Bootloader

Posted 2023-02-06 tommybjia

一、           实验目的和要求

1.     理解uboot等bootloader的一般功能和基本工作原理；

2.     掌握在STM32F上编写逻辑程序并下载运行的方法。

 

二、           实验器材

1.     STM32F103核心板一块；

2.     MicroUSB线一根；

3.     STLink板或USB串口板一块；

4.     交叉编译软件

 

三、           实验内容和原理

1．写一个自己的简易bootloader，能通过串口执行两条最简单的指令

a)       Peek addr以一个字为单位读取内存中addr位置的数据（addr是4字节对齐，十六进制的形式，长度为8位十六进制，例如0x00008000），并以十六进制的形式输出；

b)       Poke addr data以一个字为单位修改内存中addr位置的数据为data（addr是4字节对齐，十六进制的形式，长度为8位十六进制，data也是十六进制的形式，长度为8位十六进制）

 

四、           实验过程和数据记录

1.     下面是实物连接图.ST-LINK与STM32开发板的连接如下

2.     设置PA9为TX，PA10为RX，并且配置串口参数，波特率为9600，8n1

3.     设置后生成代码，设置为MDK-ARM V5项目，并且打开Keli MDK，修改其中main.c函数内容。

4.     实现的bootloader代码如下，主要实现其两个功能，分别为peek和poke功能。以下是修改之后main.c的代码

/**   ******************************************************************************   * File Name          : main.c   * Description        : Main program body   ******************************************************************************   *   * COPYRIGHT(c) 2016 STMicroelectronics   *   * Redistribution and use in source and binary forms, with or without modification,   * are permitted provided that the following conditions are met:   *   1. Redistributions of source code must retain the above copyright notice,   *      this list of conditions and the following disclaimer.   *   2. Redistributions in binary form must reproduce the above copyright notice,   *      this list of conditions and the following disclaimer in the documentation   *      and/or other materials provided with the distribution.   *   3. Neither the name of STMicroelectronics nor the names of its contributors   *      may be used to endorse or promote products derived from this software   *      without specific prior written permission.   *   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"   * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE   * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE   * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL   * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR   * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER   * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,   * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE   * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.   *   ******************************************************************************   */ /* Includes ------------------------------------------------------------------*/ #include "stm32f1xx_hal.h"   /* USER CODE BEGIN Includes */ #include <string.h>   /* USER CODE END Includes */   /* Private variables ---------------------------------------------------------*/ UART_HandleTypeDef huart1;   /* USER CODE BEGIN PV */ /* Private variables ---------------------------------------------------------*/ int UserAppStarting = 0x08003000;   /* USER CODE END PV */   /* Private function prototypes -----------------------------------------------*/ void SystemClock_Config(void); static void MX_GPIO_Init(void); static void MX_USART1_UART_Init(void);   /* USER CODE BEGIN PFP */ /* Private function prototypes -----------------------------------------------*/   /* USER CODE END PFP */   /* USER CODE BEGIN 0 */   /* USER CODE END 0 */   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();     /* Configure the system clock */   SystemClock_Config();     /* Initialize all configured peripherals */   MX_GPIO_Init();   MX_USART1_UART_Init();     /* USER CODE BEGIN 2 */        uint32_t test = 0x33333333;               char uchar[10] = 0;        uint32_t addr, data;     /* USER CODE END 2 */     /* Infinite loop */   /* USER CODE BEGIN WHILE */        printf("This is Bootloader!\\r\\n");        printf("addr: 0x%08x\\r\\nval: 0x%08x\\r\\n", &test, test);   while (1)     /* USER CODE END WHILE */     /* USER CODE BEGIN 3 */               printf("Command(peek or poke):\\r\\n");               scanf("%s", uchar);               scanf("%x", &addr);                             if (strcmp(uchar, "peek") == 0)                                    printf("Data at 0x%08x: 0x%08x\\r\\n", addr, *((uint32_t *)addr));                             else if (strcmp(uchar, "poke") == 0)                                    printf("Data is:\\r\\n");                      scanf("%x", &data);                      *((uint32_t *)addr) = data;                      printf("Change in 0x%08x: 0x%08x\\r\\n", addr, data);                   /* USER CODE END 3 */     /** System Clock Configuration */ void SystemClock_Config(void)     RCC_OscInitTypeDef RCC_OscInitStruct;   RCC_ClkInitTypeDef RCC_ClkInitStruct;     RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI;   RCC_OscInitStruct.HSIState = RCC_HSI_ON;   RCC_OscInitStruct.HSICalibrationValue = 16;   RCC_OscInitStruct.PLL.PLLState = RCC_PLL_NONE;   HAL_RCC_OscConfig(&RCC_OscInitStruct);     RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK                               |RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2;   RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_HSI;   RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;   RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV1;   RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;   HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_0);     HAL_SYSTICK_Config(HAL_RCC_GetHCLKFreq()/1000);     HAL_SYSTICK_CLKSourceConfig(SYSTICK_CLKSOURCE_HCLK);     /* SysTick_IRQn interrupt configuration */   HAL_NVIC_SetPriority(SysTick_IRQn, 0, 0);   /* USART1 init function */ void MX_USART1_UART_Init(void)     huart1.Instance = USART1;   huart1.Init.BaudRate = 9600;   huart1.Init.WordLength = UART_WORDLENGTH_8B;   huart1.Init.StopBits = UART_STOPBITS_1;   huart1.Init.Parity = UART_PARITY_NONE;   huart1.Init.Mode = UART_MODE_TX_RX;   huart1.Init.HwFlowCtl = UART_HWCONTROL_NONE;   huart1.Init.OverSampling = UART_OVERSAMPLING_16;   HAL_UART_Init(&huart1);     /** Pinout Configuration */ void MX_GPIO_Init(void)     /* GPIO Ports Clock Enable */   __HAL_RCC_GPIOA_CLK_ENABLE();     /* USER CODE BEGIN 4 */ int fputc(int ch, FILE *f)   /* Place your implementation of fputc here */   /* e.g. write a character to the USART1 and Loop until the end of transmission */   HAL_UART_Transmit(&huart1, (uint8_t *)&ch, 1, 0xFFFF);     return ch; int fgetc(FILE *f)        uint8_t ch;        HAL_UART_Receive(&huart1, (uint8_t *)&ch, 1, 0xFFFF);        if (ch == 0x0d)                      fputc(0x0d, f);               fputc(0x0a, f);               else                      fputc(ch, f);                      return ch;   /* USER CODE END 4 */   #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   /**   * @   */   /**   * @ */   /************************ (C) COPYRIGHT STMicroelectronics *****END OF FILE****/

 

5.     实验操作结果如下：

首先使用peek查看地址为2000044c的数据，为0x33333333(初始设置值，在代码中可以看到)，之后通过poke修改为0x11111111，再通过peek看是否修改成功。由图可知实验顺利输出修改后的值。