i2c_isr.c

Go to the documentation of this file.

/*
 * i2c_isr.c
 *
 *  Created on: 07/01/2011
 *      Author: fanl
 */

#include "../lpc_config.h"
#include "i2c.h"
#include "../uart/uart.h"

extern volatile int I2CMasterState;
extern volatile int I2CCmd;
extern volatile char I2CMasterBuffer[BUFSIZE];
extern volatile int I2CReadLength;
extern volatile int I2CWriteLength;
extern volatile int RdIndex;
extern volatile int WrIndex;


void I2C0MasterHandler( void ) __attribute__ ((interrupt("IRQ")));

/*****************************************************************************
** Function name:               I2C0MasterHandler
**
** Descriptions:                I2C0 interrupt handler, deal with master mode
**                              only.
**
** parameters:                  None
** Returned value:              None
**
*****************************************************************************/
void I2C0MasterHandler(void)
{
  char StatValue;
  uart_putc('i');
  /* this handler deals with master read and master write only */
  StatValue = I22STAT;
  switch ( StatValue )
  {
        case 0x08:                      /* A Start condition is issued. */
        I22DAT = I2CMasterBuffer[0];
        I22CONCLR = (I2CONCLR_SIC | I2CONCLR_STAC);
        I2CMasterState = I2C_STARTED;
        break;

        case 0x10:                      /* A repeated started is issued */
        if ( I2CCmd == LM75_TEMP )
        {
          I22DAT = I2CMasterBuffer[2];
        }
        I22CONCLR = (I2CONCLR_SIC | I2CONCLR_STAC);
        I2CMasterState = I2C_RESTARTED;
        break;

        case 0x18:                      /* Regardless, it's a ACK */
        if ( I2CMasterState == I2C_STARTED )
        {
          I22DAT = I2CMasterBuffer[1+WrIndex];
          WrIndex++;
          I2CMasterState = DATA_ACK;
        }
        I22CONCLR = I2CONCLR_SIC;
        break;

        case 0x28:      /* Data char has been transmitted, regardless ACK or NACK */
        case 0x30:
        if ( WrIndex != I2CWriteLength )
        {
          I22DAT = I2CMasterBuffer[1+WrIndex]; /* this should be the last one */
          WrIndex++;
          if ( WrIndex != I2CWriteLength )
          {
                I2CMasterState = DATA_ACK;
          }
          else
          {
                I2CMasterState = DATA_NACK;
                if ( I2CReadLength != 0 )
                {
                  I22CONSET = I2CONSET_STA;     /* Set Repeated-start flag */
                  I2CMasterState = I2C_REPEATED_START;
                }
          }
        }
        else
        {
          if ( I2CReadLength != 0 )
          {
                I22CONSET = I2CONSET_STA;       /* Set Repeated-start flag */
                I2CMasterState = I2C_REPEATED_START;
          }
          else
          {
                I2CMasterState = DATA_NACK;
                I22CONSET = I2CONSET_STO;      /* Set Stop flag */
          }
        }
        I22CONCLR = I2CONCLR_SIC;
        break;

        case 0x40:      /* Master Receive, SLA_R has been sent */
        I22CONSET = I2CONSET_AA;        /* assert ACK after data is received */
        I22CONCLR = I2CONCLR_SIC;
        break;

        case 0x50:      /* Data char has been received, regardless following ACK or NACK */
        case 0x58:
        I2CMasterBuffer[3+RdIndex] = I22DAT;
        RdIndex++;
        if ( RdIndex != I2CReadLength )
        {
          I2CMasterState = DATA_ACK;
        }
        else
        {
          RdIndex = 0;
          I2CMasterState = DATA_NACK;
        }
        I22CONSET = I2CONSET_AA;        /* assert ACK after data is received */
        I22CONCLR = I2CONCLR_SIC;
        break;

        case 0x20:              /* regardless, it's a NACK */
        case 0x48:
        I22CONCLR = I2CONCLR_SIC;
        I2CMasterState = DATA_NACK;
        break;

        case 0x38:              /* Arbitration lost, in this example, we don't
                                        deal with multiple master situation */
        default:
        I22CONCLR = I2CONCLR_SIC;
        break;
  }
  VICVectAddr = 0;              /* Acknowledge Interrupt */
}