硬件原理
从图可以看出，LED0 接到了 GPIO_3 上，GPIO_3 就是 GPIO1_IO03，当 GPIO1_IO03 输出低电平(0)的时候发光二极管 LED0 就会导通点亮，当 PIO1_IO03 输出高电平(1)的时候发 光二极管 LED0 不会导通，因此 LED0 也就不会点亮。所以 LED0 的亮灭取决于 GPIO1_IO03 的输出电平，输出 0 就亮，输出 1 就灭。
在虚拟机下创建strat.c main.h main.c makefile
1.汇编文件
start.s
.global _start
_start:
mrs r0, cpsr
bic r0, r0, #0x1f
orr r0, r0, #0x13
msr cpsr, r0
ldr sp, =0x80200000
b main
2.C语言文件
main.c
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)
{
SW_MUX_GPIO1_IO03 = 0x5;
SW_PAD_GPIO1_IO03 = 0x10B0;
GPIO1_GDIR = 0x0000008;
GPIO1_DR = 0X0;
}
void led_on(void)
{
GPIO1_DR &= ~(1<<3);
}
void led_off(void)
{
GPIO1_DR |= (1<<3);
}
void delay_short(volatile unsigned int n)
{
while(n--){}
}
void delay(volatile unsigned int n)
{
while(n--)
{
delay_short(0x7ff);
}
}
int main(void)
{
clk_enable();
led_init();
while(1)
{
led_off();
delay(500);
led_on();
delay(500);
}
return 0;
}
3.H头文件
main.h
#ifndef __MAIN_H
#define __MAIN_H
#define SW_MUX_GPIO1_IO03 *((volatile unsigned int *)0x020E0068)
#define SW_PAD_GPIO1_IO03 *((volatile unsigned int *)0x020E02F4)
#define GPIO1_DR *((volatile unsigned int *)0x0209C000)
#define GPIO1_GDIR *((volatile unsigned int *)0x0209C004)
#define GPIO1_PSR *((volatile unsigned int *)0x0209C008)
#define GPIO1_ICR1 *((volatile unsigned int *)0x0209C00C)
#define GPIO1_ICR2 *((volatile unsigned int *)0x0209C010)
#define GPIO1_IMR *((volatile unsigned int *)0x0209C014)
#define GPIO1_ISR *((volatile unsigned int *)0x0209C018)
#define GPIO1_EDGE_SEL *((volatile unsigned int *)0x0209C01C)
#endif
4.创建Makefile文件
makefile
objs := start.o main.o
ledc.bin : $(objs)
arm-linux-gnueabihf-ld -Ttext 0x87800000 $^ -o ledc.elf
arm-linux-gnueabihf-objcopy -O binary -S ledc.elf $@
arm-linux-gnueabihf-objdump -D -m arm ledc.elf > ledc.dis
%.o:%.c
arm-linux-gnueabihf-gcc -Wall -nostdlib -c -o $@ $<
%.o:%.s
arm-linux-gnueabihf-gcc -Wall -nostdlib -c -o $@ $<
clean:
rm -rf *.o ledc.bin ledc.elf ledc.dis
.global _start _start: mrs r0, cpsr bic r0, r0, #0x1f orr r0, r0, #0x13 msr cpsr, r0 ldr sp, =0x80200000 b main2.C语言文件 main.c
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)
{
SW_MUX_GPIO1_IO03 = 0x5;
SW_PAD_GPIO1_IO03 = 0x10B0;
GPIO1_GDIR = 0x0000008;
GPIO1_DR = 0X0;
}
void led_on(void)
{
GPIO1_DR &= ~(1<<3);
}
void led_off(void)
{
GPIO1_DR |= (1<<3);
}
void delay_short(volatile unsigned int n)
{
while(n--){}
}
void delay(volatile unsigned int n)
{
while(n--)
{
delay_short(0x7ff);
}
}
int main(void)
{
clk_enable();
led_init();
while(1)
{
led_off();
delay(500);
led_on();
delay(500);
}
return 0;
}
3.H头文件
main.h
#ifndef __MAIN_H #define __MAIN_H #define SW_MUX_GPIO1_IO03 *((volatile unsigned int *)0x020E0068) #define SW_PAD_GPIO1_IO03 *((volatile unsigned int *)0x020E02F4) #define GPIO1_DR *((volatile unsigned int *)0x0209C000) #define GPIO1_GDIR *((volatile unsigned int *)0x0209C004) #define GPIO1_PSR *((volatile unsigned int *)0x0209C008) #define GPIO1_ICR1 *((volatile unsigned int *)0x0209C00C) #define GPIO1_ICR2 *((volatile unsigned int *)0x0209C010) #define GPIO1_IMR *((volatile unsigned int *)0x0209C014) #define GPIO1_ISR *((volatile unsigned int *)0x0209C018) #define GPIO1_EDGE_SEL *((volatile unsigned int *)0x0209C01C) #endif4.创建Makefile文件 makefile
objs := start.o main.o ledc.bin : $(objs) arm-linux-gnueabihf-ld -Ttext 0x87800000 $^ -o ledc.elf arm-linux-gnueabihf-objcopy -O binary -S ledc.elf $@ arm-linux-gnueabihf-objdump -D -m arm ledc.elf > ledc.dis %.o:%.c arm-linux-gnueabihf-gcc -Wall -nostdlib -c -o $@ $< %.o:%.s arm-linux-gnueabihf-gcc -Wall -nostdlib -c -o $@ $< clean: rm -rf *.o ledc.bin ledc.elf ledc.dis
在终端中输入
make
调用makefile，生成.bin文件。
5.挂载SD卡将开发板SD卡装入读卡器连接到虚拟机之前，先用
ls /dev/sd*
命令查看当前虚拟机外接设备，当读卡机插入电脑，连接到虚拟机后，再用同样的命令查看，会得到SD卡插入位置。
6.代码烧写用imxdownload将文件烧写到SD卡中
将imxdownload文件复制到文件夹内，更改其权限。
chmod 777 imxdownload
烧写至SD卡
./imxdownload led.bin /dev/sdb
7.代码验证
设置开发板的拨码开关如下图，SD卡启动开发板方式，验证发光二极管效果
将SD卡插回开发板，可以看到LED灯闪烁效果。
LED灯闪烁
