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Software PWM 16F628A

 
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A2B



Joined: 22 Mar 2007
Posts: 2

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Software PWM 16F628A
PostPosted: Sat Apr 14, 2007 4:41 am     Reply with quote

Hello,

I'm trying to make a software PWM for the 16F628A. This is for the RGB led i'm trying to make fading. Does anyone have a example for me.

I'm using PCWH compiler version 4.023

Thanks
jecottrell



Joined: 16 Jan 2005
Posts: 559
Location: Tucson, AZ

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PostPosted: Sat Apr 14, 2007 8:25 am     Reply with quote

Use the forum search tool.

This is one of the topics I found helpful when I was faced with a similar project:

http://www.ccsinfo.com/forum/viewtopic.php?t=20050

John
mohikan



Joined: 15 Apr 2007
Posts: 1
Location: oradea, ro

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PostPosted: Sun Apr 15, 2007 3:26 am     Reply with quote

I had a similar project, the LEDs were connected to port RA (RA2=LED Blue, RA3=LED Red, RA4=LED Green) each with its own resistor (RA4 needs pull-up), the software PWM is in timer2 ISR and it's from a Microchip MicroSolutions Newsletter.

Code:

-------------------------------------------------------------------------------------
#include "RGBTest.h"

#INT_TIMER2
void TIMER2_isr()
{
   #asm
      movf    pwm_counter,w
      subwf    pwm_duty_green,w
      rlf    output,f
      movf    pwm_counter,w
      subwf    pwm_duty_red,w
      rlf    output,f
      movf    pwm_counter,w
      subwf    pwm_duty_blue,w
      rlf    output,f
      
      rlf      output,f
      rlf      output,w
      movwf    PORTA
      
      incf    pwm_counter,f
      clrf   output
   #endasm
}

#inline
void set_pwm_duty(ColorType color,int duty)
{
   switch(color)
   {
      case RED:
      {
         pwm_duty_red=duty;
         break;
      }
      case GREEN:
      {
         pwm_duty_green=duty;
         break;
      }
      case BLUE:
      {
         pwm_duty_blue=duty;
         break;
      }
      default:break;
   }
}

void main()
{
   set_tris_a(0x21);//00100001
   setup_timer_0(RTCC_INTERNAL|RTCC_DIV_1);
      setup_timer_1(T1_DISABLED);
      setup_timer_2(T2_DIV_BY_1,0x4E,1);
      setup_comparator(NC_NC_NC_NC);
      setup_vref(FALSE);
      setup_ccp1(CCP_OFF);
      enable_interrupts(INT_TIMER2);
      enable_interrupts(GLOBAL);
      
      printf("\n\rRGBTest v1.0 2006\n\r");
   
   while(TRUE)
   {
      switch(getc())
      {
         case '7':
         {
            ++pwm_duty_red;
            set_pwm_duty(RED,pwm_duty_red);
            break;
         }
         case '4':
         {
            --pwm_duty_red;
            set_pwm_duty(RED,pwm_duty_red);
            break;
         }
         case '8':
         {
            ++pwm_duty_green;
            set_pwm_duty(GREEN,pwm_duty_green);
            break;
         }
         case '5':
         {
            --pwm_duty_green;
            set_pwm_duty(GREEN,pwm_duty_green);
            break;
         }
         case '9':
         {
            ++pwm_duty_blue;
            set_pwm_duty(BLUE,pwm_duty_blue);
            break;
         }
         case '6':
         {
            --pwm_duty_blue;
            set_pwm_duty(BLUE,pwm_duty_blue);
            break;
         }
         default:break;
      }
      printf("> R:%03u G:%03u B:%03u\r",pwm_duty_red,pwm_duty_green,pwm_duty_blue);
   }
}

-------------------------------------------------------------------------------------
#include <16F628A.h>

#FUSES NOWDT                    //No Watch Dog Timer
#FUSES INTRC_IO                 //Internal RC Osc, no CLKOUT
#FUSES PUT                      //Power Up Timer
#FUSES NOPROTECT                //Code not protected from reading
#FUSES BROWNOUT                 //Reset when brownout detected
#FUSES NOMCLR                   //Master Clear pin used for I/O
#FUSES NOLVP                    //No low voltage prgming, B3(PIC16) or B5(PIC18) used for I/O
#FUSES NOCPD                    //No EE protection

#use delay(clock=4000000)
#use rs232(baud=19200,parity=N,xmit=PIN_B2,rcv=PIN_B1,bits=8,stream=UART)
#use fast_io(a)

#define   PORTA   0x05

typedef enum
{
   RED,
   GREEN,
   BLUE
} ColorType;

unsigned int pwm_counter=0;
unsigned int pwm_duty_red=0;
unsigned int pwm_duty_green=0;
unsigned int pwm_duty_blue=0;
unsigned int output=0;
-------------------------------------------------------------------------------------
A2B



Joined: 22 Mar 2007
Posts: 2

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PostPosted: Mon Apr 16, 2007 3:18 am     Reply with quote

Thank you for the code. This is most helpfull
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