Getting started stm32--gpio (running lantern) (nanny level)

Catalog

Preface

One 、GPIO What is it? ？

Two 、GPIO What for?

3、 ... and 、GPIO How to do it

3、 ... and 、 How to use GPIO Light up a LED The lamp

        1.  GPIO_InitTypeDef 

2.GPIO_Init   

3.RCC_APB2PeriphClockCmd

Four 、 initialization

5、 ... and 、 synthesis

Time delay

The header file

initialization

6、 ... and 、 Two lights

---

Preface

This is also a relatively simple part , Let's officially start our 32 The way .

typedef 

Structure  

enumeration  

These are the basics , If you want to understand the program , Understanding can . 

One 、GPIO What is it? ？

All embedded processors have integrated general input and output （General Purpose Input Output,GPIO) Interface , Generally speaking , In fact, it is the pin on your development version , That thing is on your SCM IO mouth （GPIO） It's connected （ It's easy to connect , Easy to develop ）. STM32 Of IO The mouth is divided into several groups ,PA、PB、PC etc. , Each group has 16 A pin ,PA0、PA1、PA2、PA3 wait .

Two 、GPIO What for?

from Output Input These two words can also be seen , He does input and output .

Our single-chip microcomputer is generally the main control , To control other circuits or motors , Since it is control, it must output control signals , So we need IO mouth , To do the output . Again , SCM certainly also needs external information , So input function is also required .

  The most basic output function is made up of STM32 Control pin output high 、 Low level , Switch control is realized , If you put GPIO Pin into LED The lamp , Then you can control LED The light goes on and off , Pin into relay or triode , Then you can control the on-off of external high-power circuits through relays or triodes .

3、 ... and 、GPIO How to do it

To put it simply , This diagram can be divided into two parts , It's the input , Here is the output .

Look from right to left , First the pin, then the protective diode （ The function is to protect your pin from being compared 3V3 It could be 5V Higher , Or 0V Lower voltage damage , But remember one thing ）, Let's move on to two parts .

The input part is , After entering, pull up or pull down the resistance , And then there was TTL Schottky trigger （TTL Schottky trigger can be understood as Schmidt trigger composed of Schottky tube , The function is simply to turn the relatively slow changing analog signal into a rectangular signal , Easy to read later .） Then it can be read .

Output part , Is a MOS The conduction and disconnection of the tube control the output level . You can see , When the highest level is output VDD（ Working voltage of single chip microcomputer ,2.0~3.6V, It's usually 3.3V）, The lowest level is Vss（ SCM power supply ground ,0V）.

3、 ... and 、 How to use GPIO Light up a LED The lamp

  without doubt , We definitely need to write code , Through the code we wrote , Tell SCM what we want to do .

If the function we choose is input , Then what we need is to read the relevant registers （ It can be understood as a memory , We can write numbers inside , You can control SCM . Again , Some data of the single chip microcomputer is also stored here .） Value , You can get relevant IO The level of the port , If we choose output , What we need to do is control MOS Turn on and off the tube .

The first thing we need to do is determine what we want to use IO mouth , We should look for the schematic , And then find LED The pin corresponding to the lamp .

 

We can see ,LED0 The corresponding is PB5 This pin , The next thing to do is to write a program . 

1.  GPIO_InitTypeDef 

  First , We're going to define a structure , It's mentioned above , We control the SCM by writing numbers into the register , Registers are converted into programs and divided into many structures , We need to write numbers in it , Also through the way of structure .

 GPIO_InitTypeDef  GPIO_InitStructure;

  This  GPIO_InitTypeDef It's through typedef Get a macro definition , It is convenient to use it to define variables and GPIO The register type structure conforms to the structure . The one in the back GPIO_InitStructure Is the structure we define （ Random names , This is what I call it when I study ）.

typedef struct
{
  uint16_t GPIO_Pin;             /*!< Specifies the GPIO pins to be configured.
                                      This parameter can be any value of @ref GPIO_pins_define */

  GPIOSpeed_TypeDef GPIO_Speed;  /*!< Specifies the speed for the selected pins.
                                      This parameter can be a value of @ref GPIOSpeed_TypeDef */

  GPIOMode_TypeDef GPIO_Mode;    /*!< Specifies the operating mode for the selected pins.
                                      This parameter can be a value of @ref GPIOMode_TypeDef */
}GPIO_InitTypeDef;

Now let's analyze the members in this structure ,

1. GPIO_Pin It means Which pin , for example GPIO_Pin_5, It stands for PX5 This pin , among X=A、B、C、D etc. .

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_5;

2.GPIOSpeed_TypeDef GPIO_Speed, Here is an enumeration definition , The preceding is the type of enumeration , Followed by the name of the enumeration .

GPIO Pin speed ： GPIO_Speed_2MHz     (10MHz, 50MHz) ;

Also known as the response speed of the output drive circuit ：（ Inside the chip is I/O The output part of the port is arranged with a number of output driving circuits with different response speed , Users can choose the right driving circuit according to their own needs , Select different output driver modules by selecting speed , Achieve the best noise control and reduce power consumption .）

The simple understanding is ,IO Response speed of mouth .

GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;

typedef enum
{ 
  GPIO_Speed_10MHz = 1,
  GPIO_Speed_2MHz, 
  GPIO_Speed_50MHz
}GPIOSpeed_TypeDef;

 3.GPIOMode_TypeDef GPIO_Mode Obvious , Here is another definition of enumeration , The front is the type , Followed by the name .

typedef enum
{ GPIO_Mode_AIN = 0x0,
  GPIO_Mode_IN_FLOATING = 0x04,
  GPIO_Mode_IPD = 0x28,
  GPIO_Mode_IPU = 0x48,
  GPIO_Mode_Out_OD = 0x14,
  GPIO_Mode_Out_PP = 0x10,
  GPIO_Mode_AF_OD = 0x1C,
  GPIO_Mode_AF_PP = 0x18
}GPIOMode_TypeDef;

There are different modes , If we choose output ,GPIO_Mode_Out_PP That's what we want , It is called push-pull output , There are many other ways , I won't go into details , You can refer to other articles .

GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;

2.GPIO_Init   

After we configure the above structure members , We have finished most of , But it's not over , You'll find that , We just determine the value in the structure of our definition , It is not put into the register of the single chip microcomputer , Certainly not at this time .

How to put it in , Others thought of this in , Call the function directly .

​

GPIO_Init(GPIOB, &GPIO_InitStructure); 

  You can see , This function needs to input two parameters , One is A、B、C、D etc. , Determine which set of pins we want to control .

Another parameter is the address of the structure we define .

For example , The structure we define is better than a package , This function is the courier , What we want to tell you is which express we send , To where .

You may feel almost here , In fact, there is no . Are we going to tell the person who receives the express , You have express delivery , How to tell , A function is OK 了 .

3.RCC_APB2PeriphClockCmd

​

RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB, ENABLE);   

  You can see , This function also has two arguments , The first parameter is the clock of which group of pins is enabled , The second pin is enable （ENABLE）.
The reason why the peripheral clock is enabled https://blog.csdn.net/weixin_43217963/article/details/97792677 Be careful ： Be sure to enable PB The clock of the port is then configured GPIO

void GPIO_Init(void)
{
 
 GPIO_InitTypeDef  GPIO_InitStructure;
 	
 RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB, ENABLE);	 // Can make PB Port clock 
	
 GPIO_InitStructure.GPIO_Pin = GPIO_Pin_5;				 //PB.5  port configuration 
 GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP; 		 // Push pull output 
 GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;		 //IO The mouth speed is 50MHz
 GPIO_Init(GPIOB, &GPIO_InitStructure);					 // Initialize according to the set parameters GPIOB.5
 GPIO_SetBits(GPIOB,GPIO_Pin_5);						 //PB.5  High output 
}

Four 、 initialization

Initialization is an important problem , Many novices have written the function after experiencing all kinds of difficulties and dangers , Get the program in , I found the light doesn't work .BBQ 了 , Most of the reasons are initialization .

  Maybe many novices have created a new file LED, There are led.c and led.h These two documents , Put the function written by yourself into led.c Inside the , It's ok , But there is no need , I still suggest writing directly main.c In this document , After all, we're just lighting a light .

Just like this

 

  Although not written led.c It's simple inside , But initialization will be much more convenient （ Avoid many pits ）.

If you have to create a file , Be sure to remember in led.h It says ,main.c The file should include relevant header files .

5、 ... and 、 synthesis

Put together what we wrote before , Like this

  But you will find , The light is always on , This is because the execution speed of MCU is very fast , The setting of high and low levels is completed in an instant , Human eyes can't react .

So you need a delay function , Just let the light come on later , Also wait for a while .

Time delay

There are two ways to delay , The first is that we can call the delay function directly （ Functions written by others ）, You can also write a cycle to delay .

Let's just use the first one , All you need to do is include the corresponding header file , And initialization delay function .

The header file

Just include it directly in the main function

  initialization

add a sentence delay_init(); that will do

delay_ms(200); It's a delay 200 millisecond

delay_ms(500); It's a delay 500 millisecond

Be careful ： The single delay time cannot exceed 1864ms

Add the delay function

The light flashed ~~~

6、 ... and 、 Two lights

Just like this.

 

  Give a brief explanation , First, there is one more port clock PE Of , You can use a function directly , But notice one or Steps for .

The second place is , In the configuration PE5 when , The last structure is still used . Because the second lamp is also pin 5 , No other changes are required .

The third place is the main function , It's easy here, too , Just two more sentences .