contiki/cpu/cc2538/dev/adc.c

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/*
* Copyright (c) 2013, ADVANSEE - http://www.advansee.com/
* Benoît Thébaudeau <benoit.thebaudeau@advansee.com>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. 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.
*
* 3. Neither the name of the copyright holder nor the names of its
* 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 HOLDER 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.
*/
/**
* \addtogroup cc2538-adc
* @{
*
* \file
* Implementation of the cc2538 ADC driver
*/
#include "contiki.h"
#include "dev/soc-adc.h"
#include "dev/cctest.h"
#include "dev/rfcore-xreg.h"
#include "dev/adc.h"
#include "reg.h"
#include <stdint.h>
/*---------------------------------------------------------------------------*/
void
adc_init(void)
{
/* Start conversions only manually */
REG(SOC_ADC_ADCCON1) |= SOC_ADC_ADCCON1_STSEL;
}
/*---------------------------------------------------------------------------*/
int16_t
adc_get(uint8_t channel, uint8_t ref, uint8_t div)
{
uint32_t cctest_tr0, rfcore_xreg_atest;
int16_t res;
/* On-chip temperature sensor */
if(channel == SOC_ADC_ADCCON_CH_TEMP) {
/* Connect the temperature sensor to the ADC */
cctest_tr0 = REG(CCTEST_TR0);
REG(CCTEST_TR0) = cctest_tr0 | CCTEST_TR0_ADCTM;
/* Enable the temperature sensor */
rfcore_xreg_atest = REG(RFCORE_XREG_ATEST);
REG(RFCORE_XREG_ATEST) = (rfcore_xreg_atest & ~RFCORE_XREG_ATEST_ATEST_CTRL) |
RFCORE_XREG_ATEST_ATEST_CTRL_TEMP;
}
/* Start a single extra conversion with the given parameters */
REG(SOC_ADC_ADCCON3) = (REG(SOC_ADC_ADCCON3) &
~(SOC_ADC_ADCCON3_EREF | SOC_ADC_ADCCON3_EDIV | SOC_ADC_ADCCON3_ECH)) |
ref | div | channel;
/* Poll until end of conversion */
while(!(REG(SOC_ADC_ADCCON1) & SOC_ADC_ADCCON1_EOC));
/* Read conversion result, reading SOC_ADC_ADCH last to clear
* SOC_ADC_ADCCON1.EOC */
res = REG(SOC_ADC_ADCL) & 0xfc;
res |= REG(SOC_ADC_ADCH) << 8;
/* On-chip temperature sensor */
if(channel == SOC_ADC_ADCCON_CH_TEMP) {
/* Restore the initial temperature sensor state and connection (better for
* power consumption) */
REG(RFCORE_XREG_ATEST) = rfcore_xreg_atest;
REG(CCTEST_TR0) = cctest_tr0;
}
/* Return conversion result */
return res;
}
/** @} */