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i2c interrupt for data byte doesn't pop

 
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gil.fonea@sds-tech.com



Joined: 24 Mar 2010
Posts: 24

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i2c interrupt for data byte doesn't pop
PostPosted: Sun Sep 19, 2010 9:01 am     Reply with quote
Hi,

I am using PIC18f662 and a CCS compiler ver 4.077 as a i2c slave.
The master send me 1 byte of data. The ssp_interupt() works for the address byte, but not coming again for the data byte (I can see the ack for the data byte over the oscilloscope).
This is my code:
Code:

#INT_SSP
void ssp_interupt()
{
BYTE incoming, state;
   
output_high(no_connected_RA5);     //gil debug   
CKP = 0;

state = i2c_isr_state();
   
if(state <= 0x80)                     //Master is sending data
  {
   incoming = i2c_read();
   if(state == 1)                     //First received byte is address
      address = incoming;
   if(state == 2)                     //Second received byte is data
      rcv_buffer[address] = incoming;
  }
if(state == 0x80)                     //Master is requesting data
  {
   i2c_write(rcv_buffer[address]);
  }

CKP = 1;   
output_low (no_connected_RA5);

}

Please help/
_________________
Gil F.
PCM programmer



Joined: 06 Sep 2003
Posts: 21708

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PostPosted: Sun Sep 19, 2010 6:05 pm     Reply with quote
Show us both the master and the slave code.
But show us very short versions of each of these programs. They
must be compilable. Don't include any unneeded "Wizard" code.

For example, here is a short i2c Master test program. Your program
could be made shorter than this:
http://www.ccsinfo.com/forum/viewtopic.php?t=32368&start=3

The i2c Slave code should include the code that you posted above, and
a very small main(), and #include, #fuses, #use delay() and #use i2c(),
and no unnecessary code.
gil.fonea@sds-tech.com



Joined: 24 Mar 2010
Posts: 24

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i2c interrupt for data byte doesn't pop
PostPosted: Mon Sep 20, 2010 1:37 am     Reply with quote
Hi,

Follow are the master and slave codes.
The original issue is that removing the printf (denoted below) causes i2c reception to fail (no end bit is sent by the master and no second interrupt pops on the slave side).

Thanks,

--------------- slave code --------------------------
Code:

#include "16f882.h"
#fuses  INTRC, NOWDT, NOPROTECT, NOPUT

#fuses  BORV21

#use delay(internal=8M)
#use rs232(baud=19200, xmit=PIN_C6, rcv=PIN_C7)
#use i2c(SLAVE, SDA=PIN_C4, SCL=PIN_C3, address=0x52)

#use i2c(SLAVE, SDA=PIN_C4, SCL=PIN_C3, address=0x52)

#define I2C_CMD_WRITE   0x00


#INT_SSP
void ssp_interupt()
{
BYTE incoming, state;
   
output_high(no_connected_RA5);     

CKP = 0;

state = i2c_isr_state();
   
if(state <= 0x80)                     //Master is sending data
  {
   incoming = i2c_read();
   if(state == 1)                     //First received byte is address
      address = incoming;
   if(state == 2)                     //Second received byte is data
      rcv_buffer[address] = incoming;
  }
if(state == 0x80)                     //Master is requesting data
  {
   i2c_write(rcv_buffer[address]);
  }

CKP = 1;   
output_low (no_connected_RA5);

}


---------------- slave main loop -----------------------
Code:

void main(void)
{
   BYTE i;

   setup_oscillator(OSC_8MHZ);
   INTCON = 0x00; // clear all interrupts
   Init_reset();       
   event_in = no_event;
   
   SEN = 1;
   
   //--------------------------------------
   // enable interrupts here
   //--------------------------------------
    enable_interrupts (INT_SSP);
    enable_interrupts (GLOBAL);

    disable_interrupts (GLOBAL);

   //--------------------------------
   // enter sleep mode
   //--------------------------------
     
     
   while(1)
   {
      if (event_in == no_event)  // check for no event
         {
            INTCON = 0xD0;       // enable interrupts

            setup_uart(FALSE);
           
            SLEEP();

            setup_uart(TRUE);
            printf(" exit_sleep " );    <--------- removing this printf causes i2c reception to fail
           
          }
          INTCON = 0x00;        // disable interrupts

      //--------------------------------
      // uart rx flag
      //--------------------------------


      if (uart_rx_flag != 0)  uart_rx_flag = 0;
     
     
      execute_event();

   }
}

--------------- master code --------------------------
Code:

#define set_i2c_master()    #use i2c(MASTER, SDA=PIN_C4, SCL=PIN_C3)   

#define set_i2c_slave()    #use i2c(SLAVE, SDA=PIN_C4, SCL=PIN_C3, address=0x50)


void write_i2c(BYTE command)
{
   
      
   BYTE ack_result[2];


   //---------------------------
   set_i2c_master()
   //---------------------------

   i2c_start();
   
   ack_result[0] = i2c_write(0x52 | I2C_CMD_WRITE);
   ack_result[1] = i2c_write(command);

   
   
   i2c_stop();



   // return to slave mode ...
   //---------------------------
   set_i2c_slave()
   //---------------------------
   
   
}

_________________
Gil F.
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