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Problem with PWM

 
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Guest








PostPosted: Tue Nov 18, 2008 2:58 pm     Reply with quote

Hi ! I'm newcomer . May I have a question ?
My problem is "PWM resolutions".I don't know about it .
Would you please help me ?
Thanks very much!
PCM programmer



Joined: 06 Sep 2003
Posts: 21708

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PostPosted: Tue Nov 18, 2008 3:08 pm     Reply with quote

Here's a Piclist article that shows the maximum PWM resolution in bits
based upon the PIC's oscillator frequency:
http://techref.massmind.org/techref/microchip/pwmrescalc.htm

If your question is about selecting 8 or 10-bit resolution with the
CCS compiler, here are some threads that explain it:
http://www.ccsinfo.com/forum/viewtopic.php?t=26751
http://www.ccsinfo.com/forum/viewtopic.php?t=24055
http://www.ccsinfo.com/forum/viewtopic.php?t=22119
http://www.ccsinfo.com/forum/viewtopic.php?t=9927
dientudong



Joined: 18 Nov 2008
Posts: 2

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PostPosted: Wed Nov 19, 2008 2:49 am     Reply with quote

Code:
#include "E:\BAIBAOCAONHOM7\New Folder\taolao.c.h"
#include<16F877A.h>
unsigned char num[8]={0x00,0x15,0x21,0x31,0x48,0x50,0x64,0x78};
unsigned char j ;
void main()
  {
      set_tris_c(0);
      while(1)
       {
          for(j=0;j<8;j++)
           {
             PORTC=num[j];
              delay_ms(1);
           }
       }
  }

My problem is "error in PORTC". Would you please help me ?


Split thread into new topic.
-- Forum Moderator.
Ttelmah
Guest







PostPosted: Wed Nov 19, 2008 5:24 am     Reply with quote

There is nothing called 'PORTC', unless you have declared it...
If you want to write a value to the port, the CCS function, is output_c(num[j]);

This has _nothing_ to do with PWM, which this thread is about.Why post your question here?...
dientudong



Joined: 18 Nov 2008
Posts: 2

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PostPosted: Wed Nov 19, 2008 8:20 am     Reply with quote

Code:
#include <16F877A.h>                                                            //
#use delay(clock=20000000)                                                      //
#include <lcd.c>                                                                //
float vantoc,soxung;                                                            //
int8 a,b,c,d,a1;                                                                //
int16 sovong,i;                                                                 //
///////////////////////////////////////
////////////khai bao va chuong trinh ngat cho TIMER1/////////////////////
#int_TIMER1                                                            //
void TIMER1_isr(void)                                                  //
 {                                                                     //
   soxung=get_timer0();      //get num pulses thatTimer0 counts             //
   set_timer1(65535);        // Trong 1ms                              //
   if(tmr1if==1)             //if Timer1 overflows , tmr1if =1        //
    {                                                                  //
      intcon=0;              //stop ngat (reset interrupt parameters )    //
      a1=1;                  //cho a1=1                                //
    }                                                                  //
 }                                                                     //
//////////////////////////end TIMER1///////////////////////////
//////////////////////////begin main program////////////////////////////


void main()
{
   trisa=0xFF;                        //set RA4 input,pin get pulses from Encoder
   trisb=0;                           //portC is output
   trisc=0;                           // portC is output
   trisd=0;                           // portD is output
   lcd_init();                        //ham khoi tao LCD
   lcd_gotoxy(1,1);                   //row 1 column 1
   lcd_putc("Beginning....");         // print beginning....
   delay_ms(1000);                    //  1s
   lcd_putc('\f');                    //dotpoint  flashs
   setup_timer_2(T2_DIV_BY_2,254,1);  //tao f(pwm)=9775Hz or T(pwm)=0.1023ms
   setup_ccp1(CCP_PWM);               //thiet lap chan CCP1 o che do PWM
   for(i=0;i<1000;i++)                //tu 0 den 1000 thi toc do tang dan
     {
       set_pwm1_duty(i);              // Toc do tang dan
       delay_ms(1);
       set_timer0(0);                 //lam moi Timer0 de chuan bi dem xung
       set_timer1(65535);             //dat gia tri cho Timer1_khoang 1s
       setup_timer_0(RTCC_EXT_H_TO_L|RTCC_DIV_1);
       setup_timer_1(T1_INTERNAL|T1_DIV_BY_1);       
       enable_interrupts(INT_TIMER1);  //cho phep ngat Timer1
       enable_interrupts(GLOBAL);      //cho phep ngat toan cuc
       delay_ms(10);  //

       if(a1==1)   //every Timer1 interrupts, a1=1 ,then calculate vantoc
         {
           vantoc=((float)(60*soxung)/(0.01*100));    //Tinh van toc
           a=vantoc/1000;                             //chia lay phan nguyen
           b=(int)(vantoc-1000*a)/100;                //chia lay phan nguyen
           c=(int)(vantoc-1000*a-100*b)/10;           //chia lay phan nguyen
           d=(int)vantoc%10;                          //chia lay phan du
           ///////////////////toi phan hien thi LCD/////////////////////////////
           lcd_gotoxy(3,3);         //den vi tri hang 3 cot 3
           lcd_putc(a+48);          //in ra a
           lcd_gotoxy(3,4);         //den vi tri hang 3 cot 4
           lcd_putc(b+48);          //in ra b
           lcd_gotoxy(3,5);         //den vi tri hang 3 cot 5
           lcd_putc(c+48);          //in ra c
           lcd_gotoxy(3,6);         //den vi tri hang 3 cot 6
           lcd_putc(d+48);          //in ra d
           lcd_gotoxy(4,3);         //den vi tri hang 4 cot 3
           lcd_putc("vong/phut");   //in ra "vong/phut"
           lcd_gotoxy(2,2);         //den vi tri hang 2 cot 2
           lcd_putc("toc do dc");   //in ra "toc do dc"
           delay_ms(5);             //
           tmr0if=0;tmr1if=0;       //Xoa co tran cua Timer0 va Timer1
         }
     }
}

I have problem in the code. Please help me.
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