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Timer & loops

 
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z3ngew



Joined: 20 Apr 2013
Posts: 50

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Timer & loops
PostPosted: Tue Apr 23, 2013 10:48 am     Reply with quote
Hello everyone,
I have a problem in my code, i am using the ccp module of the pic16f877a, to generate 300hz pulses for my digital servo, but when i use infinite loop to always monitor the value of the variable, (Proteus just go crazy) overflow

here is the code
Code:

#include <16f877a.h>
#use delay(clock = 4Mhz)

#FUSES NOWDT                    //No Watch Dog Timer
#FUSES HS                       //High speed Osc (> 4mhz)
#FUSES NOPROTECT                //Code not protected from reading
#FUSES NOLVP                    //No low voltage prgming, B3(PIC16) or B5(PIC18) used for I/O

#define LCD_ENABLE_PIN PIN_D0
#define LCD_RS PIN PIN_D1
#define LCD_RW PIN PIN_D2
#define LCD_DATA_PORT D
#define LCD_TYPE 2

#include <lcd4.c>
int32 val;
int i = 0;
void main()
{
   lcd_init();
   delay_ms(50);
   
   setup_adc(adc_clock_internal);
   setup_adc_ports(PIN_A0);
   set_adc_channel(AN0);
   delay_ms(10);
   
   output_low(PIN_C2);
   setup_ccp1(CCP_PWM);
   setup_timer_2(T2_DIV_BY_16, 210, 1);
   
   do
   {
      val = read_adc();
      delay_ms(10);
      lcd_gotoxy(1,0);
      printf(lcd_putc, "%lu", val);
   }while(true);
}



Thanks in advance,
z3ngew
Mike Walne



Joined: 19 Feb 2004
Posts: 1785
Location: Boston Spa UK

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PostPosted: Tue Apr 23, 2013 12:02 pm     Reply with quote
Tell us what happens with REAL hardware.

Nobody here can answer Proteus questions!

Mike
z3ngew



Joined: 20 Apr 2013
Posts: 50

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PostPosted: Tue Apr 23, 2013 2:01 pm     Reply with quote
I'm sry for this rush question, the problem was in the code, but i took care of it, and here is the code [analog pot change the duty cycle of 300hz train generated using ccp module]

Code:

#include <16f877a.h>
#DEVICE adc = 10;
#use delay(clock = 4Mhz)


#FUSES NOWDT                    //No Watch Dog Timer
#FUSES HS                       //High speed Osc (> 4mhz)
#FUSES NOPROTECT                //Code not protected from reading
#FUSES NOLVP                    //No low voltage prgming, B3(PIC16) or B5(PIC18) used for I/O

#define LCD_ENABLE_PIN PIN_D0
#define LCD_RS PIN PIN_D1
#define LCD_RW PIN PIN_D2
#define LCD_DATA_PORT D
#define LCD_TYPE 2

#include <lcd4.c>

int32 val;
int i = 0;
void main()
{
   lcd_init();
   delay_ms(50);
   
   setup_adc(adc_clock_internal);
   setup_adc_ports(ALL_ANALOG);
   delay_ms(10);
   
   output_low(PIN_C2);
   setup_ccp1(CCP_PWM);
   setup_timer_2(T2_DIV_BY_16, 210, 1);
   
   do
   {
      set_adc_channel(0);
      val = read_adc();
      set_pwm1_duty(val/2);
      delay_ms(10);
      lcd_gotoxy(1,0);
      printf(lcd_putc, "%lu", val);
   }
   while(true);
}



Good Luck,
z3ngew
Mike Walne



Joined: 19 Feb 2004
Posts: 1785
Location: Boston Spa UK

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PostPosted: Tue Apr 23, 2013 2:20 pm     Reply with quote
Does this mean problem is solved?

If so, you can amend title.

Mike

Last edited by Mike Walne on Tue Apr 23, 2013 2:23 pm; edited 1 time in total
z3ngew



Joined: 20 Apr 2013
Posts: 50

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PostPosted: Tue Apr 23, 2013 2:21 pm     Reply with quote
Yes, it work just fine in simulation, and in real life Smile
Ttelmah



Joined: 11 Mar 2010
Posts: 19496

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PostPosted: Wed Apr 24, 2013 1:04 am     Reply with quote
There are several things I will comment that are faulty with the code as published though....
Code:

   setup_adc(adc_clock_internal);
   //Read the data sheet. Is this clock recommended at your CPU clock
   //rate?. Accuracy will be spoiled by this.....
   setup_adc_ports(ALL_ANALOG);
   //Unless you are using all the pins as analog, don't select this
   //Only select the pins you are going to use. Every pin that is selected to
   //the analog multiplexer, increases the potential noise sources.
   //Microchip have notes about this. Again degrades accuracy...
   delay_ms(10);
   
   output_low(PIN_C2);
   setup_ccp1(CCP_PWM);
   setup_timer_2(T2_DIV_BY_16, 210, 1);
   
   do
   {
      set_adc_channel(0);
      //Read the data sheet again. Is Tacq being satisfied here?.
      //again accuracy will be killed....
      //It'll work, since you are re-selecting the same channel
      //Why?. select the channel once unless you need to change it
      //but if you were changing channels, it wouldn't work...
      val = read_adc();
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