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[资料分享] msp430F5438A 的中断初步

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发表于 2020-2-13 21:58 | 显示全部楼层 |阅读模式

对于单片机系统,中断是非常重要的一个特性,也是很值得去研究的。

中断的定义:出现需要时,CPU暂时停止当前程序的执行转而执行处理新情况的程序和执行过程。

MSP430F5438A的很多部分都可以产生中断,比如IO口(只有P1,P2口),ADC,Timer_A 等,但是当多种中断在同时等待时,它们之间内部的优先级决定了哪个中断应该先被处理,哪个中断应该后处理。中断处理优先级和中断向量BASEADDRESS如下所示:

image.png

 

暂时只检测只有一个中断的情况,即不用考虑中断优先级的情况。以ADC12_A为中断源.

image.png

ADC12_A的中断标志位寄存器可以记为ADC12IFGx,ADC12IFG0是ADC12IFGx的最低位,当ADC12MEM0装载了转换结果后,这个位置1,而当ADC12MEM0存取后,这个位被重置,它也可以由软件重置。

在IAR_workbench 里面写入以下代码:

#include "msp430x54x.h"

volatile unsigned int result; // Needs to be global in this example,Otherwise, the compiler removes it

// because it is not used for anything.
void InitADC12_A()
{
ADC12CTL0 = ADC12ON+ADC12MSC+ADC12SHT0_15;// Turn on ADC12, set sampling time

ADC12CTL1 = ADC12SHP+ADC12CONSEQ_0; // Use sampling timer, single

ADC12MCTL0 = ADC12SREF_2 + ADC12INCH_3; // ref+=Veref=2.5V, channel = A3

ADC12IE = ADC12IE0; // Enable ADC12IFG.0

ADC12CTL0 |= ADC12ENC; // Enable conversions
}

#pragma vector=ADC12_VECTOR

__interrupt void ADC12ISR (void)

{
switch(__even_in_range(ADC12IV,34))

{

case 0: break; // Vector 0: No interrupt

case 2: break; // Vector 2: ADC overflow

case 4: break; // Vector 4: ADC timing overflow

case 6: // Vector 6: ADC12IFG0

result = ADC12MEM0; // Move results

__bic_SR_register_on_exit(LPM4_bits); // Exit active CPU, SET BREAKPOINT HERE

case 8: break; // Vector 8: ADC12IFG1

case 10: break; // Vector 10: ADC12IFG2

case 12: break; // Vector 12: ADC12IFG3

case 14: break; // Vector 14: ADC12IFG4

case 16: break; // Vector 16: ADC12IFG5

case 18: break; // Vector 18: ADC12IFG6

case 20: break; // Vector 20: ADC12IFG7

case 22: break; // Vector 22: ADC12IFG8

case 24: break; // Vector 24: ADC12IFG9

case 26: break; // Vector 26: ADC12IFG10

case 28: break; // Vector 28: ADC12IFG11

case 30: break; // Vector 30: ADC12IFG12

case 32: break; // Vector 32: ADC12IFG13

case 34: break; // Vector 34: ADC12IFG14

default: break;

}

}

void main(void)

{
InitADC12_A();

WDTCTL = WDTPW+WDTHOLD; // Stop watchdog timer

ADC12CTL0 |= ADC12SC; // Start convn - software trigger

__bis_SR_register(LPM4_bits + GIE); // Enter LPM4, Enable interrupts

__no_operation(); // For debugger

}

在A3口接入电压为1.407V,然后debug,在debug页面发现:

  image.png

image.png

所以成功转换,而且通过中断将结果写入了result里面。

中断的作用说到底只是用来实现突发事件的检测和运行,例如我们也可以实现,运用ADC12的中断实现P11.0上的红色LED灯实现点亮的操作。

#include "msp430x54x.h"

volatile unsigned int result; // Needs to be global in this example,Otherwise, the compiler removes it

// because it is not used for anything.
void InitADC12_A()
{
ADC12CTL0 = ADC12ON+ADC12MSC+ADC12SHT0_15;// Turn on ADC12, set sampling time

ADC12CTL1 = ADC12SHP+ADC12CONSEQ_0; // Use sampling timer, single

ADC12MCTL0 = ADC12SREF_2 + ADC12INCH_3; // ref+=Veref=2.5V, channel = A3

ADC12IE = ADC12IE0; // Enable ADC12IFG.0

ADC12CTL0 |= ADC12ENC; // Enable conversions
}

#pragma vector=ADC12_VECTOR

__interrupt void ADC12ISR (void)

{
switch(__even_in_range(ADC12IV,34))

{

case 0: break; // Vector 0: No interrupt

case 2: break; // Vector 2: ADC overflow

case 4: break; // Vector 4: ADC timing overflow

case 6: // Vector 6: ADC12IFG0

result = ADC12MEM0; // Move results

P11OUT &= ~BIT0; //light red LED

__bic_SR_register_on_exit(LPM4_bits);

case 8: break; // Vector 8: ADC12IFG1

case 10: break; // Vector 10: ADC12IFG2

case 12: break; // Vector 12: ADC12IFG3

case 14: break; // Vector 14: ADC12IFG4

case 16: break; // Vector 16: ADC12IFG5

case 18: break; // Vector 18: ADC12IFG6

case 20: break; // Vector 20: ADC12IFG7

case 22: break; // Vector 22: ADC12IFG8

case 24: break; // Vector 24: ADC12IFG9

case 26: break; // Vector 26: ADC12IFG10

case 28: break; // Vector 28: ADC12IFG11

case 30: break; // Vector 30: ADC12IFG12

case 32: break; // Vector 32: ADC12IFG13

case 34: break; // Vector 34: ADC12IFG14

default: break;

}

}

void main(void)

{
InitADC12_A();

WDTCTL = WDTPW+WDTHOLD; // Stop watchdog timer

ADC12CTL0 |= ADC12SC; // Start convn - software trigger

P11DIR |= BIT0; //设置P11.0为输出

P11OUT |= BIT0;

__bis_SR_register(LPM4_bits + GIE); // Enter LPM4, Enable interrupts

__no_operation(); // For debugger

}

结果成功实现了A4通道的转换,将结果写到了result里面,并且点亮了红色LED灯。


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