后设置预分频器值和自动重装值以及占空比。

开启定时器中断，设置通道1为上升沿的输入捕获。

勾选ADC2的第15通道，其他设置默认就行。 

设置项目名字和保存路径（建议不要有中文），以及IDE的版本。  

 

 勾选这个主要是让.c和.h文件单独分开，之后就可以生成代码了，CubeMX配置就完成了，如果之后想要添加新的模块或者修改配置好了模块的值，可以直接在文件中打开CubeMX的工程进行修改，改完后再点击GENERATE CODE就行了。

代码演示 

main.c

/* USER CODE BEGIN Header */
/**
  ******************************************************************************
  * @file           : main.c
  * @brief          : Main program body
  ******************************************************************************
  * @attention
  *
  * <h2><center>&copy; Copyright (c) 2023 STMicroelectronics.
  * All rights reserved.</center></h2>
  *
  * This software component is licensed by ST under BSD 3-Clause license,
  * the "License"; You may not use this file except in compliance with the
  * License. You may obtain a copy of the License at:
  *                        opensource.org/licenses/BSD-3-Clause
  *
  ******************************************************************************
  */
/* USER CODE END Header */
/* Includes ------------------------------------------------------------------*/
#include "main.h"
#include "adc.h"
#include "tim.h"
#include "gpio.h"
 
/* Private includes ----------------------------------------------------------*/
/* USER CODE BEGIN Includes */
#include "sys.h"
#include "show.h"
#include "lcd.h"
#include "timer.h"
/* USER CODE END Includes */
 
/* Private typedef -----------------------------------------------------------*/
/* USER CODE BEGIN PTD */
 
/* USER CODE END PTD */
 
/* Private define ------------------------------------------------------------*/
/* USER CODE BEGIN PD */
/* USER CODE END PD */
 
/* Private macro -------------------------------------------------------------*/
/* USER CODE BEGIN PM */
 
/* USER CODE END PM */
 
/* Private variables ---------------------------------------------------------*/
 
/* USER CODE BEGIN PV */
extern uint8_t btn,long_btn;  //按键短按值，和key4的长按标志
extern uint32_t f;   //是捕获计算的频率
 
bool choice = 0;   //0是参数R，1是参数K
bool fre_flag = 0; //切换高低频模式的锁，为1时不能切换
bool lock = 0;     //为1时占空比锁定
char M='L';        //L是低频模式，H是高频模式
uint8_t jm = 0;    //0是数据界面，1是参数界面，2记录界面
uint16_t P = 100;  //占空比
uint8_t N = 0;
uint8_t R = 1,K = 1;
uint8_t tempR = 1,tempK = 1;
float V = 0.0f,MH = 0.0f,ML = 0.0f;
float Volt = 0.0f;
/* USER CODE END PV */
 
/* Private function prototypes -----------------------------------------------*/
void SystemClock_Config(void);
/* USER CODE BEGIN PFP */
 
/* USER CODE END PFP */
 
/* Private user code ---------------------------------------------------------*/
/* USER CODE BEGIN 0 */
 
/* USER CODE END 0 */
 
/**
  * @brief  The application entry point.
  * @retval int
  */
int main(void)
{
  /* USER CODE BEGIN 1 */
 
  /* USER CODE END 1 */
 
  /* MCU Configuration--------------------------------------------------------*/
 
  /* Reset of all peripherals, Initializes the Flash interface and the Systick. */
  HAL_Init();
 
  /* USER CODE BEGIN Init */
 
  /* USER CODE END Init */
 
  /* Configure the system clock */
  SystemClock_Config();
 
  /* USER CODE BEGIN SysInit */
 
  /* USER CODE END SysInit */
 
  /* Initialize all configured peripherals */
  MX_GPIO_Init();
  MX_ADC2_Init();
  MX_TIM2_Init();
  MX_TIM3_Init();
  MX_TIM17_Init();
  /* USER CODE BEGIN 2 */
    LCD_Init();
	LCD_Clear(Black);
	LCD_SetBackColor(Black);
	LCD_SetTextColor(White);
	
	HAL_TIM_Base_Start_IT(&htim3);
	HAL_TIM_PWM_Start(&htim2,TIM_CHANNEL_2);
	HAL_TIM_IC_Start_IT(&htim17,TIM_CHANNEL_1);
  /* USER CODE END 2 */
 
  /* Infinite loop */
  /* USER CODE BEGIN WHILE */
  while (1)
  {
    /* USER CODE END WHILE */
 
    /* USER CODE BEGIN 3 */
		Volt = getADC(&hadc2);
		V = (f*2*R*3.14f)/(100*K);
		switch(btn)
		{
			case 1:
			{
				Key1();
				btn = 0;
			}
			break;
			
			case 2:
			{
				Key2();
				btn = 0;
			}
			break;
			
			case 3:
			{
				Key3();
				btn = 0;
			}
			break;
			
			case 4:
			{
				Key4();
				btn = 0;
			}
			break;
		}
		if(long_btn && 0 == jm)
		{
			lock = 1;
			long_btn = 0;
		}
		
		if(0==jm)
			DATA();
		else if(1==jm)
			PARA();
		else
			RECD();
		
		LED_Hint();  //处理LED
		InferDuty(); //调整占空比
		InferFre();  //计算最大最小速度值
  }
  /* USER CODE END 3 */
}
 
/**
  * @brief System Clock Configuration
  * @retval None
  */
void SystemClock_Config(void)
{
  RCC_OscInitTypeDef RCC_OscInitStruct = {0};
  RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};
  RCC_PeriphCLKInitTypeDef PeriphClkInit = {0};
 
  /** Configure the main internal regulator output voltage
  */
  HAL_PWREx_ControlVoltageScaling(PWR_REGULATOR_VOLTAGE_SCALE1);
  /** Initializes the RCC Oscillators according to the specified parameters
  * in the RCC_OscInitTypeDef structure.
  */
  RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSE;
  RCC_OscInitStruct.HSEState = RCC_HSE_ON;
  RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
  RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSE;
  RCC_OscInitStruct.PLL.PLLM = RCC_PLLM_DIV3;
  RCC_OscInitStruct.PLL.PLLN = 20;
  RCC_OscInitStruct.PLL.PLLP = RCC_PLLP_DIV2;
  RCC_OscInitStruct.PLL.PLLQ = RCC_PLLQ_DIV2;
  RCC_OscInitStruct.PLL.PLLR = RCC_PLLR_DIV2;
  if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
  {
    Error_Handler();
  }
  /** Initializes the CPU, AHB and APB buses clocks
  */
  RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK
                              |RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2;
  RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
  RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
  RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV1;
  RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;
 
  if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_2) != HAL_OK)
  {
    Error_Handler();
  }
  /** Initializes the peripherals clocks
  */
  PeriphClkInit.PeriphClockSelection = RCC_PERIPHCLK_ADC12;
  PeriphClkInit.Adc12ClockSelection = RCC_ADC12CLKSOURCE_SYSCLK;
  if (HAL_RCCEx_PeriphCLKConfig(&PeriphClkInit) != HAL_OK)
  {
    Error_Handler();
  }
}
 
/* USER CODE BEGIN 4 */
 
/* USER CODE END 4 */
 
/**
  * @brief  This function is executed in case of error occurrence.
  * @retval None
  */
void Error_Handler(void)
{
  /* USER CODE BEGIN Error_Handler_Debug */
  /* User can add his own implementation to report the HAL error return state */
  __disable_irq();
  while (1)
  {
  }
  /* USER CODE END Error_Handler_Debug */
}
 
#ifdef  USE_FULL_ASSERT
/**
  * @brief  Reports the name of the source file and the source line number
  *         where the assert_param error has occurred.
  * @param  file: pointer to the source file name
  * @param  line: assert_param error line source number
  * @retval None
  */
void assert_failed(uint8_t *file, uint32_t line)
{
  /* USER CODE BEGIN 6 */
  /* User can add his own implementation to report the file name and line number,
     ex: printf("Wrong parameters value: file %s on line %d\r\n", file, line) */
  /* USER CODE END 6 */
}
#endif /* USE_FULL_ASSERT */
 
/************************ (C) COPYRIGHT STMicroelectronics *****END OF FILE****/

main.h

/* USER CODE BEGIN Header */
/**
  ******************************************************************************
  * @file           : main.h
  * @brief          : Header for main.c file.
  *                   This file contains the common defines of the application.
  ******************************************************************************
  * @attention
  *
  * Copyright (c) 2023 STMicroelectronics.
  * All rights reserved.
  *
  * This software is licensed under terms that can be found in the LICENSE file
  * in the root directory of this software component.
  * If no LICENSE file comes with this software, it is provided AS-IS.
  *
  ******************************************************************************
  */
/* USER CODE END Header */
 
/* Define to prevent recursive inclusion -------------------------------------*/
#ifndef __MAIN_H
#define __MAIN_H
 
#ifdef __cplusplus
extern "C" {
#endif
 
/* Includes ------------------------------------------------------------------*/
#include "stm32g4xx_hal.h"
 
/* Private includes ----------------------------------------------------------*/
/* USER CODE BEGIN Includes */
#include <stdio.h>
#include <string.h>
#include <stdbool.h>
/* USER CODE END Includes */
 
/* Exported types ------------------------------------------------------------*/
/* USER CODE BEGIN ET */
 
/* USER CODE END ET */
 
/* Exported constants --------------------------------------------------------*/
/* USER CODE BEGIN EC */
 
/* USER CODE END EC */
 
/* Exported macro ------------------------------------------------------------*/
/* USER CODE BEGIN EM */
 
/* USER CODE END EM */
 
/* Exported functions prototypes ---------------------------------------------*/
void Error_Handler(void);
 
/* USER CODE BEGIN EFP */
 
/* USER CODE END EFP */
 
/* Private defines -----------------------------------------------------------*/
/* USER CODE BEGIN Private defines */
 
/* USER CODE END Private defines */
 
#ifdef __cplusplus
}
#endif
 
#endif /* __MAIN_H */

main.h中添加了几个头文件和define。

sys.c

#include "sys.h"
 
Btn key[4] = {0};
uint8_t btn = 0, long_btn = 0;
uint16_t LED = 0xff00;
 
extern uint8_t jm;
extern bool L2_flag;
extern bool fre_flag;
extern bool lock, choice;
extern uint8_t R ,K ,N;
extern uint8_t tempR ,tempK;
 
void LED_SET(void)
{
	GPIOC->ODR = (uint32_t)LED;
	HAL_GPIO_WritePin(GPIOD,GPIO_PIN_2,GPIO_PIN_SET);
	HAL_GPIO_WritePin(GPIOD,GPIO_PIN_2,GPIO_PIN_RESET);
}
 
void LED_Hint(void)
{
	if(0 == jm)
	{
		LED &= ~(0x01ff); 
		LED_SET();
	}
	else
	{
		LED |= 0x0100; 
		LED_SET();
	}
	
	if(1 == L2_flag && 1 == fre_flag)
	{
		LED &= ~(0x02ff); 
		LED_SET();
	}
	else
	{
		LED |= 0x0200; 
		LED_SET();
	}
	
	if(1 == lock)
	{
		LED &= ~(0x04ff); 
		LED_SET();
	}
	else
	{
		LED |= 0x0400; 
		LED_SET();
	}
}
 
void KEY_Scan(void)
{
	uint8_t i;
	
	key[0].press = HAL_GPIO_ReadPin(GPIOB, GPIO_PIN_0);
	key[1].press = HAL_GPIO_ReadPin(GPIOB, GPIO_PIN_1);
	key[2].press = HAL_GPIO_ReadPin(GPIOB, GPIO_PIN_2);
	key[3].press = HAL_GPIO_ReadPin(GPIOA, GPIO_PIN_0);
	
	for(i=0;i<4;i++)
	{
		switch(key[i].state)
		{
			case 0:
				if(key[i].press == 0)
					key[i].state = 1;
			break;
			
			case 1:
			{
				if(key[i].press == 0)
				{
					key[i].state = 2;
					btn = i+1;
					if(3 == i)
						key[i].long_time = 1;
				}
				else
					key[i].state = 0;
			}
			break;
			
			case 2:
			{
				if(key[i].press == 1)
				{
					key[i].state = 0;
					if(key[3].long_time>=200)
						long_btn = i+1;
					else
						key[3].long_time++;
				}
				if(3 == i)
					key[3].long_time++;
			}
			break;
		}
	}
}
 
float getADC(ADC_HandleTypeDef *pin)
{
	uint16_t adc;
	HAL_ADC_Start(pin);
	adc = HAL_ADC_GetValue(pin);
	return adc*3.3/4096;
}
 
void Key1(void)  //按键1需要完成的功能
{
	if(3 == ++jm)
		jm = 0;
	if(1 == jm)
	{
		tempR = R;
		tempK = K;
	}
	else            // 从参数界面退出时，新的 R 参数和 K 参数生效。
	{
		R = tempR;
		K = tempK;
	}
	choice = 0;
	LCD_Clear(Black);
}
 
void Key2(void)   //按键2需要完成的功能
{
	if(0 == jm && 0 == fre_flag)
	{
		fre_flag = 1;
		N++;
	}
	
	if(1 == jm)
	{
		choice ^= 1;
	}
}
 
void Key3(void)   //按键3需要完成的功能
{
	if(1 == jm)
	{
		if(0 == choice)
		{
			if(++tempR>10)
				tempR = 1;
		}
		else
		{
			if(++tempK>10)
				tempK = 1;
		}
	}
}
 
void Key4(void)   //按键4需要完成的功能
{
	if(1 == jm)
	{
		if(0 == choice)
		{
			if(--tempR<1)
				tempR = 10;
		}
		else
		{
			if(--tempK<1)
				tempK = 10;
		}
	}
	
	if(0 == jm)
		lock = 0;
}

sys.h

#ifndef __SYS_H
#define __SYS_H
 
#include "main.h"
#include "lcd.h"
 
typedef struct{
	bool press;
	uint8_t state;
	uint16_t long_time;
}Btn;
 
void LED_SET(void);
void LED_Hint(void);
void KEY_Scan(void);
float getADC(ADC_HandleTypeDef *pin);
void Key1(void);
void Key2(void);
void Key3(void);
void Key4(void);
 
#endif

led使用寄存器，目的是单独控制一个LED灯时不干扰其他LED灯，使用HAL库函数，改变一个灯的值，会干扰到其他灯的显示，有没有好心人在评论区告知一下怎么使用HAL库才不会有这种情况，感谢。  

show.c

#include "show.h"
 
char text[21] = {0};
 
extern uint8_t N,R,K;
extern uint16_t P;
extern uint16_t fre;
extern float V,MH,ML;
extern char M;
extern float Volt;
extern bool lock;
extern uint8_t tempR,tempK;
 
void LCD_SHOW(uint8_t line, char *text)
{
	LCD_DisplayStringLine(line*24, (u8 *)text);
}
 
void DATA(void)
{
	sprintf(text,"        DATA        ");
	LCD_SHOW(1,text);
	
	sprintf(text,"     M=%c             ",M);
	LCD_SHOW(3,text);
	
	sprintf(text,"     P=%d%%          ",P);
	LCD_SHOW(4,text);
	
	sprintf(text,"     V=%.1f         ",V);
	LCD_SHOW(5,text);
}
 
void PARA(void)
{
	sprintf(text,"        PARA        ");
	LCD_SHOW(1,text);
	
	sprintf(text,"     R=%d            ",tempR);
	LCD_SHOW(3,text);
	
	sprintf(text,"     K=%d            ",tempK);
	LCD_SHOW(4,text);
}
 
void RECD(void)
{
	sprintf(text,"        RECD        ");
	LCD_SHOW(1,text);
	
	sprintf(text,"     N=%d           ",N);
	LCD_SHOW(3,text);
	
	sprintf(text,"     MH=%.1f        ",MH);
	LCD_SHOW(4,text);
	
	sprintf(text,"     ML=%.1f        ",ML);
	LCD_SHOW(5,text);
}
 
void InferDuty(void)//调整占空比
{
	if(lock == 0)
	{
		if(Volt<=1.0f)
		{
			P = 10*(fre+1)/100;
			__HAL_TIM_SET_COMPARE(&htim2,TIM_CHANNEL_2,P);
		}
		else if(Volt>=3.0f)
		{
			P = 85*(fre+1)/100;
			__HAL_TIM_SET_COMPARE(&htim2,TIM_CHANNEL_2,P);
		}
		else
		{
			P = 37.5f*Volt-27.5f;
			__HAL_TIM_SET_COMPARE(&htim2,TIM_CHANNEL_2,P*(fre+1)/100);
		}
	}
}
 
void InferFre(void)//计算最大最小速度值
{
			ML = (4000*2*R*3.14f)/(100*K);
 
			MH = (8000*2*R*3.14f)/(100*K);
}
 

show.h

#ifndef __SHOW_H
#define __SHOW_H
 
#include "main.h"
#include "lcd.h"
#include "tim.h"
 
void LCD_SHOW(uint8_t line, char *text);
void DATA(void);
void PARA(void);
void RECD(void);
void InferDuty(void);
void InferFre(void);
 
#endif

timer.c

#include "timer.h"
 
uint16_t CCR1 = 0;
uint32_t fre_CNT = 0;
uint16_t fre = 999;
uint32_t f = 0;
uint8_t L2_CNT = 0;
bool L2_flag = 0;
 
extern bool fre_flag;
extern char M;
 
void HAL_TIM_PeriodElapsedCallback(TIM_HandleTypeDef *htim)
{
	if(htim->Instance == TIM3)
	{
		KEY_Scan();
		if(1 == fre_flag)   //高低频模式切换，5秒钟内保证占空比不变，频率每10ms加减一
		{                   //500次刚好完成高低频模式切换需要改变的自动重装载值
			if(++fre_CNT>500)
			{
				fre_flag = 0;
				fre_CNT = 0;
				if('L' == M)
						M = 'H';
					else 
						M = 'L';
			}
			else
			{
				if('L' == M)
				{
					fre--;
					__HAL_TIM_SET_AUTORELOAD(&htim2,fre);
				}
				else
				{
					fre++;
					__HAL_TIM_SET_AUTORELOAD(&htim2,fre);
				}
			}
			
			if(++L2_CNT>10)
			{
				L2_flag ^= 1;
				L2_CNT = 0;
			}
		}
	}
}
 
 
void HAL_TIM_IC_CaptureCallback(TIM_HandleTypeDef *htim)
{
	 /*PWM 信号上升沿时，会进入中断，IC1会捕获，对应的是周期宽度测量*/
	if(htim->Instance == TIM17)
	{
		if(htim->Channel==HAL_TIM_ACTIVE_CHANNEL_1)
		{
			CCR1 = HAL_TIM_ReadCapturedValue(htim,TIM_CHANNEL_1);
			__HAL_TIM_SetCounter(htim,0);
			f = (80000000/80)/(CCR1+1);
			HAL_TIM_IC_Start(htim,TIM_CHANNEL_1);
		}
	}	
}

timer.h

#ifndef __TIMER_H
#define __TIMER_H
 
#include "main.h"
#include "tim.h"
#include "sys.h"
 
#endif

以上就是我修改过的文件和新添加的文件。还有lcd模块，不过不需要我们自己写，官方有提供，直接复制过来就行，注意有三个文件，别只复制lcd.c和lcd.h。

好了，以上就是蓝桥杯嵌入式第十四届省赛的题目解析了，如果有什么问题和建议都欢迎在评论区提出来喔。