STM32 timer interrupt learning notes

stay stm32 in , Timer related library functions mainly focus on firmware library files stm32f10x_tim.h and stm32f10x_tim.c In file , So when processing the timer , You need to load these two files .

During timer operation , Generally, the following steps are followed ：

 1、 Turn on the clock of the relevant peripheral .

     With a timer TIM3 For example , from stm32 The clock tree can be seen ,TIM3 The clock is connected to APB1 above , So open TIM3 Clock time use RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3,ENABLE), If other peripherals are used , Such as GPIO etc. , Turn on the relevant peripheral clock .

 2、 Clear the interrupt hold bit .

     Due to various unknowable factors , The interrupt pending bit of the timer to be operated before the program runs may be set , This will cause the interrupt service program to enter the timer interrupt at the beginning of the program . To eliminate this effect , We clear the interrupt hold bit at the beginning of the program .

Use... In the firmware library ：

void TIM_ClearITPendingBit(TIM_TypeDef*TIMx, u16 TIM_IT)

To clear the interrupt hold bit , Refer to the firmware library manual for the specific use of this function .

3、 Timer basic configuration initialization .

     In this step, it mainly determines the pre frequency division of the timer and sets the value of the automatic reload register cycle , And determine the counting mode , This mainly uses... In the firmware library TIM_TimeBaseInit() Function to operate , The prototype of this function is ：

void TIM_TimeBaseInit(TIM_TypeDef* TIMx,TIM_TimeBaseInitTypeDef* TIM_TimeBaseInitStruct)

The first input parameter has nothing to say , Which timer is used .

typedef struct  
{  
<span style="white-space:pre;"> </span>u16 TIM_Period;//  The value of the automatic reload register cycle   
<span style="white-space:pre;"> </span>u16 TIM_Prescaler;// Prescaled value   
<span style="white-space:pre;"> </span>u8 TIM_ClockDivision;// Partition coefficient , Generally set as 0, Do not divide   
<span style="white-space:pre;"> </span>u16 TIM_CounterMode;// Count mode   
} TIM_TimeBaseInitTypeDef; 

4、 Enable timer TIMx.

     This simple , Direct functions TIM_Cmd() Function is OK , Such as enable timer TIM3 peripherals , Available TIM_Cmd(TIM3,ENABLE).

5、 Can make TIMx interrupt . 

     Just call the function . Because we need to use TIM3 The update of , The corresponding bit of the register enables the update interrupt . In the library function, timer interrupt is enabled by TIM_ITConfig Function to implement ：

void TIM_ITConfig(TIM_TypeDef* TIMx, uint16_t TIM_IT, FunctionalState NewState);

The first parameter is the timer , This is easy to understand , The value is TIM1~TIM17.

The second parameter is critical , Is used to indicate the type of timer interrupt that we enable , Timer interrupt .

There are many types , Including update interrupt TIM_IT_Update, Trigger interrupt TIM_IT_Trigger, And input capture interrupt and so on .

The third parameter is very simple , Is it disabled or enabled .

For example, we need to enable TIM3 The update of , The format is ：TIM_ITConfig(TIM3,TIM_IT_Update,ENABLE );

6、 Configure interrupt priority .

     That is, configure nested vector terminal controllers NVIC. To perform this step, you first need to configure the priority grouping , You can use library functions NVIC_PriorityGroupConfig() Conduct , The number of the group is the number of bits of preemptive priority , Then configure NVIC initialization , Using functions NVIC_Init() Conduct , The prototype of this function is void NVIC_Init(NVIC_InitTypeDef* NVIC_InitStruct), The structure of input parameters is defined as follows ：

typedef struct  
{  
<span style="white-space:pre;"> </span>u8 NVIC_IRQChannel; // Interrupt channel   
<span style="white-space:pre;"> </span>u8 NVIC_IRQChannelPreemptionPriority;// preemption   
<span style="white-space:pre;"> </span>u8 NVIC_IRQChannelSubPriority;// Response priority   
<span style="white-space:pre;"> </span>FunctionalState NVIC_IRQChannelCmd;//  Specify in the member  NVIC_IRQChannel  As defined in  IRQ  Is the channel enabled or disabled   
} NVIC_InitTypeDef;  

7、 Write interrupt service program . ad locum , We first need to clear the interrupt hold bit , This function is the same as that in Chapter 2 In step , There is no need to repeat , Then write the interrupt processing content .

The complete timer interrupt initialization procedure is as follows , This program is the contents of timer interrupt in the CD provided by Puzhong technology .

void timeInit()  
{  
TIM_TimeBaseInitTypeDef TIM_TimeBaseInitStructure; // Declare a structure variable , Used to initialize  GPIO  
NVIC_InitTypeDef NVIC_InitStructure;  
/*  Turn on timer  3  The clock  */  
RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3,ENABLE);  
TIM_ClearITPendingBit(TIM3,TIM_IT_Update);// eliminate  TIMx  Interrupt pending bit of :TIM  Interrupt source   
TIM_TimeBaseInitStructure.TIM_Period = 2000;// Set the value of the automatic reload register cycle   
TIM_TimeBaseInitStructure.TIM_Prescaler = 35999;// Set as  TIMx Clock frequency prescaled value ,100Khz  Counting frequency   
TIM_TimeBaseInitStructure.TIM_ClockDivision = 0; // Set the clock split :TDTS = Tck_tim  
TIM_TimeBaseInitStructure.TIM_CounterMode =TIM_CounterMode_Up;//TIM  Upcount mode   
TIM_TimeBaseInit(TIM3,&TIM_TimeBaseInitStructure);  
TIM_Cmd(TIM3,ENABLE); // To enable or disable  TIMx  peripherals   

/

/*  Set interrupt parameters , And turn on the interrupt  */  
TIM_ITConfig(TIM3, TIM_IT_Update, ENABLE ); // To enable or disable specified TIM  interrupt   
/*  Set up  NVIC  Parameters  */  
NVIC_PriorityGroupConfig(NVIC_PriorityGroup_1);  
NVIC_InitStructure.NVIC_IRQChannel=TIM3_IRQn; // open  TIM3_IRQn  Global interrupt   
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority=0;// Preemption priority is  0  
NVIC_InitStructure.NVIC_IRQChannelSubPriority=1; // The response priority is  1  
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE; // Can make   
NVIC_Init(&NVIC_InitStructure);  
}