20年吉林省综合测评

由于当时不让带手机，这里凭借深刻的记忆来描述一下题目要求：

设计一个波形发生器，产生200-1600Hz连续可调的方波
设计一个二分频器，对1生成的信号进行二分频
根据波形发生器的频率实现以200Hz为单位依次点亮八个LED灯。

实际条件：一片CD4011，一块洞洞板，一片stm32f103zet6最小系统，八个LED，电阻电容导线焊锡等

软件部分

使用cube MX + Keil5快速建立程序框架，首先打开程序新建工程，详细流程请参考我之前的博客：
https://editor.csdn.net/md/?articleId=108711636

硬件队友焊接时，我们写测频程序，在硬件没有焊出前需要把程序按照理想情况调试好（理想情况指波形是稳定的方波，上升沿下降沿没有剧烈的抖动，频率稳定，电压合适），下面直接贴出我调试好的程序。
使用定时器2测量两个上升沿之间的实际时间，倒数即为频率，然后把得到的频率传到一个封装好的函数，题目要求频率误差在10%以内，判断是否在范围内，然后按字输出对应的管脚点亮LED。

/* USER CODE BEGIN Header */
/********************************************************************************* @file           : main.c* @brief          : Main program body******************************************************************************* @attention** <h2><center>&copy; Copyright (c) 2020 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 "tim.h"
#include "usart.h"
#include "gpio.h"/* Private includes ----------------------------------------------------------*/
/* USER CODE BEGIN Includes */
#include <stdio.h>
/* USER CODE END Includes *//* Private typedef -----------------------------------------------------------*/
/* USER CODE BEGIN PTD */
#ifdef __GNUC_
#define PUTCHAR_PROTOTYPE int __io_putchar(int ch)
#else
#define PUTCHAR_PROTOTYPE int fputc(int ch, FILE *f)
#endif
PUTCHAR_PROTOTYPE
{HAL_UART_Transmit(&huart1, (uint8_t *)&ch, 1, 0xFFFF);return ch;
}
/* USER CODE END PTD *//* Private define ------------------------------------------------------------*/
/* USER CODE BEGIN PD */
/* USER CODE END PD *//* Private macro -------------------------------------------------------------*/
/* USER CODE BEGIN PM */
uint8_t ledduan[8]={0x01, 0x03, 0x07, 0x0F, 0x1F, 0x3F, 0x7F, 0xFF};               //0~8 LED 共阳极
/* USER CODE END PM *//* Private variables ---------------------------------------------------------*//* USER CODE BEGIN PV */
uint32_t capture[2];
uint16_t V,F;
/* 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 */
void light(uint16_t L)
{if(L>190&&L<210)                 {       GPIO_Write(GPIOC,(uint16_t)(~ledduan[0]));      return;}    else if (L>390&&L<410)        {       GPIO_Write(GPIOC,(uint16_t)(~ledduan[1]));      return; }else if (L>590&&L<605)       {       GPIO_Write(GPIOC,(uint16_t)(~ledduan[2]));      return; }else if (L>790&&L<805)       {       GPIO_Write(GPIOC,(uint16_t)(~ledduan[3]));      return; }else if (L>990&&L<1010)      {       GPIO_Write(GPIOC,(uint16_t)(~ledduan[4]));      return;}else if (L>1190&&L<1210)  {       GPIO_Write(GPIOC,(uint16_t)(~ledduan[5]));      return;}else if (L>1390&&L<1410)  {       GPIO_Write(GPIOC,(uint16_t)(~ledduan[6]));      return;}else if (L>1590&&L<1610)  {       GPIO_Write(GPIOC,(uint16_t)(~ledduan[7]));      return;}
}
/* 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_TIM2_Init();MX_USART1_UART_Init();/* USER CODE BEGIN 2 */HAL_TIM_IC_Start_IT(&htim2, TIM_CHANNEL_2);/* USER CODE END 2 *//* Infinite loop *//* USER CODE BEGIN WHILE */while (1){/* USER CODE END WHILE *//* USER CODE BEGIN 3 */printf("F: %2d\r\n",F*2);HAL_Delay(100);light(F*2);}/* USER CODE END 3 */
}/*** @brief System Clock Configuration* @retval None*/
void SystemClock_Config(void)
{RCC_OscInitTypeDef RCC_OscInitStruct = {0};RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};/** Initializes the CPU, AHB and APB busses clocks */RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI;RCC_OscInitStruct.HSIState = RCC_HSI_ON;RCC_OscInitStruct.HSICalibrationValue = RCC_HSICALIBRATION_DEFAULT;RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSI_DIV2;RCC_OscInitStruct.PLL.PLLMUL = RCC_PLL_MUL9;if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK){Error_Handler();}/** Initializes the CPU, AHB and APB busses 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_DIV2;RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_1) != HAL_OK){Error_Handler();}
}/* USER CODE BEGIN 4 */
void HAL_TIM_IC_CaptureCallback(TIM_HandleTypeDef *htim)
{UNUSED(htim);  static uint8_t i;if(htim->Instance == htim2.Instance){capture[i] = HAL_TIM_ReadCapturedValue(&htim2, TIM_CHANNEL_2);  i++;if(i==2)    { i=0;V = capture[1]-capture[0]; }F = 1000000 / V;                                        //得到实际频率}
}
/* 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 *//* 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,tex: 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****/

由于HAL库并没有字输出函数，这里参考标准库自己封装一个，ODR寄存器对应16个管脚，1高0低。

程序调试完成后，使用信号发生器产生一个100-800Hz的3-5V的方波连接到PA1脚，使用USB转TTL（核心板有集成CH340芯片不需要此步骤）对应连接到开发板，使用串口调试助手观察打印信息，验证程序测频是否准确。

硬件部分

一片CD4011，集成4个与非门，两个用来产生方波，两个用来构成分频器。具体原理图如下。

Q和Q非任取一个即可，实测也可以直接焊在一起。
以上就是全部实测可行的方案，但是焊接这玩意有点玄学，可能由于一个小问题就是不好使，如果产生方波后，波形不稳定可以在CD4011的VCC与GND间加一个103电容，如果还不行就接一个负载（加一个电阻在输出和地之间）。如果不能产生方波那就…程序产生PWM频率根据电位器电压调节，如果分频器焊不出来那就继续软件二分频，直接使用IO外部中断，中断两次翻转IO电平即可。