0 basic self-study STM32 (wildfire) -- what is a register?

a key ：
Memory mapping
Register mapping

First, learn to distinguish the components 1 Pin No , Note counterclockwise rotation .
## First figure out the internal structure of the chip


“AHB, yes Advanced High performance Bus Abbreviation , Advanced high performance bus ;
APB, yes Advanced Peripheral Bus Abbreviation , Advanced peripheral bus .”

Drive unit ：



Passive unit ：





Next, check out the official data book （ English version ）

ARM The kernel is 32 position , That's it 2 Of 32 Power , That is to say 4294967296byte（ byte ）,1kb=1024byte, That is, that is 4194304kB,1mb =1024kb, That is to say 4096mb, and 1gb=1024mb , In the end is 4gb
therefore arm The kernel can access 4gb Content ,arm Then we will 4g The memory is divided into eight blocks .

512mb*8=4096mb=4g

flash It's in the first piece

We can see from the external package of the chip that the chip used by wildfire is stm32f103zet6
Among them e On behalf of 512k Of flash

Obviously, only a small part is used

The point is block2 Peripheral part

Memory mapping （ a key ）
What is memory mapping ？
The memory itself does not have address information , His address is assigned by the game film manufacturer or user , The process of assigning addresses to memory is memory mapping

Register mapping
With stc51 For example

# include <stdio.h>

sbit  LED = P0^0;

void main (void)
{
    
	P0 = 0xfe;
	LED =0;

}

Pay attention to the... We use P0, It is contained in the header file , The header file uses sfr Keyword let P0 Corresponding to the address of the corresponding register .

And in the stm32 Middle yield GPIOB Port of 16 Pin outputs high level , How to do that ？？
Access memory units through absolute addresses
//GPIOB All ports output High level

*（unsigned int*）(0x40010C0C) = 0xFFFF;

We find GPIOB Register start address of


We see the ODR The address offset of ：0x0C, The offset here is the offset from the base address of the register just found . because GPIOB There is more than one register for .
that GPIOB The address of the port is ：GPIOB The base address + Address offset
We can be right IO To operate

*（unsigned int*）(0x40010C0C) = 0xFFFF;

among 0x40010C0C Is the address of the register
For the above, we need to grasp several key points ：
1：0x40010C0C As GPIOB Output data register ODR How do people find your address ？
2：（unsigned int） What is the role of ？
3： Learn how to use c Linguistic “*” Number *

*（unsigned int*）(0x40010C0C) = 0xFFFF;

Let's first cast 0x40010C0C As address .
If we write it directly as 0x40010C0C = 0xFFFF; The compiler doesn't know 0x40010C0C It's the address , So I can't use it . We need to force conversion .

Obviously, the above method is troublesome .

Access memory unit by register alias ：

//GPIOB All ports output high level 
# define GPIOB_ODR （unsigned int*）(0x40010C0C) ;
* GPIOB_ODR = 0xFF;

For the convenience of operation, you can also “*” Also defined in the alias of the register

//GPIOB All ports output high level 
# define GPIOB_ODR *（unsigned int*）(0x40010C0C) ;
GPIOB_ODR = 0xFF;