open-story-teller/firmware/cpu/atmel-samd21/adc.c

77 lines
3 KiB
C

/*
* Copyright (c) 2016, Alex Taradov <alex@taradov.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. The name of the author may not 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.
*/
/*- Includes ----------------------------------------------------------------*/
#include <stdlib.h>
#include <stdint.h>
#include <stdbool.h>
#include "samd21.h"
#include "hal_gpio.h"
#include "nvm_data.h"
#include "dac.h"
/*- Definitions -------------------------------------------------------------*/
HAL_GPIO_PIN(ADC, A, 3)
/*- Implementations ---------------------------------------------------------*/
//-----------------------------------------------------------------------------
void adc_init(void)
{
HAL_GPIO_ADC_in();
HAL_GPIO_ADC_pmuxen(HAL_GPIO_PMUX_B);
PM->APBCMASK.reg |= PM_APBCMASK_ADC;
GCLK->CLKCTRL.reg = GCLK_CLKCTRL_ID(ADC_GCLK_ID) |
GCLK_CLKCTRL_CLKEN | GCLK_CLKCTRL_GEN(0);
ADC->CTRLA.reg = ADC_CTRLA_SWRST;
while (ADC->CTRLA.reg & ADC_CTRLA_SWRST);
ADC->REFCTRL.reg = ADC_REFCTRL_REFSEL_INTVCC1 | ADC_REFCTRL_REFCOMP;
ADC->CTRLB.reg = ADC_CTRLB_RESSEL_16BIT | ADC_CTRLB_PRESCALER_DIV32;
ADC->AVGCTRL.reg = ADC_AVGCTRL_SAMPLENUM_128;
ADC->INPUTCTRL.reg = ADC_INPUTCTRL_MUXPOS_PIN1 | ADC_INPUTCTRL_MUXNEG_GND |
ADC_INPUTCTRL_GAIN_DIV2;
ADC->CALIB.reg = ADC_CALIB_BIAS_CAL(NVM_READ_CAL(ADC_BIASCAL)) |
ADC_CALIB_LINEARITY_CAL(NVM_READ_CAL(ADC_LINEARITY));
ADC->CTRLA.reg = ADC_CTRLA_ENABLE;
}
//-----------------------------------------------------------------------------
int adc_read(void)
{
ADC->SWTRIG.reg = ADC_SWTRIG_START;
while (0 == (ADC->INTFLAG.reg & ADC_INTFLAG_RESRDY));
return ADC->RESULT.reg;
}