GPIO
1、创建完工程之后，会出现编译警告出错问题，解决方法可以参考以下注释，因此新建工程后，必须在工程选项卡当中，【C/C++】中的全局宏定义添加"USE_STDPERIPH_DRIVER"，即这个定义控制了是否在应用中启用外设驱动。我们使用标准外设库本来就为了方便控制外设，所以要添加这个定义，以启用外设驱动。
在stm32f4xx.h文件中，说明如下：
1）USE_STDPERIPH_DRIVER宏定义
/** ****************************************************************************** * @file stm32f4xx.h * @author MCD Application Team * @version V1.3.0 modified by Keil (added USB definitions) * @date 08-November-2013 * @brief CMSIS Cortex-M4 Device Peripheral Access Layer Header File. * This file contains all the peripheral register's definitions, bits * definitions and memory mapping for STM32F4xx devices. * * The file is the unique include file that the application programmer * is using in the C source code, usually in main.c. This file contains: * - Configuration section that allows to select: * - The device used in the target application * - To use or not the peripheral’s drivers in application code(i.e. //对于是否启用外设驱动，决定于USE_STDPERIPH_DRIVER * code will be based on direct access to peripheral’s registers * rather than drivers API), this option is controlled by * "#define USE_STDPERIPH_DRIVER" * - To change few application-specific parameters such as the HSE * crystal frequency * - Data structures and the address mapping for all peripherals * - Peripheral's registers declarations and bits definition * - Macros to access peripheral’s registers hardware * ******************************************************************************
2） .\Objects\project.axf: Error: L6218E: Undefined symbol RCC_AHB1PeriphResetCmd (referred from stm32f4xx_gpio.o).
解决方法：在Keil5 添加RCC的库函数。
2、添加头文件路径，在工程选项卡当中，【C/C++】中的“Include Paths”添加相应的头文件路径，否则这些文件会出现感叹号，编译器说找不到。
.\RTE\Device\STM32F407ZE;.\RTE
上述包含两个头文件路径，不同的头文件路径以分号进行隔离。
3、编译的时候，总是出现以下警告，
main.c(8): warning: #1-D: last line of file ends without a newline //文件末尾没有新行
解决方法：每个公司都有自己的编写代码规范，都需要看到回车换行，在文件末尾按一下回车键。
4、设置Keil编译完之后，生成Hex文件。
在工程选项【output】的标签，勾选“Create HEX File”。
重新编译之后，就生成一下信息。
Build target 'led'
Build target 'led'
FromELF: creating hex file...
"
.\Objects\project.axf" - 0 Error(s), 0 Warning(s).
"
.\Objects\project.axf" - 0 Error(s), 0 Warning(s).
三、GPIO的库函数
/** * @brief Sets the selected data port bits. //设置选择好的端口的引脚电平，说白将对应的引脚变为高电平 * @note This functions uses GPIOx_BSRR register to allow atomic read/modify * accesses. In this way, there is no risk of an IRQ occurring between * the read and the modify access. * @param GPIOx: where x can be (A..K) to select the GPIO peripheral for STM32F405xx/407xx and STM32F415xx/417xx devices * x can be (A..I) to select the GPIO peripheral for STM32F42xxx/43xxx devices. * x can be (A, B, C, D and H) to select the GPIO peripheral for STM32F401xx devices. * @param GPIO_Pin: specifies the port bits to be written. * This parameter can be any combination of GPIO_Pin_x where x can be (0..15). * @retval None */ void GPIO_SetBits(GPIO_TypeDef* GPIOx, uint16_t GPIO_Pin) /** * @brief Clears the selected data port bits. //清空选择好的端口的引脚电平，说白将对应的引脚变为低电平 * @note This functions uses GPIOx_BSRR register to allow atomic read/modify * accesses. In this way, there is no risk of an IRQ occurring between * the read and the modify access. * @param GPIOx: where x can be (A..K) to select the GPIO peripheral for STM32F405xx/407xx and STM32F415xx/417xx devices * x can be (A..I) to select the GPIO peripheral for STM32F42xxx/43xxx devices. * x can be (A, B, C, D and H) to select the GPIO peripheral for STM32F401xx devices. * @param GPIO_Pin: specifies the port bits to be written. * This parameter can be any combination of GPIO_Pin_x where x can be (0..15). * @retval None */ void GPIO_ResetBits(GPIO_TypeDef* GPIOx, uint16_t GPIO_Pin)
四、通过J-Link仿真下载器进行下载代码
1）J-Link正确连接到开发板
2）安装驱动Setup_JLinkARM_V415e.exe
3）在工程选项的【Debug】标签，选中“J-LINK/J-TRACE Cortex”,接着点击“settings”，设置port为“sw”，频率为“5MHz”；然后点击【Flash Download】，勾选“Reset and Run”。最后点击“确定”按钮退出。
4）在Keil5 界面当中，点击“Download”图标，就可以进行程序下载。
五、使用库函数编程技巧
1、阅读硬件原理图《GEC-M4原理图2016-07-29.pdf》，了解当前需要使用STM32芯片哪个硬件，就可以知道使用哪些库函数接口。
2、使用库函数的时候，只需要了解该函数的使用方法，如传入参数、返回值、功能描述就足矣。库函数里面的编写内容不需要了解，这些代码都是由ST公司去实现的。
3、如何使用库函数实现一个具体的功能，ST公司都会提供例子文档，告诉我们库函数如何使用，无论是新手还是老手都要看的。
.STM32F4xx中文参考手册.pdf
.stm32f4xx_dsp_stdperiph_lib_um.chm
.STM32F4xx中文参考手册.pdf
.stm32f4xx_dsp_stdperiph_lib_um.chm
#include <stdio.h> #include "stm32f4xx.h" GPIO_InitTypeDef GPIO_InitStructure; void delay(void) { int i=0x500000; while(i--); } int main(void) { /* GPIOF Peripheral clock enable，使能GPIO第F组的端口硬件时钟 */ RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOF, ENABLE); /* Configure PF10 in output pushpull mode，配置PF10引脚为输出模式 */ GPIO_InitStructure.GPIO_Pin = GPIO_Pin_9; //第9根引脚 GPIO_InitStructure.GPIO_Mode = GPIO_Mode_OUT; //设置输出模式 GPIO_InitStructure.GPIO_OType = GPIO_OType_PP; //推挽模式，增加驱动电流 GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz; //设置IO的速度为100MHz GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL; //不需要上拉电阻 GPIO_Init(GPIOF, &GPIO_InitStructure); while(1) { //设置PF9引脚为高电平 GPIO_SetBits(GPIOF,GPIO_Pin_9); delay(); //设置PF9引脚为低电平 GPIO_ResetBits(GPIOF,GPIO_Pin_9); delay(); } }
1.配置引脚为输入模式
/* 配置PA0引脚为输入模式 */ GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0; //第0根引脚 GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN; //设置输入模式[重点修改] GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz; //设置IO的速度为100MHz GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL; //不需要上拉电阻 GPIO_Init(GPIOF, &GPIO_InitStructure);
2.读取电平
a.读取整个端口的电平(0~15号的引脚的电平都能够同时进行读取)
/** * @brief Reads the specified GPIO input data port. * @param GPIOx: where x can be (A..K) to select the GPIO peripheral for STM32F405xx/407xx and STM32F415xx/417xx devices * x can be (A..I) to select the GPIO peripheral for STM32F42xxx/43xxx devices. * x can be (A, B, C, D and H) to select the GPIO peripheral for STM32F401xx devices. * @retval GPIO input data port value. */ uint16_t GPIO_ReadInputData(GPIO_TypeDef* GPIOx)
b.读取端口某个引脚的电平值
/** * @brief Reads the specified input port pin. * @param GPIOx: where x can be (A..K) to select the GPIO peripheral for STM32F405xx/407xx and STM32F415xx/417xx devices * x can be (A..I) to select the GPIO peripheral for STM32F42xxx/43xxx devices. * x can be (A, B, C, D and H) to select the GPIO peripheral for STM32F401xx devices. * @param GPIO_Pin: specifies the port bit to read. * This parameter can be GPIO_Pin_x where x can be (0..15). * @retval The input port pin value. */ uint8_t GPIO_ReadInputDataBit(GPIO_TypeDef* GPIOx, uint16_t GPIO_Pin)
