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16F689 I2C

 
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16F689 I2C
PostPosted: Fri Feb 12, 2010 7:26 pm     Reply with quote
I am using 16F689 to build 2 boards to test the I2C operation but found that it is not working.

Master
Code:

#include <16F689.h>
#device *=16
#device adc=8

#FUSES NOWDT
#FUSES MCLR, HS, NOBROWNOUT
#use delay(clock=20000000)
#use i2c(master,sda=PIN_B4,scl=PIN_B6)
#users232(baud=19200,parity=N,xmit=PIN_A0,rcv=PIN_A1,bits=8,errors, stream=PC)

main()
{
   int c;

   delay_ms(2000 );
   fprintf(PC,"Ready..\n\r");

   while (true) {
      i2c_start();
      i2c_write(0xa0);
      //  delay_ms(100);
      i2c_write(50);
      //  delay_ms(100);
      i2C_start();
      i2c_write(0xa1);
      //  delay_ms(100);
      c =  i2c_read(0);
      fprintf(PC, "%c\n\r", c );
   }
}


Slave
Code:

#include <16F689.h>
#device *=16
#device adc=8

#FUSES NOWDT
#FUSES MCLR, HS, NOBROWNOUT
#use delay(clock=20000000)
#use i2c(Slave,sda=PIN_B4,scl=PIN_B6,address=0xa0,force_hw)

int n;

#int_SSP
SSP_isr()
{
   int state;

   state = i2c_isr_state();

   if ( state >= 0x80 )
      i2c_write( n );
   else if (state > 0 ) {
      output_toggle( pin_c4 );
      n = i2c_read();
   }
   else {
       output_toggle( pin_c3 );
   }
}

Problem

1. Master never work with force_hw
2. Slave - no data was read BUT the READ ADDRESS MATCH (pin_c3 toggled).
3. Slave - no data was read because PIN_C4 not toggled.

Work around

1. I put some extra delay_ms() instruction but no help.
2. Slave can write data (Master can read).

Any idea?
Ttelmah
Guest
PostPosted: Sat Feb 13, 2010 2:52 am     Reply with quote
You need to read the address (state==0). The flag saying that a byte has been received, is not cleared unless you do....

Best Wishes
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