一、STM32寄存器结构体

? 对于STM32而言，使用一个结构体将一个外设的所有寄存器都放到一起。将结构体抽象为硬件的外设寄存器，给结构体一个基地址，成员变量的地址自动偏移。
仿照STM32库函数的方式，编写I.MX6UL的LED驱动。

二、修改驱动

? 1、添加清除bss段代码

? imx6ul.lds

SECTIONS{
    . =0X87800000;
    .text :
    {
        start.o
        (*.text)
    }
    .rodata ALIGN(4) : {*(.rodata)}
    .data   ALIGN(4) : {*(.data)}
    __bss_start =.;
    .bss ALIGN(4) :{*(.bss) *(COMMON)}
    __bss_end = .;
}

启动文件start.S


.global _start

/* bss定义但未初始化变量的区域 */
.global __bss_start
_bss_start:
	.word __bss_start

.global __bss_end
_bss_end:
	.word __bss_end

_start:
    /* 进入SVC */
    mrs r0,cpsr         /* r0读取cpsr的数值 */
    bic r0,r0,#0x1f     /* 清除低5位，r0 = r0&（~0x1f） */
    orr r0,r0,#0x13     /* 写入低5位，r0 = r0|0x13 */
    msr cpsr,r0         /* r0的值写入cpsr */

    /* 清除bss区 */
    ldr r0,_bss_start
    ldr r1,_bss_end
    mov r2,#0   
bss_loop:
    stmia r0!,{r2}    /*stmia r2的值写入r0地址，r0地址自增*/
    cmp   r0,r1       /* 比较r0，r1的大小 */
    ble   bss_loop    /* r0<=r1 跳转到bss_loop */

    /* 设置sp栈指针，跳转到main函数 */
    ldr sp,= 0x80200000
    b main

? 2、添加寄存器结构体

? 在结构体中添加寄存器的时候一定要注意地址的连续性，如果不连续的话要添加占位。RESERVED_2[2];占俩个位置

imx6ul.h

#ifndef _IMX6UL_H
#define _IMX6UL_H

/* 
 * 外设寄存器组的基地址 
 */
#define CCM_BASE					(0X020C4000)
#define CCM_ANALOG_BASE				(0X020C8000)
#define IOMUX_SW_MUX_BASE			(0X020E0014)
#define IOMUX_SW_PAD_BASE			(0X020E0204)
#define GPIO1_BASE                  (0x0209C000)
#define GPIO2_BASE                  (0x020A0000)
#define GPIO3_BASE                  (0x020A4000)
#define GPIO4_BASE                  (0x020A8000)
#define GPIO5_BASE                  (0x020AC000)

/* 
 * CCM寄存器结构体定义，分为CCM和CCM_ANALOG 
 */
typedef struct 
{
	volatile unsigned int CCR;
	volatile unsigned int CCDR;
	volatile unsigned int CSR;
	volatile unsigned int CCSR;
	volatile unsigned int CACRR;
	volatile unsigned int CBCDR;
	volatile unsigned int CBCMR;
	volatile unsigned int CSCMR1;
	volatile unsigned int CSCMR2;
	volatile unsigned int CSCDR1;
	volatile unsigned int CS1CDR;
	volatile unsigned int CS2CDR;
	volatile unsigned int CDCDR;
	volatile unsigned int CHSCCDR;
	volatile unsigned int CSCDR2;
	volatile unsigned int CSCDR3;	
	volatile unsigned int RESERVED_1[2];
	volatile unsigned int CDHIPR;  
	volatile unsigned int RESERVED_2[2];
	volatile unsigned int CLPCR;
	volatile unsigned int CISR;
	volatile unsigned int CIMR;
	volatile unsigned int CCOSR;
	volatile unsigned int CGPR;
	volatile unsigned int CCGR0;
	volatile unsigned int CCGR1;
	volatile unsigned int CCGR2;
	volatile unsigned int CCGR3;
	volatile unsigned int CCGR4;
	volatile unsigned int CCGR5;
	volatile unsigned int CCGR6;
	volatile unsigned int RESERVED_3[1];
	volatile unsigned int CMEOR;	
} CCM_Type; 

typedef struct 
{
	volatile unsigned int PLL_ARM;
	volatile unsigned int PLL_ARM_SET;
	volatile unsigned int PLL_ARM_CLR;
	volatile unsigned int PLL_ARM_TOG;
	volatile unsigned int PLL_USB1;
	volatile unsigned int PLL_USB1_SET;
	volatile unsigned int PLL_USB1_CLR;
	volatile unsigned int PLL_USB1_TOG;
	volatile unsigned int PLL_USB2;
	volatile unsigned int PLL_USB2_SET;
	volatile unsigned int PLL_USB2_CLR;
	volatile unsigned int PLL_USB2_TOG;
	volatile unsigned int PLL_SYS;
	volatile unsigned int PLL_SYS_SET;
	volatile unsigned int PLL_SYS_CLR;
	volatile unsigned int PLL_SYS_TOG;
	volatile unsigned int PLL_SYS_SS;
	volatile unsigned int RESERVED_1[3];
	volatile unsigned int PLL_SYS_NUM;
	volatile unsigned int RESERVED_2[3];
	volatile unsigned int PLL_SYS_DENOM; 
	volatile unsigned int RESERVED_3[3];
	volatile unsigned int PLL_AUDIO;
	volatile unsigned int PLL_AUDIO_SET;
	volatile unsigned int PLL_AUDIO_CLR;
	volatile unsigned int PLL_AUDIO_TOG;
	volatile unsigned int PLL_AUDIO_DENOM;
	volatile unsigned int RESERVED_4[3];
	volatile unsigned int PLL_VIDEO;
	volatile unsigned int PLL_VIDEO_SET;
	volatile unsigned int PLL_VIDEO_CLR;
	volatile unsigned int PLL_VIDEO_TOG;
	volatile unsigned int PLL_VIDEO_NUM;
	volatile unsigned int RESERVED_5[3];
	volatile unsigned int PLL_VIDEO_DENOM;
	volatile unsigned int RESERVED_6[7];
	volatile unsigned int PLL_ENET;
	volatile unsigned int PLL_ENET_SET;
	volatile unsigned int PLL_ENET_CLR;
	volatile unsigned int PLL_ENET_TOG;
	volatile unsigned int PFD_480;
	volatile unsigned int PFD_480_SET;
	volatile unsigned int PFD_480_CLR;
	volatile unsigned int PFD_480_TOG;
	volatile unsigned int PFD_528;
	volatile unsigned int PFD_528_SET;
	volatile unsigned int PFD_528_CLR;
	volatile unsigned int PFD_528_TOG;
	volatile unsigned int RESERVED_7[16];
	volatile unsigned int MISC0;
	volatile unsigned int MISC0_SET;
	volatile unsigned int MISC0_CLR;
	volatile unsigned int MISC0_TOG;
	volatile unsigned int MISC1;
	volatile unsigned int MISC1_SET;
	volatile unsigned int MISC1_CLR;
	volatile unsigned int MISC1_TOG;
	volatile unsigned int MISC2;
	volatile unsigned int MISC2_SET;
	volatile unsigned int MISC2_CLR;
	volatile unsigned int MISC2_TOG;
} CCM_ANALOG_Type; 

/* 
 * IOMUX寄存器组
 */
typedef struct 
{
	volatile unsigned int BOOT_MODE0;
	volatile unsigned int BOOT_MODE1;
	volatile unsigned int SNVS_TAMPER0;
	volatile unsigned int SNVS_TAMPER1;
	volatile unsigned int SNVS_TAMPER2;
	volatile unsigned int SNVS_TAMPER3;
	volatile unsigned int SNVS_TAMPER4;
	volatile unsigned int SNVS_TAMPER5;
	volatile unsigned int SNVS_TAMPER6;
	volatile unsigned int SNVS_TAMPER7;
	volatile unsigned int SNVS_TAMPER8;
	volatile unsigned int SNVS_TAMPER9;
	volatile unsigned int JTAG_MOD;
	volatile unsigned int JTAG_TMS;
	volatile unsigned int JTAG_TDO;
	volatile unsigned int JTAG_TDI;
	volatile unsigned int JTAG_TCK;
	volatile unsigned int JTAG_TRST_B;
	volatile unsigned int GPIO1_IO00;
	volatile unsigned int GPIO1_IO01;
	volatile unsigned int GPIO1_IO02;
	volatile unsigned int GPIO1_IO03;
	volatile unsigned int GPIO1_IO04;
	volatile unsigned int GPIO1_IO05;
	volatile unsigned int GPIO1_IO06;
	volatile unsigned int GPIO1_IO07;
	volatile unsigned int GPIO1_IO08;
	volatile unsigned int GPIO1_IO09;
	volatile unsigned int UART1_TX_DATA;
	volatile unsigned int UART1_RX_DATA;
	volatile unsigned int UART1_CTS_B;
	volatile unsigned int UART1_RTS_B;
	volatile unsigned int UART2_TX_DATA;
	volatile unsigned int UART2_RX_DATA;
	volatile unsigned int UART2_CTS_B;
	volatile unsigned int UART2_RTS_B;
	volatile unsigned int UART3_TX_DATA;
	volatile unsigned int UART3_RX_DATA;
	volatile unsigned int UART3_CTS_B;
	volatile unsigned int UART3_RTS_B;
	volatile unsigned int UART4_TX_DATA;
	volatile unsigned int UART4_RX_DATA;
	volatile unsigned int UART5_TX_DATA;
	volatile unsigned int UART5_RX_DATA;
	volatile unsigned int ENET1_RX_DATA0;
	volatile unsigned int ENET1_RX_DATA1;
	volatile unsigned int ENET1_RX_EN;
	volatile unsigned int ENET1_TX_DATA0;
	volatile unsigned int ENET1_TX_DATA1;
	volatile unsigned int ENET1_TX_EN;
	volatile unsigned int ENET1_TX_CLK;
	volatile unsigned int ENET1_RX_ER;
	volatile unsigned int ENET2_RX_DATA0;
	volatile unsigned int ENET2_RX_DATA1;
	volatile unsigned int ENET2_RX_EN;
	volatile unsigned int ENET2_TX_DATA0;
	volatile unsigned int ENET2_TX_DATA1;
	volatile unsigned int ENET2_TX_EN;
	volatile unsigned int ENET2_TX_CLK;
	volatile unsigned int ENET2_RX_ER;
	volatile unsigned int LCD_CLK;
	volatile unsigned int LCD_ENABLE;
	volatile unsigned int LCD_HSYNC;
	volatile unsigned int LCD_VSYNC;
	volatile unsigned int LCD_RESET;
	volatile unsigned int LCD_DATA00;
	volatile unsigned int LCD_DATA01;
	volatile unsigned int LCD_DATA02;
	volatile unsigned int LCD_DATA03;
	volatile unsigned int LCD_DATA04;
	volatile unsigned int LCD_DATA05;
	volatile unsigned int LCD_DATA06;
	volatile unsigned int LCD_DATA07;
	volatile unsigned int LCD_DATA08;
	volatile unsigned int LCD_DATA09;
	volatile unsigned int LCD_DATA10;
	volatile unsigned int LCD_DATA11;
	volatile unsigned int LCD_DATA12;
	volatile unsigned int LCD_DATA13;
	volatile unsigned int LCD_DATA14;
	volatile unsigned int LCD_DATA15;
	volatile unsigned int LCD_DATA16;
	volatile unsigned int LCD_DATA17;
	volatile unsigned int LCD_DATA18;
	volatile unsigned int LCD_DATA19;
	volatile unsigned int LCD_DATA20;
	volatile unsigned int LCD_DATA21;
	volatile unsigned int LCD_DATA22;
	volatile unsigned int LCD_DATA23;
	volatile unsigned int NAND_RE_B;
	volatile unsigned int NAND_WE_B;
	volatile unsigned int NAND_DATA00;
	volatile unsigned int NAND_DATA01;
	volatile unsigned int NAND_DATA02;
	volatile unsigned int NAND_DATA03;
	volatile unsigned int NAND_DATA04;
	volatile unsigned int NAND_DATA05;
	volatile unsigned int NAND_DATA06;
	volatile unsigned int NAND_DATA07;
	volatile unsigned int NAND_ALE;
	volatile unsigned int NAND_WP_B;
	volatile unsigned int NAND_READY_B;
	volatile unsigned int NAND_CE0_B;
	volatile unsigned int NAND_CE1_B;
	volatile unsigned int NAND_CLE;
	volatile unsigned int NAND_DQS;
	volatile unsigned int SD1_CMD;
	volatile unsigned int SD1_CLK;
	volatile unsigned int SD1_DATA0;
	volatile unsigned int SD1_DATA1;
	volatile unsigned int SD1_DATA2;
	volatile unsigned int SD1_DATA3;
	volatile unsigned int CSI_MCLK;
	volatile unsigned int CSI_PIXCLK;
	volatile unsigned int CSI_VSYNC;
	volatile unsigned int CSI_HSYNC;
	volatile unsigned int CSI_DATA00;
	volatile unsigned int CSI_DATA01;
	volatile unsigned int CSI_DATA02;
	volatile unsigned int CSI_DATA03;
	volatile unsigned int CSI_DATA04;
	volatile unsigned int CSI_DATA05;
	volatile unsigned int CSI_DATA06;
	volatile unsigned int CSI_DATA07;
}IOMUX_SW_MUX_Type;

typedef struct 
{
	volatile unsigned int DRAM_ADDR00;
	volatile unsigned int DRAM_ADDR01;
	volatile unsigned int DRAM_ADDR02;
	volatile unsigned int DRAM_ADDR03;
	volatile unsigned int DRAM_ADDR04;
	volatile unsigned int DRAM_ADDR05;
	volatile unsigned int DRAM_ADDR06;
	volatile unsigned int DRAM_ADDR07;
	volatile unsigned int DRAM_ADDR08;
	volatile unsigned int DRAM_ADDR09;
	volatile unsigned int DRAM_ADDR10;
	volatile unsigned int DRAM_ADDR11;
	volatile unsigned int DRAM_ADDR12;
	volatile unsigned int DRAM_ADDR13;
	volatile unsigned int DRAM_ADDR14;
	volatile unsigned int DRAM_ADDR15;
	volatile unsigned int DRAM_DQM0;
	volatile unsigned int DRAM_DQM1;
	volatile unsigned int DRAM_RAS_B;
	volatile unsigned int DRAM_CAS_B;
	volatile unsigned int DRAM_CS0_B;
	volatile unsigned int DRAM_CS1_B;
	volatile unsigned int DRAM_SDWE_B;
	volatile unsigned int DRAM_ODT0;
	volatile unsigned int DRAM_ODT1;
	volatile unsigned int DRAM_SDBA0;
	volatile unsigned int DRAM_SDBA1;
	volatile unsigned int DRAM_SDBA2;
	volatile unsigned int DRAM_SDCKE0;
	volatile unsigned int DRAM_SDCKE1;
	volatile unsigned int DRAM_SDCLK0_P;
	volatile unsigned int DRAM_SDQS0_P;
	volatile unsigned int DRAM_SDQS1_P;
	volatile unsigned int DRAM_RESET;
	volatile unsigned int TEST_MODE;
	volatile unsigned int POR_B;
	volatile unsigned int ONOFF;
	volatile unsigned int SNVS_PMIC_ON_REQ;
	volatile unsigned int CCM_PMIC_STBY_REQ;
	volatile unsigned int BOOT_MODE0;
	volatile unsigned int BOOT_MODE1;
	volatile unsigned int SNVS_TAMPER0;
	volatile unsigned int SNVS_TAMPER1;
	volatile unsigned int SNVS_TAMPER2;
	volatile unsigned int SNVS_TAMPER3;
	volatile unsigned int SNVS_TAMPER4;
	volatile unsigned int SNVS_TAMPER5;
	volatile unsigned int SNVS_TAMPER6;
	volatile unsigned int SNVS_TAMPER7;
	volatile unsigned int SNVS_TAMPER8;
	volatile unsigned int SNVS_TAMPER9;
	volatile unsigned int JTAG_MOD;
	volatile unsigned int JTAG_TMS;
	volatile unsigned int JTAG_TDO;
	volatile unsigned int JTAG_TDI;
	volatile unsigned int JTAG_TCK;
	volatile unsigned int JTAG_TRST_B;
	volatile unsigned int GPIO1_IO00;
	volatile unsigned int GPIO1_IO01;
	volatile unsigned int GPIO1_IO02;
	volatile unsigned int GPIO1_IO03;
	volatile unsigned int GPIO1_IO04;
	volatile unsigned int GPIO1_IO05;
	volatile unsigned int GPIO1_IO06;
	volatile unsigned int GPIO1_IO07;
	volatile unsigned int GPIO1_IO08;
	volatile unsigned int GPIO1_IO09;
	volatile unsigned int UART1_TX_DATA;
	volatile unsigned int UART1_RX_DATA;
	volatile unsigned int UART1_CTS_B;
	volatile unsigned int UART1_RTS_B;
	volatile unsigned int UART2_TX_DATA;
	volatile unsigned int UART2_RX_DATA;
	volatile unsigned int UART2_CTS_B;
	volatile unsigned int UART2_RTS_B;
	volatile unsigned int UART3_TX_DATA;
	volatile unsigned int UART3_RX_DATA;
	volatile unsigned int UART3_CTS_B;
	volatile unsigned int UART3_RTS_B;
	volatile unsigned int UART4_TX_DATA;
	volatile unsigned int UART4_RX_DATA;
	volatile unsigned int UART5_TX_DATA;
	volatile unsigned int UART5_RX_DATA;
	volatile unsigned int ENET1_RX_DATA0;
	volatile unsigned int ENET1_RX_DATA1;
	volatile unsigned int ENET1_RX_EN;
	volatile unsigned int ENET1_TX_DATA0;
	volatile unsigned int ENET1_TX_DATA1;
	volatile unsigned int ENET1_TX_EN;
	volatile unsigned int ENET1_TX_CLK;
	volatile unsigned int ENET1_RX_ER;
	volatile unsigned int ENET2_RX_DATA0;
	volatile unsigned int ENET2_RX_DATA1;
	volatile unsigned int ENET2_RX_EN;
	volatile unsigned int ENET2_TX_DATA0;
	volatile unsigned int ENET2_TX_DATA1;
	volatile unsigned int ENET2_TX_EN;
	volatile unsigned int ENET2_TX_CLK;
	volatile unsigned int ENET2_RX_ER;
	volatile unsigned int LCD_CLK;
	volatile unsigned int LCD_ENABLE;
	volatile unsigned int LCD_HSYNC;
	volatile unsigned int LCD_VSYNC;
	volatile unsigned int LCD_RESET;
	volatile unsigned int LCD_DATA00;
	volatile unsigned int LCD_DATA01;
	volatile unsigned int LCD_DATA02;
	volatile unsigned int LCD_DATA03;
	volatile unsigned int LCD_DATA04;
	volatile unsigned int LCD_DATA05;
	volatile unsigned int LCD_DATA06;
	volatile unsigned int LCD_DATA07;
	volatile unsigned int LCD_DATA08;
	volatile unsigned int LCD_DATA09;
	volatile unsigned int LCD_DATA10;
	volatile unsigned int LCD_DATA11;
	volatile unsigned int LCD_DATA12;
	volatile unsigned int LCD_DATA13;
	volatile unsigned int LCD_DATA14;
	volatile unsigned int LCD_DATA15;
	volatile unsigned int LCD_DATA16;
	volatile unsigned int LCD_DATA17;
	volatile unsigned int LCD_DATA18;
	volatile unsigned int LCD_DATA19;
	volatile unsigned int LCD_DATA20;
	volatile unsigned int LCD_DATA21;
	volatile unsigned int LCD_DATA22;
	volatile unsigned int LCD_DATA23;
	volatile unsigned int NAND_RE_B;
	volatile unsigned int NAND_WE_B;
	volatile unsigned int NAND_DATA00;
	volatile unsigned int NAND_DATA01;
	volatile unsigned int NAND_DATA02;
	volatile unsigned int NAND_DATA03;
	volatile unsigned int NAND_DATA04;
	volatile unsigned int NAND_DATA05;
	volatile unsigned int NAND_DATA06;
	volatile unsigned int NAND_DATA07;
	volatile unsigned int NAND_ALE;
	volatile unsigned int NAND_WP_B;
	volatile unsigned int NAND_READY_B;
	volatile unsigned int NAND_CE0_B;
	volatile unsigned int NAND_CE1_B;
	volatile unsigned int NAND_CLE;
	volatile unsigned int NAND_DQS;
	volatile unsigned int SD1_CMD;
	volatile unsigned int SD1_CLK;
	volatile unsigned int SD1_DATA0;
	volatile unsigned int SD1_DATA1;
	volatile unsigned int SD1_DATA2;
	volatile unsigned int SD1_DATA3;
	volatile unsigned int CSI_MCLK;
	volatile unsigned int CSI_PIXCLK;
	volatile unsigned int CSI_VSYNC;
	volatile unsigned int CSI_HSYNC;
	volatile unsigned int CSI_DATA00;
	volatile unsigned int CSI_DATA01;
	volatile unsigned int CSI_DATA02;
	volatile unsigned int CSI_DATA03;
	volatile unsigned int CSI_DATA04;
	volatile unsigned int CSI_DATA05;
	volatile unsigned int CSI_DATA06;
	volatile unsigned int CSI_DATA07;
	volatile unsigned int GRP_ADDDS;
	volatile unsigned int GRP_DDRMODE_CTL;
	volatile unsigned int GRP_B0DS;
	volatile unsigned int GRP_DDRPK;
	volatile unsigned int GRP_CTLDS;
	volatile unsigned int GRP_B1DS;
	volatile unsigned int GRP_DDRHYS;
	volatile unsigned int GRP_DDRPKE;
	volatile unsigned int GRP_DDRMODE;
	volatile unsigned int GRP_DDR_TYPE;
}IOMUX_SW_PAD_Type;

/* 
 * GPIO寄存器结构体
 */
typedef struct 
{
	volatile unsigned int DR;							
	volatile unsigned int GDIR; 							
	volatile unsigned int PSR;								
	volatile unsigned int ICR1; 							
	volatile unsigned int ICR2; 							 
	volatile unsigned int IMR;								 
	volatile unsigned int ISR;			
	volatile unsigned int EDGE_SEL;  
}GPIO_Type;


/* 
 * 外设指针 
 */
#define CCM					((CCM_Type *)CCM_BASE)
#define CCM_ANALOG			((CCM_ANALOG_Type *)CCM_ANALOG_BASE)
#define IOMUX_SW_MUX		((IOMUX_SW_MUX_Type *)IOMUX_SW_MUX_BASE)
#define IOMUX_SW_PAD		((IOMUX_SW_PAD_Type *)IOMUX_SW_PAD_BASE)
#define GPIO1				((GPIO_Type *)GPIO1_BASE)
#define GPIO2				((GPIO_Type *)GPIO2_BASE)
#define GPIO3				((GPIO_Type *)GPIO3_BASE)
#define GPIO4				((GPIO_Type *)GPIO4_BASE)
#define GPIO5				((GPIO_Type *)GPIO5_BASE)

#endif // !_IMX6UL_H

? 3、修改驱动

main.c

#include "imx6ul.h"

/*
 * 使能时钟
*/
void clk_enable(void) 
{
    CCM->CCGR0 = 0xFFFFFFFF;
    CCM->CCGR1 = 0xFFFFFFFF;
    CCM->CCGR2 = 0xFFFFFFFF;
    CCM->CCGR3 = 0xFFFFFFFF;
    CCM->CCGR4 = 0xFFFFFFFF;
    CCM->CCGR5 = 0xFFFFFFFF;
    CCM->CCGR6 = 0xFFFFFFFF; 
}

/*
 * 使能时钟
*/
void led_init(void)
{
   /* 1、初始化IO复用 */
    IOMUX_SW_MUX->GPIO1_IO03 = 0x5;             /* 复用为GPIO1_IO03 */

    /* 2、配置GPIO1_IO03的IO属性	
	 *bit 16:0 HYS关闭
	 *bit [15:14]: 00 默认下拉
     *bit [13]: 0 kepper功能
     *bit [12]: 1 pull/keeper使能
     *bit [11]: 0 关闭开路输出
     *bit [7:6]: 10 速度100Mhz
     *bit [5:3]: 110 R0/6驱动能力
     *bit [0]: 0 低转换率
     */
    IOMUX_SW_PAD->GPIO1_IO03 = 0x10B;
    /* 3、初始化GPIO 第三位为输出 */
	GPIO1->GDIR =(1<<3);
    
    /* 4、设置GPIO1_IO03输出低电平，打开LED0 */	
    GPIO1->DR  &= ~(1<<3);
}


/*
 * @description	: 打开LED灯
 * @param 		: 无
 * @return 		: 无
 */
void led_on(void)
{
	/* 将GPIO1_DR的bit3清零 	*/
	GPIO1->DR &= ~(1<<3); 
}

/*
 * @description	: 关闭LED灯
 * @param 		: 无
 * @return 		: 无
 */
void led_off(void)
{
	/* 将GPIO1_DR的bit3置1 */
	GPIO1->DR |= (1<<3); 
}

/*
 * @description	: 短时间延时函数
 * @param - n	: 要延时循环次数(空操作循环次数，模式延时)
 * @return 		: 无
 */
void delay_short(volatile unsigned int n)
{
	while(n--){}
}

/*
 * @description	: 延时函数,在396Mhz的主频下
 * 			  	  延时时间大约为1ms
 * @param - n	: 要延时的ms数
 * @return 		: 无
 */
void delay(volatile unsigned int n)
{
	while(n--)
	{
		delay_short(0x7ff);
	}
}

/*
 * @description	: mian函数
 * @param 		: 无
 * @return 		: 无
 */
int main(void)
{
	clk_enable();		/* 使能所有的时钟 			*/
	led_init();			/* 初始化led 			*/

	while(1)			/* 死循环 				*/
	{	
		led_off();		/* 关闭LED 			*/
		delay(1000);		/* 延时500ms 			*/

		led_on();		/* 打开LED 			*/
		delay(1000);		/* 延时500ms 			*/
	}

	return 0;
}

三、编译下载验证

Makefile文件

OBJS    := main.o start.o
GCC     := arm-linux-gnueabihf-gcc
LD      := arm-linux-gnueabihf-ld 
OBJCOPY := arm-linux-gnueabihf-objcopy   
OBJDUMP := arm-linux-gnueabihf-objdump

led_stm32.bin : $(OBJS)
	$(LD) -Timx6ul.lds -o led.elf $^
	$(OBJCOPY) -O binary -S led.elf $@
	$(OBJDUMP) -D -m arm led.elf > led.dis
%.o : %.S
	$(GCC) -Wall -nostdlib -c -O2 -o $@ $<

%.o : %.c
	$(GCC) -Wall -nostdlib -c -O2 -o $@ $<

.PHONY clear:
	rm -rf *.o *.elf *.dis led_stm32.bin

编译下载

make

...

./imxdownload led_stm32.bin /dev/sdb

现象：

LED大约1s闪烁一次。

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