系统时钟和定时器——PWM定时器

#include "2440addr.h"

#define U32 unsigned int

typedef unsigned char BOOL;

#define TRUE       1  

#define FALSE     0

BOOL stop;

static void __irq Key3_ISR(void)         /*暂停键，关闭蜂鸣器*/

{

       rSRCPND = rSRCPND | (0x1<<2); /*定义EINT2*/

       rINTPND = rINTPND | (0x1<<2);

       rTCON &= ~0x8;          /*禁止定时器自动重载，即关闭定时器0111*/

       stop = TRUE;

}

void __irq Key2_ISR(void)          /*重启键，开启蜂鸣器*/

{

       rSRCPND = rSRCPND | 0x1; /*定义EINT0*/

       rINTPND = rINTPND | 0x1;

       stop = FALSE;

}

void delay(int a)

{

       int k;

       for(k=0;k

              ;

}

void Main(void)

{

       int freq;

       rGPBCON = 0x155556;        /*B0为TOUT0，B5~B8为输出，给LED      0001 0101 0101 0101 0101 0110*/

       rGPBUP  = 0x7ff;          /*0111 1111 1111关闭上拉使能*/

       rGPFCON = 0xaaaa;             /*F口为EINT，给按钮               1010 1010 1010 1010*/

       /*按钮的一些必要配置*/

       rSRCPND = 0x0f;               /*中断设置*/

       rINTMSK = ~0x0f;

       rINTPND =0x0f;

       rEXTINT0 = 0x2222;             /*EINT0/EINT1均设置为下降沿触发*/

       freq = 2500;

       rTCFG0 &= 0xFFFF00;

       rTCFG0 |= 0x31;    /*prescal 是49 3*16+1=49 timer0 and timer1*/

       rTCFG1 &= ~0xF;    /*低四位清零 divider value=1/2，因为PCLK为50MHz，所以50MHz/50/2=500kHz/

       rTCNTB0 = 5000;    /*定时器计数初始值*/

       rTCMPB0 = freq;    /*定时器比较值*/

       rTCON &= ~0x1F;       

       rTCON |= 0xf;              /*死区无效，自动装载，电平反转，手动更新，定时器开启*/

       rTCON &= ~0x2 ;  /*手动更新位清零，PWM开始工作*/

       pISR_EINT0 = (U32)Key2_ISR;

       pISR_EINT2 = (U32)Key3_ISR;

       stop = FALSE;

       rGPBDAT = ~0x60;              /*两个LED亮*/

       while(1)

       {

              /*频率递增*/

              for ( ; freq<4950 ; )

              {

                     freq+=10;

                     rTCMPB0 = freq;          /*重新赋值*/

                     delay(20000);

                     while (stop == TRUE)          /*是否暂停*/

                     {

                            delay(1000);

                            if (stop ==FALSE)        /*判断是否重启*/

                            {

                                   rTCON &= ~0x1F;

                                   rTCON |= 0xf;

                                   rTCON &= ~0x2 ;               /*恢复PWM功能*/

                            }

                     }

                     /*4个LED随着频率的高低，时灭时亮。灯亮的数目4-3-2-1*/

                     if(freq == 100)

                            rGPBDAT = ~0x560; /*0001 1110 0000 取反之后1110 0001 1111*/

                     if(freq == 1300)

                     rGPBDAT = ~0x160;         /*1110 0000   取反之后   0001 1111*/

                     if(freq == 2500)

                            rGPBDAT = ~0x60; /*0110 0000    取反之后    1001 1111*/

                     if(freq == 3700)

                            rGPBDAT = ~0x20; /*0010 0000   取反之后     1101 1111*/

                     if(freq == 4900)

                            rGPBDAT = ~0x0; /*0000         取反之后     1111111111*/

              }

              /*频率递减*/

              for( ; freq>50 ; )

              {

                     freq-=10;

                     rTCMPB0 = freq;

                     delay(20000);

                     while (stop == TRUE)

                     {

                            delay(1000);

                            if (stop ==FALSE)

                            {

                                   rTCON &= ~0x1F;

                                   rTCON |= 0xf;

                                   rTCON &= ~0x2 ;

                            }

                     }

                     if(freq == 100)

                            rGPBDAT = ~0x560;

                     if(freq == 1300)

                            rGPBDAT = ~0x160;

                     if(freq == 2500)

                            rGPBDAT = ~0x60;

                     if(freq == 3700)

                            rGPBDAT = ~0x20;

                     if(freq == 4900)

                            rGPBDAT = ~0x0;

              }

       }    

}

TOUT输出的波形是：