STM32 - interrupt overview (interrupt priority)

Interruption refers to the process of computer operation , When there are some unexpected situations that require host intervention , The machine can automatically stop the running program and transfer to the program dealing with new situations , After processing, the program that was suspended will continue to run

STM32 Interrupts and exceptions for

（1） Functions for exceptions and external interrupts , about STM32 In terms of single chip microcomputer , It is made by Cortex-M The kernel provides support , This part of the function sometimes ST The company in Cortex-M Extended or modified from the kernel

（2） The concepts of exception and interrupt are similar , Exceptions can be said to be caused by kernel activities （ For example, there is an error in executing instructions ）, Interruption generally refers to , There are external devices connected to the core （ peripherals ） produce （ For example, peripheral interrupts , Prompt that the data transmission is complete ）, Their triggering or processing mechanism is the same , The two are not strictly distinguished in use

STM32 List of exceptions and interrupts

  You can see , Exceptions are represented by numbers , And there are many interrupt types , Interrupt has priority

Interrupt priority

（1） Interrupt priority is divided into two types , Programmable and non programmable , Programmable representation can modify interrupt priority by itself , What is not programmable cannot be modified

（2） about STM32 Interrupt priority , Determines whose interrupt request the kernel responds to first

（3） The principle of small value first , The smaller the interrupt priority value , Interrupts will be prioritized accordingly

（4） Interrupt priority is configured according to priority grouping

Interrupt priority grouping

With F103 For example ,STM32 Use only on M3 The kernel supports 8bit High priority 4 position bit, That is to say STM32 Support 2^4 Priority

bit7	bit6	bit5	bit4	bit3	bit2	bit1	bit0
Used to express priority				not used , Read back as 0

stay F103 On , Use this 4 individual bit, Organized into 5 Group priority grouping , Each group is divided into 1 Preemptive groups ,1 Sub priority group

Priority groups	preemption	Sub priority	describe
NVIC_PriorityGroup_0	0	0-15	Lord -0bit, Son -4bit
NVIC_PriorityGroup_1	0-1	0-7	Lord -1bit, Son -3bit
NVIC_PriorityGroup_2	0-3	0-3	Lord -2bit, Son -2bit
NVIC_PriorityGroup_3	0-7	0-1	Lord -3bit, Son -1bit
NVIC_PriorityGroup_4	0-15	0	Lord -4bit, Son -0bit

For groups 0, Preemption priority is 0, It means that he didn't preempt the priority ,4 individual bit All are used to represent sub priorities . For groups 1, Preemption priority is 0-1, use 1 individual bit Indicates preemption priority , rest 3 individual bit Indicates sub priority ...

（1） Group by priority , You can manage the response sequence of interrupts

（2） Only preemption priority can be interrupted by preemption , Interrupt nesting occurs , Break occurs when you break , Unable to interrupt , Then it will be suspended

If the event A Preemption priority is 0,B The preemption priority of is 10, stay B In the process of execution ,A Make an interrupt request , Will rob B The right to use the interruption , etc. A After the execution, continue the execution B（ps: If A Don't interrupt the event B,A Will be suspended ）

（3） If the interrupt preemption priority is the same , No preemption

（4） If multiple suspended interrupts have the same preemption priority , Then the child with high priority will go first , If the sub priorities are the same , be IRQ（ Usually refers to external interrupt request ） Small numbers go first （IRQ Source e.g ：stm32f103xe.h）

preemption > Sub priority >IRQ Number

 （5） Programmable priority , Interrupt the controller through nested vectors (NVIC) Realization

NVIC Library function	describe
void NVIC_EnableIRQ(IRQn_Type IRQn)	To interrupt
void NVIC_DisableIRQ(IRQn_Type IRQn)	Disability interruption
void NVIC_SetPendingIRQ(IRQn_Type IRQn)	Set the interrupt suspend position （ Initiate interrupt request , Hardware trigger ）
void NVIC_ClearPendingIRQ(IRQn_Type IRQn)	Clear the interrupt suspend position
uint_32t NVIC_GetPendingIRQ(IRQn_Type IRQn)	Get the interrupt suspension number
void NVIC_SetPriorityIRQ(IRQn_Type IRQn,uint32_t priorty)	Set interrupt priority
uint_32t NVIC_GetPriorityIRQ(IRQn_Type IRQn)	Get interrupt priority
void NVIC_SystemReset(void)	System reset