ads7828.c

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/*! \file ads7828.c \brief TI ADS7828 12-bit 8ch A/D Converter Driver Library. */
//*****************************************************************************
//
// File Name    : 'ads7828.c'
// Title        : TI ADS7828 12-bit 8ch A/D Converter Driver Library
// Author       : Pascal Stang - Copyright (C) 2004
// Created      : 2004.02.10
// Revised      : 2004.02.19
// Version      : 0.1
// Target MCU   : Atmel AVR Series
// Editor Tabs  : 4
//
// NOTE: This code is currently below version 1.0, and therefore is considered
// to be lacking in some functionality or documentation, or may not be fully
// tested.  Nonetheless, you can expect most functions to work.
//
// This code is distributed under the GNU Public License
//      which can be found at http://www.gnu.org/licenses/gpl.txt
//
//*****************************************************************************

#include <avr/io.h>
#include <avr/interrupt.h>

#include "global.h"
#include "i2c.h"
#include "ads7828.h"

// global variables
u08 Ads7282RefMode;

// Functions
u08 ads7828Init(u08 i2cAddr)
{
    u08 channel = 0x80;

    // setup default A/D voltage reference
    ads7828SetReference(0);

    // issue a convserion to test chip presence
    // return TRUE if chip detected
    // return FALSE if chip does not respond
    return (i2cMasterSendNI(i2cAddr, 1, &channel) == I2C_OK);
}

u16 ads7828Convert(u08 i2cAddr, u08 channel)
{
    // re-order channel bits for
    // logical single-ended channel selection
    // channel bit0 -> C2
    // channel bit1 -> C0
    // channel bit2 -> C1
    channel = (((channel>>1) | (channel&0x01)<<2)<<4) | ADS7828_CMD_SD;
    // do conversion
    return ads7828ConvertRaw(i2cAddr, channel);
}

u16 ads7828ConvertDiff(u08 i2cAddr, u08 channel)
{
    // clear single-ended channel bit
    channel = (channel&0x07)<<4;
    // do conversion
    return ads7828ConvertRaw(i2cAddr, channel);
}

u16 ads7828ConvertRaw(u08 i2cAddr, u08 channel)
{
    u08 buffer[2];
    // combine raw channel and reference bits
    channel &= 0xF0;
    channel |= Ads7282RefMode;
    // start conversion on requested channel
    i2cMasterSendNI(i2cAddr, 1, &channel);
    // retrieve conversion result
    i2cMasterReceiveNI(i2cAddr, 2, buffer);
    // pack bytes and return result
    return ((buffer[0]<<8) | buffer[1]);
}

void ads7828SetReference(u08 ref)
{
    if(ref)
    {
        // use internal reference
        Ads7282RefMode = ADS7828_CMD_PDMODE2;
    }
    else
    {
        // use external reference
        Ads7282RefMode = ADS7828_CMD_PDMODE0;
    }
}

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