77 lines
2.9 KiB
C
77 lines
2.9 KiB
C
/***************************************************************************
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* Copyright (C) 2020 by Silvano Seva IU2KWO and Niccolò Izzo IU2KIN *
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* *
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* This program is free software; you can redistribute it and/or modify *
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* it under the terms of the GNU General Public License as published by *
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* the Free Software Foundation; either version 3 of the License, or *
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* (at your option) any later version. *
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* *
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* This program is distributed in the hope that it will be useful, *
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* but WITHOUT ANY WARRANTY; without even the implied warranty of *
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
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* GNU General Public License for more details. *
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* *
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* You should have received a copy of the GNU General Public License *
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* along with this program; if not, see <http://www.gnu.org/licenses/> *
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***************************************************************************/
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#include <hwconfig.h>
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#include "ADC0_GDx.h"
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void adc0_init()
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{
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SIM->SCGC6 |= SIM_SCGC6_ADC0(1);
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ADC0->CFG1 |= ADC_CFG1_ADIV(3) /* Divide clock by 8 */
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| ADC_CFG1_ADLSMP(1) /* Long sample time */
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| ADC_CFG1_MODE(3); /* 16 bit result */
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ADC0->SC3 |= ADC_SC3_AVGE(1) /* Enable hardware average */
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| ADC_SC3_AVGS(3); /* Average over 32 samples */
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/* Calibrate ADC */
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ADC0->SC3 |= ADC_SC3_CAL(1);
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while((ADC0->SC3) & ADC_SC3_CAL_MASK) ;
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uint32_t cal = ADC0->CLP0
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+ ADC0->CLP1
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+ ADC0->CLP2
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+ ADC0->CLP3
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+ ADC0->CLP4
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+ ADC0->CLPS;
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ADC0->PG = 0x8000 | (cal >> 1);
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}
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void adc0_terminate()
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{
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SIM->SCGC6 &= ~SIM_SCGC6_ADC0(1);
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}
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uint16_t adc0_getRawSample(uint8_t ch)
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{
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if(ch > 32) return 0;
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/* Conversion is automatically initiated by writing to this register */
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ADC0->SC1[0] = ADC_SC1_ADCH(ch);
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while(((ADC0->SC1[0]) & ADC_SC1_COCO_MASK) == 0) ;
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return ADC0->R[0];
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}
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uint16_t adc0_getMeasurement(uint8_t ch)
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{
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/*
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* To avoid using floats, we convert the raw ADC sample to mV using 16.16
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* fixed point math. The equation for conversion is (sample * 3300)/4096 but,
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* since converting the raw ADC sample to 16.16 notation requires a left
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* shift by 16 and dividing by 4096 is equivalent to shifting right by 12,
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* we just shift left by four and then multiply by 3300.
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* With respect to using floats, maximum error is -1mV.
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*/
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uint32_t sample = (adc0_getRawSample(ch) << 4) * 3300;
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return ((uint16_t) (sample >> 16));
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}
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