ARMday06(串口)

代码：

#include "gpio.h"
#include "stm32mp1xx_gpio.h"
#include "stm32mp1xx_rcc.h"
#include "stm32mp1xx_uart.h"
void init();
char getc();
void putc(const char data);
int main()
{
	init();//初始化
	putc('j');
	char c=getc();
	putc(c);

	while(1);
	return 0;
}
void init(){

	//设置使能
	RCC->MP_AHB4ENSETR|=(0x1<<1);
	RCC->MP_AHB4ENSETR|=(0x1<<6);
	
	RCC->MP_APB1ENSETR|=(0X1<<16);

	//设置PG11和PB2功能复用为UART4功能
    //PG11
    //GPIOG_MODER[23:22]->10
    GPIOG->MODER &= (~(0X3<<22));
    GPIOG->MODER |= (0X2<<22);
    //GPIOG_AFRH[15:12]->0110    
    GPIOG->AFRH &= (~(0xf<<12));
    GPIOG->AFRH |= (0x6<<12);
    //PB2
    //GPIOB_MODER[5:4]->10
    //GPIOB_AFRL[11:8]->1000
    GPIOB->MODER &= (~(0x3<<4));
    GPIOB->MODER |= (0X2<<4);
    GPIOB->AFRL &= (~(0xF<<8));
    GPIOB->AFRL |= (0x8<<8);
    //禁用串口
    USART4->CR1 &=(~0x1);
    //设置数据8个数据位 CR1[28]->0  CR1[12]-》0
    USART4->CR1 &= (~(0X1<<28));
    USART4->CR1 &= (~(0X1<<12));
    //设置没有校验位CR1[10]->0
    USART4->CR1 &= (~(0X1<<10));
    //设置1个停止位CR2[13:12]->00
    USART4->CR2 &= (~(0x3<<12));
    //设置16倍采样 CR1[15]->0
    USART4->CR1 &= (~(0X1<<15));
    //设置波特率为115200 BRR=0X22B
    USART4->BRR |= 0X22B;
    //设置1分频 PRESC[3:0]->0000
    USART4->PRESC &= (~(0XF));
    //使能发送器 CR1[3]->1
    USART4->CR1 |= (0X1<<3);
    //使能接收器 CR1[2]->1
    USART4->CR1 |= (0X1<<2);
    //使能串口 CR1[0]->1
    USART4->CR1 |= (0X1);

}
void putc(const char data)
{
//判断发送数据寄存器有没有数据，没有数据时可以发送
    while(!(USART4->ISR&(0X1<<7)));
    USART4->TDR=data;//将要发送的数据保存在发送寄存器中
    while(!(USART4->ISR&(0X1<<6)));//数据传输完成，函数结束
}
char getc(void)
{
	char ch;
	while(!(USART4->ISR & (0x1 << 5)));
	ch = (char)USART4->RDR;
	return ch;
}

what a pity,can't run