Here is sample Code. I not try this code.
You may found other example at CCS Forum. (
http://www.ccsinfo.com/forum/)
SLAVE I2C CODE:#include <16F876A.H>
// 10-bit A/D conversion
#device ADC=10
#fuses HS,NOWDT,NOPROTECT,NOLVP
#use Delay(Clock=20000000)
#use rs232(baud=9600,xmit=PIN_C6,rcv=PIN_C7,brgh1ok)
unsigned char read_i2c(void);
void i2c_interrupt_handler(void);
void i2c_initialize(void);
void i2c_error(void);
void write_i2c(unsigned char transmit_byte);
#INT_SSP
void ssp_interupt ()
{
i2c_interrupt_handler();
}
/* 16f87X bytes */
/* Change it per chip */
#byte PIC_SSPBUF=0x13
#byte PIC_SSPADD=0x93
#byte PIC_SSPSTAT=0x94
#byte PIC_SSPCON1=0x14
#byte PIC_SSPCON2=0x91
/* Bit defines */
#define PIC_SSPSTAT_BIT_SMP 0x80
#define PIC_SSPSTAT_BIT_CKE 0x40
#define PIC_SSPSTAT_BIT_DA 0x20
#define PIC_SSPSTAT_BIT_P 0x10
#define PIC_SSPSTAT_BIT_S 0x08
#define PIC_SSPSTAT_BIT_RW 0x04
#define PIC_SSPSTAT_BIT_UA 0x02
#define PIC_SSPSTAT_BIT_BF 0x01
#define PIC_SSPCON1_BIT_WCOL 0x80
#define PIC_SSPCON1_BIT_SSPOV 0x40
#define PIC_SSPCON1_BIT_SSPEN 0x20
#define PIC_SSPCON1_BIT_CKP 0x10
#define PIC_SSPCON1_BIT_SSPM3 0x08
#define PIC_SSPCON1_BIT_SSPM2 0x04
#define PIC_SSPCON1_BIT_SSPM1 0x02
#define PIC_SSPCON1_BIT_SSPM0 0x01
#define PIC_SSPCON2_BIT_GCEN 0x80
#define PIC_SSPCON2_BIT_ACKSTAT 0x40
#define PIC_SSPCON2_BIT_ACKDT 0x20
#define PIC_SSPCON2_BIT_ACKEN 0x10
#define PIC_SSPCON2_BIT_RCEN 0x08
#define PIC_SSPCON2_BIT_PEN 0x04
#define PIC_SSPCON2_BIT_RSEN 0x02
#define PIC_SSPCON2_BIT_SEN 0x01
#define RX_BUF_LEN 32
#define NODE_ADDR 0x02 /* I2C address of the slave node */
unsigned char slave_buffer[RX_BUF_LEN];
int buffer_index;
int comms_error;
int debug_state;
void i2c_initialize(void)
{
/* Set up SSP module for 7-bit */
PIC_SSPCON1 = 0x36; /* 0011 0101 */
PIC_SSPADD = NODE_ADDR; /* Set the slave's address */
PIC_SSPSTAT = 0x00; /* Clear the SSPSTAT register. */
enable_interrupts(INT_SSP); /* Enable MSSP interrupts. */
}
void i2c_interrupt_handler(void)
{
unsigned char i2c_mask = 0x2D; /* 0010 1101 */
unsigned char temp_sspstat;
unsigned char this_byte;
unsigned char tx_byte;
int x;
/* Mask out the unnecessary bits */
temp_sspstat = PIC_SSPSTAT & i2c_mask;
switch (temp_sspstat)
{
/* Write operation, last byte was an address, buffer is full */
case 0x09: /* 0000 1001 */
/* Clear the receive buffer */
for (x=0; x<RX_BUF_LEN; x++)
{
slave_buffer[x] = 0x00;
}
buffer_index = 0; /* Clear the buffer index */
this_byte = read_i2c(); /* Do a dummy read of PIC_SSPBUF */
debug_state = 1;
break;
/* Write operation, last byte was data, buffer is full */
case 0x29: /* 0010 1001 */
/* Point to the buffer */
this_byte = read_i2c(); /* Get the byte from the SSP */
slave_buffer[buffer_index] = this_byte; /* Put it into the buffer */
buffer_index++; /* Increment the buffer pointer */
/* Get the current buffer index */
/* Subtract the buffer length */
/* Has the index exceeded the buffer length? */
if (buffer_index >= RX_BUF_LEN)
{
buffer_index = 0; /* Yes, clear the buffer index. */
}
debug_state = 2;
break;
/* Read operation; last byte was an address, buffer is empty */
case 0x0C: /* 0000 1100 */
buffer_index = 0; /* Clear the buffer index */
/* Point to the buffer */
tx_byte = slave_buffer[buffer_index]; /* Get byte from the buffer */
write_i2c(tx_byte); /* Write the byte to PIC_SSPBUF */
buffer_index++; /* increment the buffer index */
debug_state = 3;
break;
/* Read operation; last byte was data, buffer is empty */
case 0x2C: /* 0010 1100 */
/* Get the current buffer index */
/* Subtract the buffer length */
/* Has the index exceeded the buffer length? */
if (buffer_index >= RX_BUF_LEN)
{
buffer_index = 0; /* Yes, clear the buffer index */
}
/* Point to the buffer */
/* Get the byte */
tx_byte = slave_buffer[buffer_index];
write_i2c(tx_byte); /* Write to PIC_SSPBUF */
buffer_index++; /* increment the buffer index */
debug_state = 4;
break;
/* A NACK was received when transmitting data back from the master. */
/* Slave logic is reset in this case. R_W=0, D_A=1, and BF=0. */
/* If we don't stop in this state, then something is wrong!! */
case 0x28: /* 0010 1000 */
debug_state = 5;
break;
/* Something went wrong!! */
default:
i2c_error();
break;
}
}
void i2c_error(void)
{
comms_error = 1;
printf ("I2C ERROR!\r\n");
}
void write_i2c(unsigned char transmit_byte)
{
unsigned char write_collision = 1;
while (PIC_SSPSTAT & PIC_SSPSTAT_BIT_BF) /* Is BF bit set in PIC_SSPSTAT? */
{
/* If yes, then keep waiting */
}
while (write_collision)
{
/* If not, then do the i2c_write. */
PIC_SSPCON1 &= ~PIC_SSPCON1_BIT_WCOL; /* Clear the WCOL flag */
PIC_SSPBUF = transmit_byte;
/* Was there a write collision? */
if (PIC_SSPCON1 & PIC_SSPCON1_BIT_WCOL)
{
/* Yes there was a write collision. */
write_collision = 1;
}
else
{
/* NO, there was no write collision. */
/* The transmission was successful */
write_collision = 0;
}
}
PIC_SSPCON1 |= PIC_SSPCON1_BIT_CKP; /* Release the clock. */
}
/* This function returns the byte in SSPBUF */
unsigned char read_i2c(void)
{
return PIC_SSPBUF;
}
void main(void)
{
debug_state = 0;
i2c_initialize();
enable_interrupts(GLOBAL);
printf("i2c slave 09 Jan 2005\n\r\n\r");
while (1)
{
if (debug_state)
{
// printf ("debug state = %d\r\n", debug_state);
debug_state = 0;
}
}
}
