Timer interrupt experiment

Catalog

One 、 What is? TIM

1.TIM Definition

2. Timer classification ：

Two 、 Configuration of timer interrupt

1. Configuration process of timer interrupt ：

2. According to the routine

  3、 ... and .TIM Introduction to library functions

Four , Using variables across files

5、 ... and . A problem about timer interrupt experiment

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One 、 What is? TIM

1.TIM Definition

TIM(Timer) Timer : The timer can count the input clock , And trigger the interrupt when the count value reaches the set value

TIM The timer not only has the basic timing interrupt function , It also includes the selection of internal and external clock sources , Input capture , Output comparison , Encoder interface , Master slave trigger mode and other functions .

2. Timer classification ：

type	Number	Bus	function
Advanced timer	TIM1,TIM8	APB2	It has all functions of general timer , And additionally, it has a repetition counter , Dead zone generation , Complementary output , Brake input and other functions
Universal timer	TIM2,TIM3,TIM4,TIM5	APB1	Have all functions of basic timer , In addition, it has internal and external clock source selection , Input capture , Output comparison , Encoder interface , Master slave trigger mode and other functions
Basic timer	TIM6,TIM7	APB1	Have timed interrupts , The main mode triggers DAC The function of

Two 、 Configuration of timer interrupt

1. Configuration process of timer interrupt ：

First step , Turn on RCC The clock . Turn on the clock here , The reference clock of the timer and the working clock of the whole peripheral will be turned on at the same time
The second step , Select the clock source of the time base unit , For timed interrupts , We choose the internal clock source
The third step , Configure the time base unit , Including prescaler , Automatic reassembler , Counting mode, etc
Step four , Configure output interrupt control , Allow update interrupt output to NVIC
Step five , To configure NVIC, stay NVIC Open the channel interrupted by the timer , And assign a priority
Step six , Operation control , After the configuration of the whole module is completed , Enable the counter , Otherwise, the counter will not run

2. According to the routine

Timer.c

#include "stm32f10x.h"                  // Device header

//extern uint16_t Num;
void Timer_Init(void)
{
	RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);// First step 
	TIM_InternalClockConfig(TIM2); // The second step , You can choose an internal clock without writing , Because after the timer is powered on, the default is the internal clock 
	
	TIM_TimeBaseInitTypeDef TIM_TimeBaseInitStructure;
	TIM_TimeBaseInitStructure.TIM_ClockDivision = TIM_CKD_DIV1;
	TIM_TimeBaseInitStructure.TIM_CounterMode = TIM_CounterMode_Up;
	TIM_TimeBaseInitStructure.TIM_Period = 10000-1; // cycle , Namely ARR The value of the automatic reloader 
	TIM_TimeBaseInitStructure.TIM_Prescaler = 7200-1;//PSC Prescaler value , Prescaler and counter have 1 Number deviation 
	// At this time, the prescaler is 72M Conduct 7200 Frequency division of the system , What you get is 10K The counting frequency of , stay 10K At different frequencies , meter 10000 Number , That is to say 1s
	// Realize the calculation of timing time 
	
	TIM_TimeBaseInitStructure.TIM_RepetitionCounter =0;// Repeat counter value , This advanced timer is only used , Let's give it directly to 0
	TIM_TimeBaseInit(TIM2,&TIM_TimeBaseInitStructure);
	// Come here , The time base unit is configured , Next, enable the update interrupt 
	
	TIM_ClearFlag(TIM2,TIM_FLAG_Update);// It solves the problem of interruption immediately after power on 
	
	TIM_ITConfig(TIM2,TIM_IT_Update,ENABLE);// To interrupt 
	// This enables the update interrupt to NVIC Access to 
	NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2);// Priority groups 
	NVIC_InitTypeDef NVIC_InitStructure;
	NVIC_InitStructure.NVIC_IRQChannel = TIM2_IRQn;
	NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
	NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 2;// preemption 
	NVIC_InitStructure.NVIC_IRQChannelSubPriority = 1;// Response priority 
	NVIC_Init(&NVIC_InitStructure);
	// At this time, the interrupt channel is opened 

	TIM_Cmd(TIM2,ENABLE);
	// So the timer can work 
}

main.c

#include "stm32f10x.h"                  // Device header
#include "OLED.h"
#include "Timer.h"


uint16_t Num;

int main(void)
{
	OLED_Init();
	Timer_Init();
	OLED_ShowString(1, 1, "Num:");

	while(1)
	{
		
		
		 
		OLED_ShowNum(1,5,Num,5);		
		OLED_ShowNum(2,5,TIM_GetCounter(TIM2),5);//CNT Change of counter value  （ from 0 To auto reload value , That's what we set up 10000-1）
	}
}

void  TIM2_IRQHandler(void)
{
	if(TIM_GetITStatus(TIM2,TIM_IT_Update)==SET)// Check the interrupt flag bit 
	{
		
		Num++;
		TIM_ClearITPendingBit(TIM2,TIM_IT_Update);// Clear interrupt flag bit 
	}
	
}

  3、 ... and .TIM Introduction to library functions

 

TIM_TimeBaseInit(); Initialize the time base unit

TIM_TimeBaseStructInit(), This function can assign structural variables to default values ;

TIM_Cmd(), This is used to enable the counter . Corresponding operation control ;

TIM_ITConfig(), This is used to enable interrupt the output signal ; Corresponding to interrupt output control ;

TIM_InternalClockConfig(). Select the internal clock

TIM_ITRxExternalClockConfig(), First choice ITRx Clocks for other timers ;

 TIM_TIxExternalClockConfig(), choice TIx Capture channel clock ;

TIM_ETRClockMode1Config(). choice ETR Through the external clock mode 1 Input clock ;

TIM_ETRClockMode2Config(), choice ETR Through the external clock mode 2 Input clock ;

TIM_ETRConfig(), Used separately to configure ETR Pin prescaler , Polarity , These filter parameters ;

TIM_PrescalerConfig(), Used to write the pre frequency division value separately

TIM_CounterModeConfig(), Used to change the counting mode of the counter ;

TIM_ARRPreloadConfig(), Automatic reinstaller pre installed function configuration

TIM_SetCounter(), Write a value to the counter ;

TIM_SetAutoreload(), Write a value for the automatic reloader ;

TIM_GetCounter(); Get the value of the current counter , If you want to see where the current counter is , You can call this function , The return value is the value of the current counter ;

TIM_GetPrescaler(); Get the current prescaler value ; If you want to see the prescaled value , Just call this function ;

FlagStatus TIM_GetFlagStatus(TIM_TypeDef* TIMx, uint16_t TIM_FLAG);

void TIM_ClearFlag(TIM_TypeDef* TIMx, uint16_t TIM_FLAG);

ITStatus TIM_GetITStatus(TIM_TypeDef* TIMx, uint16_t TIM_IT);

void TIM_ClearITPendingBit(TIM_TypeDef* TIMx, uint16_t TIM_IT);

These four functions are used to obtain flag bits and clear flag bits

Four , Using variables across files

If you want to use variables across files , There are two ways ：

（ In the main In a statement , Take interrupt function as an example ）

The first one is ： You can use variables on the file , use extern Declare the variables to be used ;

Extern Declare variables , Just tell the compiler , I have now Num This variable , He defined in other documents , As for where , You go by yourself Look for it.

Then the compiler will diligently look for , When the compiler finds it , Will be able to extern The declared variable is used as a reference to the declared file variable .

The second kind ： Copy the interrupt function directly , Put it in main Back ;

5、 ... and . A problem about timer interrupt experiment

Reset it ,Num It's from 1 Start counting , This indicates that the interrupt function enters once immediately after initialization

, The problem is TimeBaseInit function

 

Prescaler has a buffer register , We write values only when updating events , Will really work , So here, in order to make the value work immediately , At the end , An update event is generated manually , such , The value of prescaler is valid , But at the same time , His side effect is , Update events and update interrupts occur at the same time , The update interrupt will set the update interrupt flag , Once we finish initializing , The update interrupt will immediately enter , This is just when the power is on , Immediately enter the reason for the interruption

Solution ： stay TimeBaseInit Behind , Open the front of the interrupt , Call it manually TIM_ClearFlag., Manually clear the update interrupt flag , Can solve .

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