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I2C Communication Problem

 
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blacknyellow



Joined: 22 Jul 2013
Posts: 2

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I2C Communication Problem
PostPosted: Mon Jul 22, 2013 8:24 am     Reply with quote
HELLO!!

I want to communicate 2 pics (16f877a) using i2c bus. Its an extremely simple code just to see if its working or not. In this code, I simply want to receive data from the slave and print it on a 2x16 LCD. However on the PROTEUS simulation i only see "FF" transferred. Here is the code for reference.

Code:
 
#include <16F877A.h>
#device adc=8

#FUSES NOWDT                    //No Watch Dog Timer
#FUSES HS                       //High speed Osc (> 4mhz for PCM/PCH) (>10mhz for PCD)
#FUSES NOPUT                    //No Power Up Timer
#FUSES NOPROTECT                //Code not protected from reading
#FUSES NODEBUG                  //No Debug mode for ICD
#FUSES NOBROWNOUT               //No brownout reset
#FUSES NOLVP                    //No low voltage prgming, B3(PIC16) or B5(PIC18) used for I/O
#FUSES NOCPD                    //No EE protection
#FUSES WRT_50%                  //Lower half of Program Memory is Write Protected

#use delay(clock=20000000)
#use i2c(Slave,Fast,sda=PIN_C4,scl=PIN_C3,force_hw,adress=0x90)

int8 n=15,p;
#int_SSP
void  SSP_isr(void)
{  int8 state,incoming;
   
   state=i2c_isr_state();
   
   if((state >= 0x80));
   {
     i2c_write(n);
   } 


}


void main()
{

   setup_adc_ports(AN0);
   setup_adc(ADC_CLOCK_INTERNAL);
   setup_psp(PSP_DISABLED);
   setup_timer_0(RTCC_INTERNAL|RTCC_DIV_1);
   setup_timer_1(T1_INTERNAL|T1_DIV_BY_1);
   setup_timer_2(T2_DIV_BY_1,1,1);
   setup_comparator(NC_NC_NC_NC);
   setup_vref(FALSE);
   enable_interrupts(INT_SSP);
   enable_interrupts(GLOBAL);

   // TODO: USER CODE!!

 while(1)
 {
   
  enable_interrupts(GLOBAL);
   
 }
}



MASTER

Code:


#include <16F877A.h>
#device adc=8

#FUSES NOWDT                    //No Watch Dog Timer
#FUSES HS                       //High speed Osc (> 4mhz for PCM/PCH) (>10mhz for PCD)
#FUSES NOPUT                    //No Power Up Timer
#FUSES NOPROTECT                //Code not protected from reading
#FUSES NODEBUG                  //No Debug mode for ICD
#FUSES NOBROWNOUT               //No brownout reset
#FUSES NOLVP                    //No low voltage prgming, B3(PIC16) or B5(PIC18) used for I/O
#FUSES NOCPD                    //No EE protection
#FUSES WRT_50%                  //Lower half of Program Memory is Write Protected

#use delay(clock=20000000)
#use i2c(Master,Fast,sda=PIN_C4,scl=PIN_C3,force_hw)

#include <flex_lcd_b bacak.c>

int8 data;

void main()
{

   setup_adc_ports(NO_ANALOGS);
   setup_adc(ADC_OFF);
   setup_psp(PSP_DISABLED);
   setup_timer_0(RTCC_INTERNAL|RTCC_DIV_1);
   setup_timer_1(T1_INTERNAL|T1_DIV_BY_1);
   setup_timer_2(T2_DIV_BY_1,1,1);
   setup_comparator(NC_NC_NC_NC);
   setup_vref(FALSE);

   // TODO: USER CODE!!
   lcd_init();
   delay_ms(50);
   printf(lcd_putc,"\f");
   printf(lcd_putc,"yazi=\n");
   while(1)
   {
     i2c_start();
     i2c_write(0x91);
     delay_us(50);
     //i2c_write(0x05);
     //delay_us(50);
     //i2c_stop();
     //i2c_start();
     //i2c_write(0x91);
     data=i2c_read(0);
     i2c_stop();
     printf(lcd_putc,"%d",data);
     
   
   }

}



I would really appreciate if you could help
PCM programmer



Joined: 06 Sep 2003
Posts: 21708

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PostPosted: Mon Jul 22, 2013 10:27 am     Reply with quote
I don't know how to make it work in Proteus. Proteus has weird things
like digital and analog pull-ups. It also may not work without the i2c
debugger turned on. I don't want to solve these problems. I only
use hardware to test i2c. The following method works with two hardware
boards (or two PICs on one board):

Use the CCS example file code, Ex_Slave.c, for the Slave PIC.
It's in this directory:
Quote:

c:\Program Files\picc\Examples\Ex_Slave.c


Use the code in this post for the Master PIC:
http://www.ccsinfo.com/forum/viewtopic.php?t=32368&start=3

Use these connections:
Code:


                +5v
                 |
                 <
                 > 4.7K       
To               <         
Master PIC       |           To Slave PIC
SDA pin   ------------------ SDA pin 
(pin C4)                     (pin C4)   

                +5v
                 |
                 <
                 > 4.7K       
To               <         
Master PIC       |           To Slave PIC
SCL pin   ------------------ SCL pin 
(pin C3)                     (pin C3)   


To
Master PIC                  To slave PIC
ground    ----------------- ground (Vss pins) 
(Vss pins)       |
               -----
                ---  Ground
                 - 
blacknyellow



Joined: 22 Jul 2013
Posts: 2

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PostPosted: Tue Jul 23, 2013 4:04 am     Reply with quote
Thank you sir. Maybe i should test my code on the board
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