GPIO端口初始化
1.时钟配置
本次实验采用GPIOA、B、C三个端口。该三个端口都属于APB2总线
输入输出模式和输出速率设置
本次实验采用通用推挽输出模式，最高输出时钟频率2Mhz。分别用到PA7、PB9、C15三个引脚。其中PA7、PB9属于端口配置低寄存器偏移地址为0x00，C13属于端口配置高寄存器偏移地址为0x04。
代码实现：
C语言：
//--------------APB2使能时钟寄存器------------------------
#define RCC_AP2ENR *((unsigned volatile int*)0x40021018)
//----------------GPIOA配置寄存器 ------------------------
#define GPIOA_CRL *((unsigned volatile int*)0x40010800)
#define GPIOA_ORD *((unsigned volatile int*)0x4001080C)
//----------------GPIOB配置寄存器 ------------------------
#define GPIOB_CRH *((unsigned volatile int*)0x40010C04)
#define GPIOB_ORD *((unsigned volatile int*)0x40010C0C)
//----------------GPIOC配置寄存器 ------------------------
#define GPIOC_CRH *((unsigned volatile int*)0x40011004)
#define GPIOC_ORD *((unsigned volatile int*)0x4001100C)
//-------------------简单的延时函数-----------------------
void Delay_ms( volatile unsigned int t)
{
unsigned int i;
while(t--)
for (i=0;i<800;i++);
}
void A_LED_LIGHT(){
GPIOA_ORD=0x0<<7; //PA7低电平
GPIOB_ORD=0x1<<9; //PB9高电平
GPIOC_ORD=0x1<<15; //PC15高电平
}
void B_LED_LIGHT(){
GPIOA_ORD=0x1<<7; //PA7高电平
GPIOB_ORD=0x0<<9; //PB9低电平
GPIOC_ORD=0x1<<15; //PC15高电平
}
void C_LED_LIGHT(){
GPIOA_ORD=0x1<<7; //PA7高电平
GPIOB_ORD=0x1<<9; //PB9高电平
GPIOC_ORD=0x0<<15; //PC15低电平
}
//------------------------主函数--------------------------
int main()
{
int j=100;
RCC_AP2ENR|=1<<2; //APB2-GPIOA外设时钟使能
RCC_AP2ENR|=1<<3; //APB2-GPIOB外设时钟使能
RCC_AP2ENR|=1<<4; //APB2-GPIOC外设时钟使能
//这两行代码可以合为 RCC_APB2ENR|=1<<3|1<<4;
GPIOA_CRL&=0x0FFFFFFF; //设置位 清零
GPIOA_CRL|=0x20000000; //PA7推挽输出
GPIOA_ORD|=1<<7; //设置PA7初始灯为灭
GPIOB_CRH&=0xFFFFFF0F; //设置位 清零
GPIOB_CRH|=0x00000020; //PB9推挽输出
GPIOB_ORD|=1<<9; //设置初始灯为灭
GPIOC_CRH&=0x0FFFFFFF; //设置位 清零
GPIOC_CRH|=0x30000000; //PC15推挽输出
GPIOC_ORD|=0x1<<15; //设置初始灯为灭
while(j)
{
A_LED_LIGHT();
Delay_ms(10000000);
B_LED_LIGHT();
Delay_ms(10000000);
C_LED_LIGHT();
Delay_ms(10000000);
}
}
汇编语言：
AREA MYDATA, DATA
AREA MYCODE, CODE
ENTRY
EXPORT led
led
;使能A,B,C
ldr r0, =0x40021018
ldr r1, =0x0000001c
str r1, [r0]
;配置端口PA7
ldr r0, =0x4001080C
ldr r1, [r0]
bic r1, r1, #0x000f0000
orr r1, r1, #0x00010000
str r1, [r0]
;配置端口PB8
ldr r0, =0x40010c00
ldr r1, [r0]
bic r1, r1, #0x00f00000
orr r1, r1, #0x00100000
str r1, [r0]
;配置端口PC15
ldr r0, =0x40011004
ldr r1, [r0]
bic r1, r1, #0x0f000000
orr r1, r1, #0x01000000
str r1, [r0]
;初始为A4亮灯
ldr r0, =0x4001080c
ldr r1, =0x00000010
str r1, [r0]
ldr r0, =5000000;频率
ldr r1, =0
；循环亮灯
blink
add r1, r1, #1
cmp r1, r0
blt blink
;A4灭
ldr r1, =0x4001080c
ldr r2, [r1]
eor r2, r2, #0x00000010
str r2, [r1]
;B5亮
ldr r1, =0x40010c0c
ldr r2, [r1]
eor r2, r2, #0x00000020
str r2, [r1]
ldr r1, =0
blink1
add r1, r1, #1
cmp r1, r0
blt blink1
;B5灭
ldr r1, =0x40010c0c
ldr r2, [r1]
eor r2, r2, #0x00000020
str r2, [r1]
;C14亮
ldr r1, =0x4001100c
ldr r2, [r1]
eor r2, r2, #0x00004000
str r2, [r1]
ldr r1, =0
blink2
add r1, r1, #1
cmp r1, r0
blt blink2
;C14灭
ldr r1, =0x4001100c
ldr r2, [r1]
eor r2, r2, #0x00004000
str r2, [r1]
;A4亮
ldr r1, =0x4001080c
ldr r2, [r1]
eor r2, r2, #0x00000010
str r2, [r1]
ldr r1, =0
b blink
END
效果
总结：
GPIO端口的初始化设置还不够熟悉，接线还是比较简单，寄存器映射原理不够熟悉。
参考链接：
https://blog.csdn.net/daniaoxp/article/details/100176967
https://blog.csdn.net/geek_monkey/article/details/86291377
https://blog.csdn.net/geek_monkey/article/details/86293880