ads7870.c

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/*! \file ads7870.c \brief TI ADS7870 12-bit 8ch A/D Converter Driver Library. */
//*****************************************************************************
//
// File Name    : 'ads7870.c'
// Title        : TI ADS7870 12-bit 8ch A/D Converter Driver Library
// Author       : Pascal Stang - Copyright (C) 2005
// Created      : 2005.07.19
// Revised      : 2005.07.21
// 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 "spi.h"
#include "ads7870.h"

// global variables

// Functions
u08 ads7870Init(void)
{
    // initialize spi interface
    spiInit();
    // switch to f/4 bitrate
    cbi(SPCR, SPR0);
    cbi(SPCR, SPR1);
    //sbi(SPSR, SPI2X);

    // setup chip select
    sbi(ADS7870_CS_PORT, ADS7870_CS_PIN);
    sbi(ADS7870_CS_DDR, ADS7870_CS_PIN);

    // check ID register
    if(ads7870ReadReg(ADS7870_ID) != ADS7870_ID_VALUE)
        return 0;

    // setup reference and buffer
    ads7870WriteReg(ADS7870_REFOSC, ADS7870_REFOSC_OSCE | ADS7870_REFOSC_REFE | ADS7870_REFOSC_BUFE);

    // return success
    return 1;
}

s16 ads7870Convert(u08 channel)
{
    // set single-ended channel bit
    channel |= ADS7870_CH_SINGLE_ENDED;
    // do conversion
    return ads7870ConvertRaw(channel);
}

s16 ads7870ConvertDiff(u08 channel)
{
    // clear single-ended channel bit
    channel &= ~ADS7870_CH_SINGLE_ENDED;
    // do conversion
    return ads7870ConvertRaw(channel);
}

s16 ads7870ConvertRaw(u08 channel)
{
    s16 result;
    // assert chip select
    cbi(ADS7870_CS_PORT, ADS7870_CS_PIN);
    // start conversion
    spiTransferByte(ADS7870_CONVERT | channel);
    // wait for completion
    while( ads7870ReadReg(ADS7870_GAINMUX) & ADS7870_GAINMUX_CNVBSY);
    // assert chip select
    cbi(ADS7870_CS_PORT, ADS7870_CS_PIN);
    // read result
    spiTransferByte(ADS7870_REG_READ | ADS7870_REG_16BIT | ADS7870_RESULTHI);
    result  = spiTransferByte(0x00)<<8;
    result |= spiTransferByte(0x00);
    // release chip select
    sbi(ADS7870_CS_PORT, ADS7870_CS_PIN);
    // return result
    return result;
}

u08 ads7870ReadReg(u08 reg)
{
    u08 data;
    // assert chip select
    cbi(ADS7870_CS_PORT, ADS7870_CS_PIN);
    // issue reg read command
    spiTransferByte(ADS7870_REG_READ | reg);
    // read data
    data = spiTransferByte(0x00);
    // release chip select
    sbi(ADS7870_CS_PORT, ADS7870_CS_PIN);
    // return data
    return data;
}

void ads7870WriteReg(u08 reg, u08 value)
{
    // assert chip select
    cbi(ADS7870_CS_PORT, ADS7870_CS_PIN);
    // issue reg write command
    spiTransferByte(ADS7870_REG_WRITE | reg);
    // write data
    spiTransferByte(value);
    // release chip select
    sbi(ADS7870_CS_PORT, ADS7870_CS_PIN);
}

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