osd-contiki/platform/avr-ravenlcd/adc.c

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/*
* Copyright (c) 2008 Swedish Institute of Computer Science
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* * Neither the name of the copyright holders nor the names of
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
/**
* \file
*
* \brief
* Functions to control the ADC of the MCU. This is used to read the
* joystick.
*
* \author
* Mike Vidales mavida404@gmail.com
*
*/
#include "adc.h"
/**
* \addtogroup lcd
* \{
*/
static bool adc_initialized;
static bool adc_conversion_started;
/*---------------------------------------------------------------------------*/
/**
* \brief This function will init the ADC with the following parameters.
*
* \param chan Determines the ADC channel to open.
* \param trig Sets what type of trigger is needed.
* \param ref Sets the proper reference voltage.
* \param prescale Sets the prescale to be used against the XTAL choice.
*
* \return 0
*/
int
adc_init(adc_chan_t chan, adc_trig_t trig, adc_ref_t ref, adc_ps_t prescale)
{
/* Enable ADC module */
PRR &= ~(1 << PRADC);
/* Configure */
ADCSRA = (1<<ADEN)|prescale;
ADMUX = (uint8_t)ref|(uint8_t)chan;
ADCSRB = trig;
adc_initialized = true;
adc_conversion_started = false;
return 0;
}
/*---------------------------------------------------------------------------*/
/**
* \brief This will disable the adc.
*/
void
adc_deinit(void)
{
/* Disable ADC */
ADCSRA &= ~(1<<ADEN);
PRR |= (1 << PRADC);
adc_initialized = false;
adc_conversion_started = false;
}
/*---------------------------------------------------------------------------*/
/**
* \brief This will start an ADC conversion
*
* \return 0
*/
int
adc_conversion_start(void)
{
if (adc_initialized == false){
return EOF;
}
adc_conversion_started = true;
ADCSRA |= (1<<ADSC);
return 0;
}
/*---------------------------------------------------------------------------*/
/**
* \brief This will read the ADC result during the ADC conversion and return
* the raw ADC conversion result.
*
* \param adjust This will Left or Right Adjust the ADC conversion result.
*
* \return ADC raw 16-byte ADC conversion result.
*/
int16_t
adc_result_get(adc_adj_t adjust)
{
if (adc_conversion_started == false){
return EOF;
}
if (ADCSRA & (1<<ADSC)){
return EOF;
}
adc_conversion_started = false;
ADMUX |= (adjust<<ADLAR);
return (int16_t)ADC;
}
/** \} */