isr.c

codewarrior dsp 56807 中断编程实现灯闪烁,有详细的注释

/*  metrowerks sample code  */



/*
	this source illustrates code called by ISR 
	and #pragma directives necessary for ISR-safe code
		
*/



#include <stdio.h>
#include "DSP56F807.h"
#include "led.h"
#include "isr.h"

static void delay ();

int led_position = 0;
int led_group = 0;

void initIsr ()
{ /////111111111111111111
	asm (bfset #$0100,sr);
	asm (bfclr #$0200,sr);			/* allow lowest priority */
	asm (bfset #$fe12,X:IPR);		/* enable both IRQ A & B, and all other interrupts */
/// 1111 1110 0001 0010 
	asm (bfset #$0100,X:GPR10);		/* Timer A Ch 0 lowest priority */	
//0000 0001 0000 0000 中断优先级寄存器组 #define GPR10	ITCN_BASE + 0xa 
	/* stop timer 0*/
	asm	(move #$0000,X:TMRA0_CTRL); //定时器A, 通道0控制寄存器
///000（计数器模式控制位）   0 000(计数器源控制位，计数器输入引脚#0) 0 0  
// 000 0000 
	
	/* timer 0 compare 1/2, load, counter */
	asm (move #$ffff,X:TMRA0_CMP1);  //定时器A, 通道0比较寄存器1
	asm (move #$0000,X:TMRA0_CMP2);///比较寄存器2
	
	asm (move #$ffff,X:TMRA0_LOAD);//定时器A, 通道0 预置寄存器
	asm (move #$ffff,X:TMRA0_CNTR);//定时器A, 通道0 计数寄存器
	
	/* enable timer0 compare interrupt */
	asm (move #$4000,X:TMRA0_SCR); //定时器A, 通道0 状态和控制寄存器
// 0100 0000 0000 0000  比较中断允许
	/* timer0 primary source on bus / 128 */
	asm (move #$3e30,X:TMRA0_CTRL);//定时器A, 通道0 控制寄存器
//001(计数器模式控制位：在主时钟的上升沿计数) 
//1*111(主计数源控制位：预分频（IP总线时钟128分频）)  
//0*0(第二计数源控制位：计数器输入引脚#0) 
//0(单次计数控制位ONCE，：连续计数) 1(LENGTH) 1(DIR) *0(Co Init) 000(OutPut Mode)
}



/* Interrupt-safe function: 
A function call that conserves all register content
(excluding PC,SP) across a call. Please note that 
Standard C libary is not interrupt-safe */


/* ISR that call non interrupt-safe functions need
#pragma interrupt saveall to:

1. call a runtime routine that save all register (except SP,PC)
2. return with RTI */
#pragma interrupt saveall
//已经看懂//已经看懂//已经看懂//已经看懂//已经看懂//已经看懂
void isrIRQA ()
{ //////22222222222222222
	/* debounce key with delay for simplicity, disadvantage:
	1. high latency
	2. no repoll of switch state after deounce delay */
	
	/////////////+++++++++++++++++++++++++++++++++
	delay ();  
	/////////////////////++++++++++++++++++++++++++++++++
	
	puts ("IRQA detected");	/* Standard C library call */
	
	///led_group 若初始为0 则值为 1，灯1灭； 否则值为 3 ，灯3 灭
	offLED (led_group == 0 ? 1 : 3);	/* switch off LED from last group */
//offLED() 函数 声明和定义分别在 led.h 和 led.c 中	
	
	
	led_group = 0;  
	///**isrIRQA ()函数 与 void isrIRQB ()函数 的唯一区别******
}


/* ISR that call non interrupt-safe functions need
#pragma interrupt saveall to:

1. call a runtime routine that save all register (except SP,PC)
2. return with RTI */
#pragma interrupt saveall
//已经看懂//已经看懂//已经看懂//已经看懂//已经看懂//已经看懂
void isrIRQB ()
{  ////////33333333333333333333
	/* debounce key with delay for simplicity, disadvantage:
	1. high latency
	2. no repoll of switch state after deounce delay */
	
	/////////////+++++++++++++++++++++++++++++++++
	delay ();  
	/////////////////////++++++++++++++++++++++++++++++++
	

	puts ("IRQB detected");	/* Standard C library call */

	///led_group 若初始为0 则值为 1，灯1灭； 否则值为 3 ，灯3 灭
	offLED (led_group == 0 ? 1 : 3);	/* switch off LED from last group */
//offLED() 函数 声明和定义分别在 led.h 和 led.c 中

	led_group = 1;  
	//////**isrIRQA ()函数 与 void isrIRQB ()函数 的唯一区别******
}


/* ISR that does not call interrupt-unsafe functions can use #pragma interrupt to:
1. save all used register
2. return with RTI
*/
#pragma interrupt
void isrTimerA0Compare ()
{  ////4444444444444444
	/* next LED */
///	led_group == 0 ? 1 : 3；若led_group=0成立，则此表达式的值为 1，从而改变第
//1 个灯的明亮状态
//若不成立，则此表达式的值为 3，从而改变第3 个灯的明亮状