National CP3BT26 manual 191

acb->ACBctl1	= ACBSTOP;	/*	Send STOP bit	*/
return (ACB_NOERR);		/*	Return success status....	*/

}

/*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

; NAME: ACBStartX		Initiates an ACB bus transaction by sending the Start bit, followed by the Slave address
;		and	R/W flag.		Checks for any ACB errors throughout this sequence and returns status.
;
; PARAMETERS:	UBYTE		Slave	-	I2C address of Slave device
;	UBYTE		R_nW	-	Read/Write flag (0x01 or 0x00)
;	UWORD		Count	-	Desired number of bytes (read/write)
;

;CALLS:

;RETURNED: error/success ;%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/

UWORD	ACBStartX (UBYTE Slave, UBYTE R_nW, UWORD Count)
{
ACB_T		*acb;
UWORD		Timeout;			/* Get address of ACB module	*/
acb =		(ACB_T*)ACB_ADDRESS;
					/* If Bus is Busy and we’re NOT the Master, return err	*/
if (acb->ACBcst & ACBBB && !(acb->ACBst & ACBMASTER))
	return (ACBERR_NOTMASTER);				/* If we’re good to go, send Start condition	*/
acb->ACBctl1				= ACBSTART;
					/* Check if we’re the Bus Master with timeout	*/
Timeout =			100;
while (!(acb->ACBst & ACBSDAST) && Timeout--)					/* Related to bus error problem	*/
{	if (acb->ACBst & ACBBER) {				/* If collision occurs, clear error and return status	*/
		acb->ACBst = ACBBER;
	}	return (ACBERR_COLLISION);
}
if (!Timeout)					/* If timeout, we must NOT be the Master...signal error */
	return (ACBERR_NOTMASTER);				/* Now, send the address and R/W flag...	*/
acb->ACBsda			=	Slave R_nW;	/* Send address and R/W flag	*/
Timeout =			1000;		/* Failsafe for lockup	*/
					/* Wait for address to be sent and ACK’d	*/

CP3BT26

while (!(acb->ACBst & ACBSDAST) && !(acb->ACBst & ACBNEGACK)&& --Timeout) {

if (acb->ACBst & ACBBER) { acb->ACBst = ACBBER;

return (ACBERR_COLLISION);

}

}

KBD_OUT = BIT0; // OScope marker

if (!Timeout)

return (ACBERR_TIMEOUT);

/*	If a bus error	occurs while sending address, clear	*/
/*	the error flag	and return error status	*/

/*	If	timeout,	signal error	*/
/*	Or	if Slave	does not reply, report busy/error	*/

else if (acb->ACBst & ACBNEGACK) return (ACBERR_NEGACK);

/* Otherwise return success */

else {

return (ACB_NOERR);

}

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