一，启动文件
.global _start
.global _bss_start /* 类似宏定义把__bss_start定义为_bss_start */
_bss_start:.word __bss_start.global _bss_end
_bss_end:.word __bss_end_start:#设置处理器进入SVC模式mrs r0, cpsr /* 读取cpsr到r0 */bic r0, r0, #0x1f /* 清除cpsr的bit4-0 */orr r0, r0, #0x13 /* 使用svc模式 */msr cpsr, r0 /* 将r0写入到cpsr */#清除BSS段,全置0ldr r0, _bss_startldr r1, _bss_endmov r2, #0 /* 向r2地址写0 */
bss_loop:stmia r0!, {r2} /* 把r2寄存器的值写入r0寄存器中，r0再自增4个字节 */cmp r0, r1 /* 比较r0和r1里的值 */ble bss_loop /* 如果r0地址小于等于r1,跳转到bss_loop中，继续清除bss段 */ldr sp, =0x80200000 /* 设置sp指针起始地址，此处已初始化ddr，若开发板未初始化ddr，则要手动初始化 */b main /* 跳转到C语言main函数 */二, main文件
采用结构体外交base基地址来访问外设
#include "imx6u.h"/* 使能外设时钟 */
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;
}void led_init(void)
{IOMUX_SW_MUX->GPIO1_IO03 = 0x5; /* 复用为GPIO1-IO03 */IOMUX_SW_PAD->GPIO1_IO03 = 0x10B0; /* 设置GPIO1_IO03电气属性 *//* GPIO初始化 */GPIO1->GDIR = 0x8; /* 设置为输出 */GPIO1->DR = 0x0; /* 打开LED灯 */
}/* 短延时 */
void delay_short(volatile unsigned int n)
{while(n--){}
}void delay(volatile unsigned int n)
{while(n--){delay_short(0x7ff);}
}/* 打开LED灯 */
void led_on(void)
{GPIO1->DR &= -(1<<3); /* bit3清零 */
}/* 关闭LED灯 */
void led_off(void)
{GPIO1->DR |= (1<<3) /* bit3置1 */
}int main(void)
{clk_enable(); /* 使能外设时钟 */led_init(); /* 初始化LED *//* 设置LED闪烁 */while(1){led_on();delay(500);led_off();delay(500);}return 0;
}#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)三，链接脚本文件
链接脚本文件中对地址操作时要进行四字节对齐，很重要
SECTIONS{. = 0X87800000;.text :{obj/start.o *(.text)}.rodata ALIGN(4) : {*(.rodata*)}.data ALIGN(4) : { *(.data) }. = ALIGN(4); #把_bass_start的地址四字节对齐，很重要__bss_start = . ; .bss ALIGN(4) : { *(.bss) *(COMMON) } __bss_end = . ;
}四，makefile文件
objs := start.o main.o
ld := arm-linux-gnueabihf-ld
gcc := arm-linux-gnueabihf-gcc
objcopy := arm-linux-gnueabihf-objcopy
objdump := arm-linux-gnueabihf-objdumpledc.bin : $(objs)$(ld) -Timx6u.lds -o ledc.elf $^$(objcopy) -O binary -S ledc.elf $@$(objdump) -D -m arm ledc.elf > ledc.dis%.0 : %.c$(gcc) -Wall -nostdlib -c -O2 -o $@ $<
%.0 : %.s$(gcc) -Wall -nostdlib -c -O2 -o $@ $<clean:rm -rf *.o ledc.bin ledc.elf ledc.dis
