前言：STM32G431RBT6實現嵌入式組第十二屆題目解析+源碼，本文默認讀者具備基礎的stm32知識。文章末尾有第十二屆題目。

1.題目解析

第十二屆雖說題目長，難度集中體現在uart接收的數據處理上。

1.1 分而治之，藕斷絲連

還是那句話，將不同模塊進行封裝，通過變量進行模塊間的合作。
函數將模塊分而治之，變量使模塊間藕斷絲連。

1.2 模塊化思維導圖

下圖根據題目梳理。還是使用思維導圖。

1.3 模塊解析

1.3.1 KEY模塊

還是控制按一次處理一次。老朋友了我們就不多說了，題目限制了按鍵消抖和單次處理，所以我們要加上消抖，和第十一屆的處理一模一樣。
具體實現看源碼

1.3.2 LED模塊

ld1：有空閑車位亮，否則滅
ld2：PWM占空比20%輸出亮，輸出低電平滅
解決辦法，設置一個標志位代表ld1~ld8，改變對應位的的值，再將標志位寫入ODR寄存器中來控制led的亮滅。
具體實現看源碼

1.3.3 LCD模塊

lcd顯示兩個界面，注意首次切換的時候得清屏。
根據B1界面1和界面2切換；
狀態0：參數界面；

狀態1：費用設置界面；

具體實現看源碼

1.3.4 TIM模塊

TIM2產生1s時基。PSC：16999，ARR：9999；
TIM17通道1產生2kHzPWM。PSC：16，ARR：4999；
PSC和ARR計算公式（計算周期就是頻率的倒數）：

/* 定時開啟uart接收中斷1s */
void HAL_TIM_PeriodElapsedCallback(TIM_HandleTypeDef *htim)
{HAL_UARTEx_ReceiveToIdle_IT(&huart1, uart_rx_data, 24);
}
/* pa7pwm輸出 */
void HAL_TIM_PWM_PulseFinishedCallback(TIM_HandleTypeDef *htim)
{if(pa7_pwm_ctrl == 1) TIM17->CCR1 = 999;else TIM17->CCR1 = 0;
}

1.3.5 UART模塊

12屆題目的難度就在uart的數據處理上。
1.單片機接收來自電腦固定格式的數據，我們就需要數據限制條件來寫解析接收的數據，數據長度，停車類別，車牌格式，時間格式。
2.如果格式錯誤返回Error，else判斷是停車還是取車。
2.1 應該先判斷取車，這大家都能理解。如果是取車，計算收費，時間，返回給電腦。
2.2 如果是存車，先要判斷是否有空閑車位，如果有存車，如果沒有不做處理。
具體其他涉及函數代碼請看源碼

/* uart接收數據處理 */
void HAL_UARTEx_RxEventCallback(UART_HandleTypeDef *huart, uint16_t Size)
{if(analyze_uart_str(uart_rx_data))   //分析數據格式是否正確，錯誤傳輸Error{HAL_UART_Transmit_IT(&huart1, (uint8_t*)"Error", 7); }/*格式正確處理順序 ：判斷是否是取車（停車場已有該車）-> 是: 取車+計算收費, 否: 判斷是否有空閑車位 -> 是：停車計時，否：不做處理*/else{                                     uint8_t i = find_car_in_parking(parking_flag_temporary); if(i != 8){   //表示取車if(!strcmp(parking_flag_temporary.parking_type, "VNBR")){    //計算停車費parking_fee = caculate_parking_time(i)*V_money;parking_spaces.VNBR--;parking_spaces.IDLE++;}else if(!strcmp(parking_flag_temporary.parking_type, "CNBR")){parking_fee = caculate_parking_time(i)*C_money;parking_spaces.CNBR--;parking_spaces.IDLE++;}sprintf((char*)parking_fee_str, "%4s:%4s:%u:%.2f", parking_flag_temporary.parking_type,parking_flag_temporary.car_num, caculate_parking_time(i), parking_fee);HAL_UART_Transmit_IT(&huart1, parking_fee_str, strlen((char*)parking_fee_str));memset(&parking_flag[i], 0, sizeof(parking_flag[i]));memset(&parking_time[i], 0, sizeof(parking_time[i]));}else{        //停車          i = find_free_parking();              if(i!=8){               //有空閑車位parking_flag[i] = parking_flag_temporary;parking_time[i] = parking_time_temporary;if(!strcmp(parking_flag_temporary.parking_type, "CNBR")){parking_spaces.CNBR++;parking_spaces.IDLE--;}else if(!strcmp(parking_flag_temporary.parking_type, "VNBR")){parking_spaces.VNBR++;parking_spaces.IDLE--;}}}}
}

1.3.5.1 uart數據解析

我們可以使用指針加for單個字符判斷，也可以使用string.h庫中的字符處理函數，strcmp(), strcpy(),strncmp(), strncpy()等函數，將數據先切段，再通過各段的限制條件進行格式判斷。

/**
*   @brief 判斷uart接收到的數據格式是否正確，這里只有長度判斷、車位類型、車位號碼、時間格式的判斷，
*   還可以加時間的大小比如月份只能是1~12月。還有解析時間的時候，假如說要取車，那取車時間肯定大于停車時間……
*   @para str: uart接收數據
*   @retval 1：數據格式錯誤，0：正確
*/
uint8_t analyze_uart_str(uint8_t *str)
{if(strlen((char*)str) != 24){  //return 1;}else{uint8_t *p = str;if(*p == 'C' || *p == 'V' && !strncasecmp((char*)p+1, "NBR", 3)) {strncpy(parking_flag_temporary.parking_type, (char*)str, 4);  }else return 1;for(p = str+5;p<str+9;p++){if(*p<0 || *p>127) return 1;}strncpy(parking_flag_temporary.car_num, (char*)str+5, 4);for(p = str+10; *p!='\0';p++){if(*p<'0' || *p > '9') return 1;}strncpy(parking_flag_temporary.time, (char*)str+10, 14);sscanf(parking_flag_temporary.time,"%4hu%2hhu%2hhu%2hhu%2hhu%2hhu", &parking_time_temporary.years, &parking_time_temporary.dates, &parking_time_temporary.days,&parking_time_temporary.hours, &parking_time_temporary.minutes, &parking_time_temporary.seconds);}return 0;
}

2.源碼

我所有的實現都在main.c文件中。

/* USER CODE BEGIN Header */
/********************************************************************************* @file           : main.c* @brief          : Main program body******************************************************************************* @attention** Copyright (c) 2025 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 */
/* Includes ------------------------------------------------------------------*/
#include "main.h"
#include "tim.h"
#include "usart.h"
#include "gpio.h"/* Private includes ----------------------------------------------------------*/
/* USER CODE BEGIN Includes */
#include "lcd.h"
#include "stdio.h"
#include "stdlib.h"
#include "string.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 *//* 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 */
//按鍵四種狀態
enum{key_released = 0U,key_reduction,key_pressed,key_wait_released,
};//停車位狀態
typedef struct {uint8_t CNBR;uint8_t VNBR;uint8_t IDLE;
} parking_t;
parking_t parking_spaces = {0, 0, 8};//存儲解析uart數據
typedef struct {char parking_type[5];char car_num[5];char time[15];
}parking_flag_t;
parking_flag_t parking_flag[8] = {0}, parking_flag_temporary = {0};//將時間字符串解析成數據
typedef struct{uint16_t years;uint8_t dates;uint8_t days;uint8_t hours;uint8_t minutes;uint8_t seconds;
}calendar_t;
calendar_t parking_time[8] = {0},parking_time_temporary = {0};/*
lcd_show_conv: lcd界面切換
pa7_pwm_ctrl: pwm輸出控制
lcd_clear_flag: 清屏標志
ld_flag: ld狀態標志
*/
uint8_t lcd_show_conv = 0, pa7_pwm_ctrl = 0, lcd_clear_flag = 0, ld_flag = 0;
/*
uart_rx_data: 接收來自串口的24字節的數據
lcd_str: lcd顯示
parking_fee_str: 串口回復收費信息buff
*/
uint8_t uart_rx_data[25] = {0}, lcd_str[21] = {0}, parking_fee_str[25] = {0};
//消抖時間標記
uint32_t key_redu_tim = 0;
/*
keys_volt: 按鍵電平信息
keys_state: 按鍵狀態信息
*/
uint8_t keys_volt[4] = {0}, keys_state[4] = {0};
/*
C_money: CNBR停車收費元/小時
V_money: VNBR停車收費元/小時
parking_fee: 計算停車費
*/
float C_money = 3.5f, V_money = 2.0f, parking_fee = 0.0f;void key_state_gain();
void key_process();
void lcd_process();
uint8_t analyze_uart_str(uint8_t *str);
uint8_t find_free_parking();
uint8_t find_car_in_parking(parking_flag_t p);
uint32_t caculate_parking_time(uint8_t i);
void led_process();/* 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 */LCD_Init();LCD_Clear(Black);LCD_SetBackColor(Black);LCD_SetTextColor(White);/* 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();MX_TIM17_Init();/* USER CODE BEGIN 2 */HAL_TIM_Base_Start_IT(&htim2);HAL_TIM_PWM_Start_IT(&htim17, TIM_CHANNEL_1);HAL_UARTEx_ReceiveToIdle_IT(&huart1, uart_rx_data, 24);/* USER CODE END 2 *//* Infinite loop *//* USER CODE BEGIN WHILE */while (1){/* USER CODE END WHILE *//* USER CODE BEGIN 3 */key_state_gain();key_process();lcd_process();led_process();}/* USER CODE END 3 */
}/*** @brief System Clock Configuration* @retval None*/
void SystemClock_Config(void)
{RCC_OscInitTypeDef RCC_OscInitStruct = {0};RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};/** Configure the main internal regulator output voltage*/HAL_PWREx_ControlVoltageScaling(PWR_REGULATOR_VOLTAGE_SCALE1_BOOST);/** 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_DIV6;RCC_OscInitStruct.PLL.PLLN = 85;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_4) != HAL_OK){Error_Handler();}
}/* USER CODE BEGIN 4 */
/* 獲取按鍵狀態 */
void key_state_gain()
{keys_volt[0] = HAL_GPIO_ReadPin(GPIOB, GPIO_PIN_0);keys_volt[1] = HAL_GPIO_ReadPin(GPIOB, GPIO_PIN_1);keys_volt[2] = HAL_GPIO_ReadPin(GPIOB, GPIO_PIN_2);keys_volt[3] = HAL_GPIO_ReadPin(GPIOA, GPIO_PIN_0);for(int i=0;i<4;i++){if(keys_volt[i] == 0){if(keys_state[i] == key_released){key_redu_tim = HAL_GetTick();keys_state[i] = key_reduction;}else if(keys_state[i] == key_reduction){if(HAL_GetTick() - key_redu_tim>=10){keys_state[i] = key_pressed;}}else if(keys_state[i] == key_pressed)keys_state[i] = key_wait_released;}else{if(keys_state[i] == key_wait_released || keys_state[i] == key_pressed){key_redu_tim = HAL_GetTick();keys_state[i] = key_reduction;}else if(keys_state[i] == key_reduction){if(HAL_GetTick() - key_redu_tim>=10){keys_state[i] = key_released;}}else keys_state[i] = key_released;     }}
}
/* 根據按鍵狀態設置對應標志 */
void key_process()
{if(keys_state[0] == key_pressed){ //界面切換lcd_show_conv ^= 1;}if(lcd_show_conv == 1){   //B2B3只在界面1起作用if(keys_state[1] == key_pressed){  //++C_money+= 0.5;V_money+= 0.5;}if(keys_state[2] == key_pressed){ //--C_money-= 0.5;V_money-= 0.5;if(V_money < 0) {C_money = 1.5;V_money = 0.0f;}}}if(keys_state[3] == key_pressed){   //pwm控制pa7_pwm_ctrl ^= 1;}
}
/* lcd兩種狀態 */
void lcd_process()
{switch(lcd_show_conv){case 0:if(lcd_clear_flag == 1){lcd_clear_flag = 0;LCD_Clear(Black);}sprintf((char*)lcd_str, "        Data        ");LCD_DisplayStringLine(Line2, lcd_str);sprintf((char*)lcd_str, "  CNBR:%d            ", parking_spaces.CNBR);LCD_DisplayStringLine(Line4, lcd_str);sprintf((char*)lcd_str, "  VNBR:%d            ", parking_spaces.VNBR);LCD_DisplayStringLine(Line6, lcd_str);sprintf((char*)lcd_str, "  IDLE:%d            ", parking_spaces.IDLE);LCD_DisplayStringLine(Line8, lcd_str);break;case 1:if(lcd_clear_flag == 0){lcd_clear_flag = 1;LCD_Clear(Black);}sprintf((char*)lcd_str, "        Data        ");LCD_DisplayStringLine(Line2, lcd_str);sprintf((char*)lcd_str, "  CNBR:%.2f         ", C_money);LCD_DisplayStringLine(Line4, lcd_str);sprintf((char*)lcd_str, "  VNBR:%.2f         ", V_money);LCD_DisplayStringLine(Line6, lcd_str);break;}
}
/**
*   @brief 判斷uart接收到的數據格式是否正確，這里只有長度判斷、車位類型、車位號碼、時間格式的判斷，
*   還可以加時間的大小比如月份只能是1~12月。還有解析時間的時候，假如說要取車，那取車時間肯定大于停車時間……
*   @para str: uart接收數據
*   @retval 1：數據格式錯誤，0：正確
*/
uint8_t analyze_uart_str(uint8_t *str)
{if(strlen((char*)str) != 24){  //return 1;}else{uint8_t *p = str;if(*p == 'C' || *p == 'V' && !strncasecmp((char*)p+1, "NBR", 3)) {strncpy(parking_flag_temporary.parking_type, (char*)str, 4);  }else return 1;for(p = str+5;p<str+9;p++){if(*p<0 || *p>127) return 1;}strncpy(parking_flag_temporary.car_num, (char*)str+5, 4);for(p = str+10; *p!='\0';p++){if(*p<'0' || *p > '9') return 1;}strncpy(parking_flag_temporary.time, (char*)str+10, 14);sscanf(parking_flag_temporary.time,"%4hu%2hhu%2hhu%2hhu%2hhu%2hhu", &parking_time_temporary.years, &parking_time_temporary.dates, &parking_time_temporary.days,&parking_time_temporary.hours, &parking_time_temporary.minutes, &parking_time_temporary.seconds);}return 0;
}
/* 查找是否有空閑車位 */
uint8_t find_free_parking()
{for(uint8_t i=0;i<8;i++){if(parking_flag[i].parking_type[0] != 'V' && parking_flag[i].parking_type[0] != 'C'){return i;}}return 8;
}
/* 查找是否該車要取車 */
uint8_t find_car_in_parking(parking_flag_t p)
{for(uint8_t i=0;i<8;i++){if(!strncasecmp(parking_flag[i].parking_type, p.parking_type, 4) && !strncasecmp(parking_flag[i].car_num, p.car_num, 4)){return i;}}return 8;
}
/* 停車時間計算 */
uint32_t caculate_parking_time(uint8_t i)
{uint32_t hour = 0;hour = (parking_time_temporary.years - parking_time[i].years)*365*24;hour += (parking_time_temporary.dates - parking_time[i].dates)*30*24;hour += (parking_time_temporary.days - parking_time[i].days)*24;hour += (parking_time_temporary.hours - parking_time[i].hours);if((parking_time_temporary.minutes-parking_time[i].minutes) >0 ||(parking_time_temporary.seconds-parking_time[i].seconds) > 0){hour++;}return hour;
}
/* led狀態更新 */
void led_process()
{if(parking_spaces.IDLE > 0){ld_flag = 1;}else ld_flag = 0;if(pa7_pwm_ctrl == 1){ld_flag += 1<<1;}else ld_flag += 0<< 1;HAL_GPIO_WritePin(GPIOD,GPIO_PIN_2, 1);GPIOC->ODR = 0xffff ^ ld_flag << 8;HAL_GPIO_WritePin(GPIOD,GPIO_PIN_2, 0);
}
/* 定時開啟uart接收中斷1s */
void HAL_TIM_PeriodElapsedCallback(TIM_HandleTypeDef *htim)
{HAL_UARTEx_ReceiveToIdle_IT(&huart1, uart_rx_data, 24);
}
/* pa7pwm輸出 */
void HAL_TIM_PWM_PulseFinishedCallback(TIM_HandleTypeDef *htim)
{if(pa7_pwm_ctrl == 1) TIM17->CCR1 = 999;else TIM17->CCR1 = 0;
}
/* uart接收數據處理 */
void HAL_UARTEx_RxEventCallback(UART_HandleTypeDef *huart, uint16_t Size)
{if(analyze_uart_str(uart_rx_data))   //分析數據格式是否正確，錯誤傳輸Error{HAL_UART_Transmit_IT(&huart1, (uint8_t*)"Error", 7); }/*格式正確處理順序 ：判斷是否是取車（停車場已有該車）-> 是: 取車+計算收費, 否: 判斷是否有空閑車位 -> 是：停車計時，否：不做處理*/else{                                     uint8_t i = find_car_in_parking(parking_flag_temporary); if(i != 8){   //表示取車if(!strcmp(parking_flag_temporary.parking_type, "VNBR")){    //計算停車費parking_fee = caculate_parking_time(i)*V_money;parking_spaces.VNBR--;parking_spaces.IDLE++;}else if(!strcmp(parking_flag_temporary.parking_type, "CNBR")){parking_fee = caculate_parking_time(i)*C_money;parking_spaces.CNBR--;parking_spaces.IDLE++;}sprintf((char*)parking_fee_str, "%4s:%4s:%u:%.2f", parking_flag_temporary.parking_type,parking_flag_temporary.car_num, caculate_parking_time(i), parking_fee);HAL_UART_Transmit_IT(&huart1, parking_fee_str, strlen((char*)parking_fee_str));memset(&parking_flag[i], 0, sizeof(parking_flag[i]));memset(&parking_time[i], 0, sizeof(parking_time[i]));}else{        //停車          i = find_free_parking();              if(i!=8){               //有空閑車位parking_flag[i] = parking_flag_temporary;parking_time[i] = parking_time_temporary;if(!strcmp(parking_flag_temporary.parking_type, "CNBR")){parking_spaces.CNBR++;parking_spaces.IDLE--;}else if(!strcmp(parking_flag_temporary.parking_type, "VNBR")){parking_spaces.VNBR++;parking_spaces.IDLE--;}}}}
}/* 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 */

3.第十二屆題目