National CP3BT26 User Manual

191

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CP3

BT26

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

/*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
; 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       */
  while (!(acb->ACBst & ACBSDAST) &&
   !(acb->ACBst & ACBNEGACK)&&
   --Timeout) {

if (acb->ACBst & ACBBER) { /* If a bus error occurs while sending address, clear */
acb->ACBst |= ACBBER; /* the error flag and return error status */

   return (ACBERR_COLLISION);
   }
  }

KBD_OUT |= BIT0; // OScope marker

  if (!Timeout)             /* If timeout, signal error            */
   return (ACBERR_TIMEOUT);
                  /* Or if Slave does not reply, report busy/error   */
  else if (acb->ACBst & ACBNEGACK)
   return (ACBERR_NEGACK);
                  /* Otherwise return success            */
  else {

return (ACB_NOERR);
}