Day 1 of the 10 day smart lock project (understand the SCM stm32f401ret6 and C language foundation)

One 、 Learning goals

Two 、 Understand SCM STM32F401RET6

4、STM32F401RE features

3、 ... and 、C Language foundation

1. data type
Commonly used 2 To the power of ：

2^7 = 128
2^8 = 256
2^15 = 32768
2^16= 65536
51 Common data types of single chip microcomputer ：
char: Occupy memory 1 byte Value range ：-128~127 -2^7 ~ 2^7-1
unsigned char: 0~255
int: Occupy memory 4 byte Value range ：-32768~32767
unsigned int: 0~65535
long int : Occupy memory 4 byte Value range ：-2147483648~2147483647
unsigned long int:0~4294967295

Add ：1 byte （byte） = 8 position （bit） Every representative 0/1

2. Hexadecimal conversion
① Convert decimal to binary
Eg：83

② 16 Binary to binary
Eg：0XFF
16 Base number ： 0 1 2 3 4 5 6 7 8 9 A B C D E Ff:1 2 4 8

3. Variable

Before using variables, users need to define variables
Defining variables ：
Int a; //a yes int Variable of type
char b;//b yes char Type variables
float c;//c yes float Type variables

Special prefix ：
extern int a;// Statement int Variable of type a, Can be used across files , commonly .h It is defined
const int b=1;// Define an immutable variable , Use const Keyword should be given an initial value
static int c=1;// Static variables , Initialize only when first used , Equivalent to a global variable

4. Basic statement

Conditional statements ：
If(a>0)
{
perform ;
}
Else、else if

remind ：
If When judging the results of the following conditional statements , Non zero is true , Zero is false
Else There is no need to add a condition later

switch(ch)
{
case ‘a’: perform ; break;
case ‘b’: perform ; break;
}

Loop statement ：
for
Format ：
for(i=0;i<n;i++)
{

}

While
Format ：
while(1)
{
;
}
do while;// It is applicable to the cycle without knowing the number of cycles

Control statement ：
break;// Jump out of conditional statements and loop statements directly
coutinue;
goto