library

/*! \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);
}