0 basic self-study STM32 (wildfire) - register lit LED

Wildfire register on LED

#if 0

# include<stdio.h>
sbit LED = P0^0;
	void main (void)
{
    
		//P0 = 0xFE; // Bus operation 
		LED = 0;      // Bit operation 
}

#endif

# include "stm32f10x.h"
void SystemInit(void);
int main (void)
{
    
	// Clock control 
	*(unsigned int*)0x40021018 |=(1<<(3));	// open GPIOB Port clock 
	// The output mode 
	*(unsigned int*)0x40010C00 |=(1<<(4*0));	//CRL Port configuration register , Push pull output 
	// Data settings 
	*(unsigned int*)0x40010C0C &=~(unsigned int)(1<<0);  //ODR Data output register . Register operation   In combination with the schematic diagram, this step is to light up 
	//*(unsigned int*)0x40010C0C |=(1<<0); // In combination with the schematic diagram, this step is to extinguish 

	
	//*(unsigned int*)0x40010C0C &=~(1<<0);// The code in the video is not forcibly converted to (unsigned int)(1<<0) Write it like this , I write this because the video source code generates a warning after compilation , It suggests that we are going to int The value to unsigned int Type of 
	
}


//|=
//&=~
void SystemInit(void)
{
    
	
}

//  For storage STM32 Register mapping code 

//  peripherals  perirhral

#define  PERIPH_BASE               ((unsigned int)0x40000000)	// Peripheral base address 
#define  APB1PERIPH_BASE           PERIPH_BASE                //APB1 Bus base address 
#define  APB2PERIPH_BASE          (PERIPH_BASE + 0x10000)     //APB2 Bus address 
#define  AHBPERIPH_BASE           (PERIPH_BASE + 0x20000)			//AHB Bus address 


#define  RCC_BASE                (AHBPERIPH_BASE + 0x1000)		// Clock bus 
#define  GPIOB_BASE              (APB2PERIPH_BASE + 0x0C00)   //GPIOB Bus 


#define  RCC_APB2ENR            *(unsigned int*)(RCC_BASE + 0x18)	// Clock enable register 
	
#define  GPIOB_CRL              *(unsigned int*)(GPIOB_BASE + 0x00)  // Port configuration low register 
#define  GPIOB_CRH              *(unsigned int*)(GPIOB_BASE + 0x04)  // Port configuration high register 
#define  GPIOB_ODR              *(unsigned int*)(GPIOB_BASE + 0x0C)		// Port output data register 

	

What we do is PB0

Notice that there's a BUG, our ODR The initial value of the register after reset is 0x0000 0000
This is equivalent to saying ODR0 Also reset to 0. Even if we block what we wrote above ODR&=~（1<<0） This line of code ,LED Still lit . So try to avoid the impact of this reset operation .

Here's another point . That is the order of register configuration , Configure the clock first , Reconfigure input / Output , Then give the data . Otherwise, it is possible to GPIO There is no output .