PIC16 PCF8591

Simulate IIC mode PIC16F887 XCV1.41

#define SCL_H TRISC0 = 0, RC0 = 1 /* SCL pin is set high IIC two communication ports */

#define SCL_L TRISC0 = 0, RC0 = 0 /* Set SCL pin low */

#define SDA_H TRISC1 = 0, RC1 = 1 /* Set SDA pin high */

#define SDA_L TRISC1 = 0, RC1 = 0 /* Set SDA pin low */

#define SDA_IN TRISC1 = 1 /* SDA input mode */

#define SDA_OUT TRISC1 = 0 /* SDA output mode */

#define SDA_VAL RC1 /* SDA bit value to read */

#define TRUE 1

#define FALSE 0

#define PCF8591Address 0x90 /*Device address of PCF8591*/

#define PCF8591Control 0x40 /* AD conversion start */

void start( void )

{

SCL_H;

SDA_H;

NOP();

SDA_L;

NOP();

SCL_L;

NOP();

}

void stop( void )

{

SDA_L;

NOP();

SCL_H;

NOP();

SDA_H;

NOP();

}

void mack( void )

{

SDA_L;

NOP(); NOP();

SCL_H;

NOP();

SCL_L;

NOP(); NOP();

SDA_H;

NOP();

}

void mnack( void )

{

SDA_H;

NOP(); NOP();

SCL_H;

NOP();

SCL_L;

NOP(); NOP();

SDA_L;

NOP();

}

char check( void )

{

char slaveack;

SDA_H;

NOP(); NOP();

SCL_H;

NOP(); NOP();

SDA_IN;

NOP(); NOP();

slaveack = SDA_VAL; /* Read SDA value*/

SCL_L;

NOP();

SDA_OUT;

if ( slaveack )

return(FALSE);

else return(TRUE); /* Slave 0 represents a response, please note! ! */

}

/********************************************************************

* Function name: write1

* Function: Send a 1 to the I2C bus

* Parameters: None

* Return value: None

********************************************************************/

void write1( void )

{

SDA_H;

NOP();

SCL_H;

NOP();

SCL_L;

NOP();

}

/********************************************************************

* Function name: write0

* Function: Send a 0 to the I2C bus

* Parameters: None

* Return value: None

********************************************************************/

void write0( void )

{

SDA_L;

NOP();

SCL_H;

NOP();

SCL_L;

NOP();

}

/********************************************************************

* Function name: write1byte

* Function: Send one byte of data to the I2C bus

* Parameter: WriteData -- sent data

* Return value: None

********************************************************************/

void write1byte( unsigned char WriteData )

{

unsigned char i;

for ( i = 8; i > 0; i-- )

{

if ( WriteData & 0x80 )

write1();

else write0();

WriteData <<= 1;

}

SDA_H;

NOP();

}

/********************************************************************

* Function name: writeNbyte

* Function: Send N bytes of data to the I2C bus

* Parameter: outbuffer -- pointer to the first address where the sent data is stored

* n -- the number of data

* Return value: 1 - successful sending, 0 - failed

********************************************************************/

unsigned char writeNbyte( unsigned char * outbuffer, unsigned char n )

{

unsigned char i;

for ( i = 0; i < n; i++ )

{

write1byte( *outbuffer );

if ( check() )

{

outbuffer++;

}else {

stop();

return(FALSE);

}

}

stop();

return(TRUE);

}

/********************************************************************

* Function name: read1byte

* Function: Read a byte from the I2C bus

* Parameters: None

* Return value: the data read

********************************************************************/

unsigned char read1byte( void )

{

unsigned char ReadData = 0x00, i;

unsigned char flag;

for ( i = 0; i < 8; i++ )

{

SDA_H;

NOP();

SCL_H;

SDA_IN;

NOP();

flag = SDA_VAL;

ReadData <<= 1;

if ( flag )

ReadData |= 0x01;

SDA_OUT;

SCL_L;

NOP();

}

return(ReadData);

}

/********************************************************************

* Function name: readNbyte

* Function: Read N bytes of data from the I2C bus

* Parameter: inbuffer -- the first address where the data is stored after reading

* n -- the number of data

* Return value: None

********************************************************************/

void readNbyte( unsigned char * inbuffer, unsigned char n )

{

unsigned char i;

for ( i = 0; i < n; i++ )

{

inbuffer[i] = read1byte();

if ( i < (n - 1) )

mack();

else mnack();

}

stop();

}

/********************************************************************

* Function name: PCF_Write_DAC()

* Function: Write the data to be converted into PCF8591 DAC

* Parameter: DACdata -- data to be written

* Return value: 1 - write successful, 0 - fail

********************************************************************/

unsigned char PCF_Write_DAC( unsigned char DACdata )

{

start();

write1byte( PCF8591Address ); /* device address*/

if ( check() )

write1byte( PCF8591Control ); /* write control word*/

else

return(0);

if ( check() )

write1byte( DACdata ); /* DAC data to be converted*/

else

return(0);

if ( check() )

stop();

else return(0);

delay_ms( 10 ); /* Wait for DAC to complete internal writing*/

return(1);

}

Think of DAC in a simpler way:

First initialize the hardware IIC:

    TRISC = 0b00011000;

SSPCON = 0b00101000;

SMP = 0;

SSPADD = 4;

If you want a DAC, send a voltage:

            SEN = 1;

            iic_send_char( 0x90 ); //iic writes iic device address

iic_send_char( 0x40 ); //Write DAC conversion signal

iic_send_char( zhengxian[ccc] ); // write voltage

            PEN = 1;

in:

void iic_send_char( char R )

{

SSPBUF = R;

while ( R_nW == 1 )

;

}