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ST7 S/W IMPLEMENTATION OF I2C BUS MASTER

/* MODEL => [static] type_name var_name; or #define

*/

void delay (unsigned char time)

{

#ifdef __HIWARE__

asm

{

nop

/* Time is stored on the Accumulator automatically */

again: DEC

A

/* When the function is called.

*/

JRNE

again

/* (15+6*time) clock cycles

*/

}

#else

#ifdef __CSMC__

{

_asm ("nop");

_asm("again: DEC A");

_asm(" JRNE again");

}

#endif

#endif

}

/*--------------------------------------------------------------------------

ROUTINE NAME : I2Cm_Start

INPUT/OUTPUT : None.

DESCRIPTION : Generates I2C-Bus Start Condition.

COMMENTS

:

--------------------------------------------------------------------------*/

void I2Cm_Start (void)

{

ClrBit(PADDR,SDA);

/* Configure SDA and SCL as floating input to have a high state */

ClrBit(PADDR,SCL);

delay(10);

SetBit(PADDR,SDA);

/* Configure SDA as output open drain to have a low state */

delay(4);

/* Waits 39 cycles=4.875µs at a Fcpu=8MHz to keep the high state on SCL */

SetBit(PADDR,SCL);

/* Configure SCL as output open drain to have a low state */

delay(6);

/* Delay to wait after a START

*/

}

/*--------------------------------------------------------------------------

ROUTINE NAME : I2Cm_Stop