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I2C don't work using 2 pics

 
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shen
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I2C don't work using 2 pics
PostPosted: Tue Feb 13, 2007 10:13 pm     Reply with quote
Hello all,

I use a 16F877 as a master and a 16F873A as a slave.but they don't work.

here is the code

master

Code:

#include "16F877.h"


#use delay(clock=4000000)                       // for 4Mhz crystal
#fuses XT, NOWDT, NOPROTECT, PUT,NOLVP              // for debug mode
#use I2C(master,sda=PIN_C4,scl=PIN_C3,FORCE_HW)

// These pins are for the Microchip PicDem2-Plus board,
// which is what I used to test the driver.  Change these
// pins to fit your own board.

#define LCD_DB4   PIN_B4
#define LCD_DB5   PIN_B5
#define LCD_DB6   PIN_A5
#define LCD_DB7   PIN_B3

#define LCD_E     PIN_A1
#define LCD_RS    PIN_A3
#define LCD_RW    PIN_A2

// If you only want a 6-pin interface to your LCD, then
// connect the R/W pin on the LCD to ground, and comment
// out the following line.

#define USE_LCD_RW   1     

//========================================

#define lcd_type 2        // 0=5x7, 1=5x10, 2=2 lines
#define lcd_line_two 0x40 // LCD RAM address for the 2nd line

//char mode;
int8  DataA1;//DataA2,DataA3;


int8 const LCD_INIT_STRING[4] =
{
 0x20 | (lcd_type << 2), // Func set: 4-bit, 2 lines, 5x8 dots
 0xc,                    // Display on
 1,                      // Clear display
 6                       // Increment cursor
 };
                             

//-------------------------------------
void lcd_send_nibble(int8 nibble)
{
// Note:  !! converts an integer expression
// to a boolean (1 or 0).
 output_bit(LCD_DB4, !!(nibble & 1));
 output_bit(LCD_DB5, !!(nibble & 2)); 
 output_bit(LCD_DB6, !!(nibble & 4));   
 output_bit(LCD_DB7, !!(nibble & 8));   

 delay_cycles(1);
 output_high(LCD_E);
 delay_us(2);
 output_low(LCD_E);
}

//-----------------------------------
// This sub-routine is only called by lcd_read_byte().
// It's not a stand-alone routine.  For example, the
// R/W signal is set high by lcd_read_byte() before
// this routine is called.     

#ifdef USE_LCD_RW
int8 lcd_read_nibble(void)
{
int8 retval;
// Create bit variables so that we can easily set
// individual bits in the retval variable.
#bit retval_0 = retval.0
#bit retval_1 = retval.1
#bit retval_2 = retval.2
#bit retval_3 = retval.3

retval = 0;
   
output_high(LCD_E);
delay_cycles(1);

retval_0 = input(LCD_DB4);
retval_1 = input(LCD_DB5);
retval_2 = input(LCD_DB6);
retval_3 = input(LCD_DB7);
 
output_low(LCD_E);
   
return retval;   
}   
#endif

//---------------------------------------
// Read a byte from the LCD and return it.

#ifdef USE_LCD_RW
int8 lcd_read_byte(void)
{
int8 low;
int8 high;

output_high(LCD_RW);
delay_cycles(1);

high = lcd_read_nibble();

low = lcd_read_nibble();

return( (high<<4>> 4);
lcd_send_nibble(n & 0xf);
}

//----------------------------
void lcd_init(void)
{
int8 i;

output_low(LCD_RS);

#ifdef USE_LCD_RW
output_low(LCD_RW);
#endif

output_low(LCD_E);

delay_ms(15);

for(i=0 ;i < 3; i++)
   {
    lcd_send_nibble(0x03);
    delay_ms(5);
   }

lcd_send_nibble(0x02);

for(i=0; i < sizeof(LCD_INIT_STRING); i++)
   {
    lcd_send_byte(0, LCD_INIT_STRING[i]);
   
    // If the R/W signal is not used, then
    // the busy bit can't be polled.  One of
    // the init commands takes longer than
    // the hard-coded delay of 60 us, so in
    // that case, lets just do a 5 ms delay
    // after all four of them.
    #ifndef USE_LCD_RW
    delay_ms(5);
    #endif
   }

}

//----------------------------

void lcd_gotoxy(int8 x, int8 y)
{
int8 address;

if(y != 1)
   address = lcd_line_two;
else
   address=0;

address += x-1;
lcd_send_byte(0, 0x80 | address);
}

//-----------------------------
void lcd_putc(char c)
{
 switch(c)
   {
    case '\f':
      lcd_send_byte(0,1);
      delay_ms(2);
      break;
   
    case '\n':
       lcd_gotoxy(1,2);
       break;
   
    case '\b':
       lcd_send_byte(0,0x10);
       break;
   
    default:
       lcd_send_byte(1,c);
       break;
   }
}

//------------------------------
#ifdef USE_LCD_RW
char lcd_getc(int8 x, int8 y)
{
char value;

lcd_gotoxy(x,y);

// Wait until busy flag is low.
while(bit_test(lcd_read_byte(),7)); 

output_high(LCD_RS);
value = lcd_read_byte();
output_low(lcd_RS);

return(value);
}
#endif

void main()
{
     
// The lcd_init() function should always be called once,
// near the start of your program.
SET_TRIS_B( 0x0F );
SET_TRIS_A( 0x00 );

lcd_init();

// Clear the LCD.
printf(lcd_putc, "\f");
delay_ms(500);


   // Test the clear screen and newline commands.
   // Also test that we can write to all 2 lines.
   //printf(lcd_putc, "\fThis is the 1st");
   //printf(lcd_putc, "\nNext is the 2nd");
   ///delay_ms(3000);

   // Test some additional characters.
   //printf(lcd_putc, "\fABCDEFGHIJKLMNOP");
   //printf(lcd_putc, "\nabcdefghijklmnop");
   //delay_ms(3000);

   // Clear the LCD.
   //printf(lcd_putc, "\f");
   //delay_ms(500);
    //delay_ms(250);
   //printf(lcd_putc,"Master start \n\r");
   while(1)
   {

      //Slave A
      i2c_start();
      i2c_write(0xa0 + 1); // read
      //DataA1=i2c_read(1);
      //DataA2=i2c_read(1);
      DataA1=i2c_read(1);
      i2c_stop();
      delay_ms(100);       

      printf(lcd_putc,"\f  %d  ",DataA1);//,DataA2,DataA3);
      delay_ms(100);
   }             

}


slave

[/code]#include <16F873A.h>
#fuses HS,NOWDT,NOPROTECT,NOLVP
#use delay(clock=10000000)
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7)

#use i2c(SLAVE, SDA=PIN_C4, SCL=PIN_C3, address=0xa0)

BYTE address, buffer=0;

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

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
buffer = incoming;
}
if(state == 0x80) //Master is requesting data
{
i2c_write(buffer++);
}
}

void main ()
{
enable_interrupts(GLOBAL);
enable_interrupts(INT_SSP);

while (TRUE) {}
}
Code:
Code:
PCM programmer



Joined: 06 Sep 2003
Posts: 21708

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PostPosted: Tue Feb 13, 2007 11:05 pm     Reply with quote
You've created a modified version of the CCS example code for an
i2c slave. You're using a single byte as the buffer, instead of an array.
That should still work. I think the problem is in your Master code.

See the following post for sample Master code that shows how to talk to
to CCS Ex_Slave.c code:
http://www.ccsinfo.com/forum/viewtopic.php?t=28097&start=9
shen
Guest
PostPosted: Wed Feb 14, 2007 2:25 am     Reply with quote
[/quote]
i2c_start(); //i2c start
i2c_write(0xA0); //address
i2c_write(0x00); // ?????
i2c_start();
i2c_write(0xA1); //ready to read
data = i2c_read(0);
i2c_stop();
printf("read %c \n\r", data);


i2c_write(0x00); // ?????

what does it mean?
PCM programmer



Joined: 06 Sep 2003
Posts: 21708

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PostPosted: Wed Feb 14, 2007 12:39 pm     Reply with quote
The Ex_Slave.c example emulates a 24C00 eeprom.
See this post. Download the 24C00 data sheet from the link in this post.
Study the protocol of the eeprom i2c commands:
http://www.ccsinfo.com/forum/viewtopic.php?t=28531&start=10
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