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106 lines
2.5 KiB
C
106 lines
2.5 KiB
C
/*
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* Copyright (C) 2016-2017 Bas Stottelaar <basstottelaar@gmail.com>
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*
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* This file is subject to the terms and conditions of the GNU Lesser
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* General Public License v2.1. See the file LICENSE in the top level
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* directory for more details.
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*/
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/**
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* @ingroup cpu_efm32
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* @ingroup drivers_periph_adc
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* @{
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*
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* @file
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* @brief Low-level ADC driver implementation
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*
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* @author Bas Stottelaar <basstottelaar@gmail.com>
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*
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* @}
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*/
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#include <assert.h>
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#include "cpu.h"
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#include "mutex.h"
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#include "periph_conf.h"
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#include "periph/adc.h"
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#include "em_cmu.h"
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#include "em_adc.h"
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static mutex_t adc_lock[ADC_DEV_NUMOF];
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int adc_init(adc_t line)
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{
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/* check if line is valid */
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if (line >= ADC_NUMOF) {
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return -1;
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}
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uint8_t dev = adc_channel_config[line].dev;
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assert(dev < ADC_DEV_NUMOF);
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/* initialize lock */
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mutex_init(&adc_lock[dev]);
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/* enable clock */
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CMU_ClockEnable(cmuClock_HFPER, true);
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CMU_ClockEnable(adc_config[dev].cmu, true);
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/* reset and initialize peripheral */
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ADC_Init_TypeDef init = ADC_INIT_DEFAULT;
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init.timebase = ADC_TimebaseCalc(0);
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init.prescale = ADC_PrescaleCalc(400000, 0);
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ADC_Reset(adc_config[dev].dev);
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ADC_Init(adc_config[dev].dev, &init);
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return 0;
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}
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int32_t adc_sample(adc_t line, adc_res_t res)
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{
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/* resolutions larger than 12 bits are not supported */
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if (res >= ADC_MODE_UNDEF(0)) {
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return -1;
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}
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uint8_t dev = adc_channel_config[line].dev;
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/* lock device */
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mutex_lock(&adc_lock[dev]);
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/* setup channel */
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ADC_InitSingle_TypeDef init = ADC_INITSINGLE_DEFAULT;
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init.acqTime = adc_channel_config[line].acq_time;
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init.reference = adc_channel_config[line].reference;
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init.resolution = (ADC_Res_TypeDef) (res & 0x0F);
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#if defined(_SILICON_LABS_32B_SERIES_0)
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init.input = adc_channel_config[line].input;
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#elif defined(_SILICON_LABS_32B_SERIES_1)
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init.posSel = adc_channel_config[line].input;
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#endif
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ADC_InitSingle(adc_config[dev].dev, &init);
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/* start conversion and block until it completes */
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ADC_Start(adc_config[dev].dev, adcStartSingle);
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while ((adc_config[dev].dev->STATUS & ADC_STATUS_SINGLEDV) == 0);
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int result = ADC_DataSingleGet(adc_config[dev].dev);
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/* for resolutions that are not really supported, shift the result (for
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instance, 10 bit resolution is achieved by shifting a 12 bit sample). */
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result = result >> (res >> 4);
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/* unlock device */
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mutex_unlock(&adc_lock[dev]);
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return result;
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}
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