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dsPIC33fj256MC710 Master- Slave with I2C

 
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bionicbot



Joined: 05 Aug 2010
Posts: 5
Location: UK

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dsPIC33fj256MC710 Master- Slave with I2C
PostPosted: Wed Sep 29, 2010 10:54 am     Reply with quote
Dear All,
I have some problem with using two of dspic33fj256mc710 for communication as master and slave. I need to send data from master to on-off led in slave, but it doesn't work. I've tried to read from many posts and apply to my work but it's still the same problem. This is my master code.
Code:

#include <33FJ256MC710.h>
#fuses XT,PR_PLL,NOWDT,NOCOE,NODEBUG, NOWRTB, NOPUT, NOWRTSS, NOWRT, NOPROTECT, NORSS
#use delay(crystal=10000000,clock=20000000)
//#use rs232(baud=9600,uart1)
#use i2c(master, I2C1,force_hw)

#define slave01 0x52

BYTE read_slave(BYTE address)
{
   BYTE data;
   i2c_start();
   i2c_write(address);
   i2c_write(0x00);
   i2c_start();
   i2c_write(address+1);
   data = i2c_read(0);
   i2c_stop();
   return(data);
}

void write_slave(BYTE address,BYTE data)
{
   i2c_start();
   i2c_write(address);
   i2c_write(0x00);
   i2c_write(data);
   i2c_stop();
}

void main(void)
{
  int8 count;
  set_tris_g(0x0F);
  setup_adc_ports(no_analogs);

  while(TRUE)
 {
   for(count=0;count<4;count++)
   {
      write_slave(slave01,count);
      
         // on-off led in master to check the data is corrected
          if(bit_test(count,0))
           {
            output_high(PIN_G6);
           }
         else
            output_low(PIN_G6);

         if(bit_test(count,1))
            output_high(PIN_G7);
         else
            output_low(PIN_G7);

      delay_ms(1000);
   }
   
 }
}

And my slave code is:
Code:

#include <33FJ256MC710.h>
#fuses XT,PR_PLL,NOWDT,NOCOE,NODEBUG, NOWRTB, NOPUT, NOWRTSS, NOWRT, NOPROTECT, NORSS
#use delay(crystal=10000000,clock=20000000)
//#use rs232(baud=9600,uart1)
#use i2c(SLAVE, I2C1, address=0x52)

BYTE address,buffer[0x10],data1;

#INT_SI2C
void ssp_interupt()
{
   BYTE incoming, state;
   state = i2c_isr_state();
   output_high(PIN_G6);
   output_high(PIN_G7);
   if(state < 0x80)
   {
      incoming = i2c_read();
      if(state == 1)
         address = incoming;
      if(state == 2)
      {
         data1 = incoming;
         // on-off led by the data has been sent
         if(bit_test(data1,0))
              output_high(PIN_G6);
         else
              output_low(PIN_G6);
         if(bit_test(data1,1))
              output_high(PIN_G7);
         else
              output_low(PIN_G7);
      }
   }
   if(state == 0x80)
   {
      i2c_write(buffer[address]);
   }
}

void main(void)
{
  int8 count;

  //set_tris_g(0x0F);
  setup_adc_ports(no_analogs);
  enable_interrupts(INTR_GLOBAL);
  enable_interrupts(INT_SI2C);
  enable_interrupts(INT_MI2C);
 
  while(TRUE)
 {
      
 }
}

I also used the oscilloscope to check the signal on SDA and SCL from master, it's correct on both of them. But when I put the command to on-off LED in interupt function of slave, it doesn't work. I tried to set address for slave at 0xA0 and 0x52 as I read from many post but it's still the same problem. I'm afraid that the interupt it doesn't work. Anybody have idea about this problem, please let me know.
Thanks in advance.
Ttelmah



Joined: 11 Mar 2010
Posts: 19497

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PostPosted: Wed Sep 29, 2010 3:21 pm     Reply with quote
The lines operating the LEDs, will stay high most of the time in the slave. You are setting them high at the start of the interrupt handler. Remember the handler will be called for the 'stop' transaction, as well as for the data transactions, so the lines may be driven low for a short moment but will then go high again...
That the interrupt is called for 'stop', is not obvious in a lot of the paperwork. Most of the timing diagrams terminate at this point, and just a few of the data sheets add the comment that this happens...

Set the lines high at the start of the main, and remove the lines setting them high at the start of the interrupt.

Best Wishes
bionicbot



Joined: 05 Aug 2010
Posts: 5
Location: UK

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PostPosted: Wed Sep 29, 2010 5:05 pm     Reply with quote
Ttelmah, Thank you very much for reply. Sorry for post a bit mistake of the code about the two lines in the interupt function. The two lines which on LED, I just put it to check the inturupt fnc work or not and I forgot to remove befor I put on the web. When I run this code LED doesn't on as we require, that mean why I thought that the interupt function doesn't work. I'm not sure about setting the interupt function it's correct? Do you have any idea? Thank again.
bionicbot



Joined: 05 Aug 2010
Posts: 5
Location: UK

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PostPosted: Wed Sep 29, 2010 5:17 pm     Reply with quote
Ttelmah, I have changed the code as you have commented but LEDs are still not working. This is my code.
Code:

#INT_SI2C
void ssp_interupt()
{
   BYTE incoming, state;

   state = i2c_isr_state();
   
   if(state < 0x80)
   {
      incoming = i2c_read();
      if(state == 1)
         address = incoming;
      if(state == 2)
      {
         data1 = incoming;
      }
   }
   if(state == 0x80)
   {
      i2c_write(buffer[address]);
   }
}

void main(void)
{
  int8 count;

  //set_tris_g(0x0F);
  setup_adc_ports(no_analogs);
  enable_interrupts(INTR_GLOBAL);
  enable_interrupts(INT_SI2C);
  enable_interrupts(INT_MI2C);
 
  while(TRUE)
 {
     // on-off led by the data has been sent
   if(bit_test(data1,0))
      output_high(PIN_G6);
   else
      output_low(PIN_G6);
   if(bit_test(data1,1))
      output_high(PIN_G7);
   else
      output_low(PIN_G7);      
 }
}

I'm not sure about setting the interrupt, it's correct? Because when I turned on LED in the interuppt function, LEDs don't work.
Thanks again.
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