pcf8574a.c

IT projecotr reference design.

/****************************************************************************/
/*             TEXAS INSTRUMENTS PROPRIETARY INFORMATION                    */
/*                                                                          */
/*  (c) Copyright, Texas Instruments Incorporated, 2006.                    */
/*      All Rights Reserved.                                                */
/*                                                                          */
/*  Property of Texas Instruments Incorporated. Restricted Rights -         */
/*  Use, duplication, or disclosure is subject to restrictions set          */
/*  forth in TI's program license agreement and associated documentation.   */
/****************************************************************************/

/****************************************************************************/
/* pcf8574a.c                                                               */
/*                                                                          */
/* 8-Bit IO expander device driver.                                         */
/****************************************************************************/

#include "common.h"
#include "ddp2230_rtos_include.h"
#include "tmr.h"
#include "i2c.h"

#include "ioExpander.h"

                        /****************************************************/
                        /* Local constants and definitions.                 */
                        /****************************************************/

#define DEVBASE      0x38                   /* unshifted i2c device address */
#define PINPERCHIP      8                     /* number of IO pins per chip */

                        /****************************************************/
                        /* Local data.                                      */
                        /****************************************************/

static int32   semTicks;                   /* semaphore acquisition timeout */
static uint32  semID;                       /* IO expander i2c semaphore ID */
static I2CPORT iPort;                           /* ASIC i2c controller port */

static IOXCC _ccTestRtn( int08 APIcc );



/****************************************************************************/
/* Open the IOX device driver.                                              */
/*                                                                          */
/* All pins are programmed to inputs. This is done to ensure the device is  */
/* in a known state during debug. This is not necessary in production code  */
/* since a power-up automatically configures the pins.                      */
/****************************************************************************/

IOXCC ioxdd_open( IOXINITSTRUCT *pInit )
{
    iPort    = pInit -> xPort;                           /* i2c port number */
    semTicks = TMR_ConvertMSToTicks(  pInit -> xTimeout );  /* tick timeout */
    I2C_GetSemaphoreID( iPort, &semID);                 /* i2c semaphore ID */
    
    return IOXCC_PASS;
}



/****************************************************************************/
/* Configure a pcf8574a pin.                                                */
/****************************************************************************/

IOXCC ioxdd_configPin( uint08 pinCfg )
{
                        /****************************************************/
                        /* If configuring as an input, set the pin output   */
                        /* driver high, which allows an incoming signal to  */
                        /* drive the pin high or low.                       */
                        /****************************************************/

    if( IOX_IN == IOX_GETDIR( pinCfg ))
    {
        ioxDirection |= ( 0x00000001 << IOX_GETPIN( pinCfg ));
        return ioxdd_drivePin( IOX_GETPIN( pinCfg ), TRUE );
    }
    
                        /****************************************************/
                        /* If configuring as an output, set the pin output  */
                        /* driver to the indicated state.                   */
                        /****************************************************/

    else
    {
        ioxDirection &= ~( 0x00000001 << IOX_GETPIN( pinCfg ));
        return ioxdd_drivePin( IOX_GETPIN( pinCfg ), IOX_GETVAL( pinCfg ));
    }
}



/****************************************************************************/
/* Drive a pcf8574a pin to the indicated state.                             */
/*                                                                          */
/* pcf8574a pin register is 8 bits wide.                                    */
/****************************************************************************/

IOXCC ioxdd_drivePin( int08 pin, BOOL state )
{
    int08  cc;                                       /* API completion code */
    
    int08  chipNo;
    uint08 chipRegister;
    uint32 numTran;

    if( state )
        ioxState |=  ( 0x00000001 << pin );
    else
        ioxState &= ~( 0x00000001 << pin );
    
    if( RTA_SUCCESS != RTA_SemReserve( semID, semTicks ))
        return IOXCC_FAIL;

    chipNo       = pin / PINPERCHIP;
    chipRegister = (uint08)( 0xff & ( ioxState >> ( chipNo * PINPERCHIP )));
    
    cc = I2C_MasterWrite
         ( 
            iPort, ( DEVBASE + chipNo ) << 1, 1, 
            &chipRegister, 0, 0, &numTran 
         );

    return _ccTestRtn( cc );
}



/****************************************************************************/
/* Read a PCF8574A pin.                                                     */
/*                                                                          */
/* PCF8574A pin register is 8 bits wide.                                    */
/****************************************************************************/

IOXCC ioxdd_readPin( int08 pin, BOOL *state )
{
    int08  cc;                                       /* API completion code */
    
    int08  chipNo;
    uint08 chipRegister;
    uint32 numTran;

    if( RTA_SUCCESS != RTA_SemReserve( semID, semTicks ))
        return IOXCC_FAIL;

    chipNo = pin / PINPERCHIP;
    
    cc = I2C_MasterRead
         ( 
           iPort,                                                   /* Port */
           ( DEVBASE + chipNo ) << 1,                      /* DeviceAddress */
           1,                                                 /* NumOfBytes */
           &chipRegister,                                    /* *ReadBuffer */
           1,                                                  /* ByteDelay */
           0,                                                    /* Timeout */
           &numTran                                           /* *BytesRead */
         );

   *state = 0x01 & ( chipRegister >> ( pin & 0x07 ));
   
    return _ccTestRtn( cc );
}



/****************************************************************************/
/* Return device type.                                                      */
/****************************************************************************/

IOXTYPE ioxdd_type( void )
{
    return IOXTYPE_PCF8574A;
}



/****************************************************************************/
/* Test completion code and reset i2c configuration on error.               */
/*                                                                          */
/* This function is called when exiting any function that has reserved the  */
/* i2c semaphore. An API completion code is passed in and examined for      */
/* error. If an error is seen, the port is reset.                           */
/****************************************************************************/

static IOXCC _ccTestRtn( int08 APIcc )
{
    I2CINIT saveConfig;                           /*saved i2c configuration */

    if( PASS != APIcc )                         /* if an API error occurred */
    {
        I2C_GetConfig( iPort, &saveConfig );
        I2C_Reset( iPort );
        I2C_SetConfig( iPort, &saveConfig );
    }

    RTA_SemRelease( semID );
    
    return ( PASS == APIcc ) ? IOXCC_PASS : IOXCC_APIERROR;
}