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73 lines
1.8 KiB
C
73 lines
1.8 KiB
C
/*
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* Copyright (C) 2018 Eistec AB
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* Copyright (C) 2015 Freie Universität Berlin
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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 sys_analog_util
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* @{
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*
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* @file
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* @brief ADC utility function implementation
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*
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* @author Hauke Petersen <hauke.petersen@fu-berlin.de>
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* @author Joakim Nohlgård <joakim.nohlgard@eistec.se>
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*
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* @}
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*/
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#include <stdint.h>
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#include <inttypes.h>
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#include "cpu.h"
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#include "periph/adc.h"
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#include "analog_util.h"
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#include "assert.h"
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#define ENABLE_DEBUG 0
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#include "debug.h"
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/**
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* @brief Convert adc_res_t resolution setting into numeric bit count
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*/
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static unsigned int _adc_res_bits(adc_res_t res)
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{
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switch (res) {
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case ADC_RES_6BIT:
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return 6;
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case ADC_RES_8BIT:
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return 8;
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case ADC_RES_10BIT:
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return 10;
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case ADC_RES_12BIT:
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return 12;
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case ADC_RES_14BIT:
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return 14;
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case ADC_RES_16BIT:
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return 16;
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default:
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/* Unsupported ADC resolution, modify your application to use a
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* different resolution, or add it above */
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assert(0 == 1);
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return 0;
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}
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}
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int32_t adc_util_map(int sample, adc_res_t res, int32_t min, int32_t max)
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{
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/* Using 64 bit signed int as intermediate to prevent overflow when range
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* multiplied by sample requires more than 32 bits */
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int32_t scaled = (((int64_t)(max - min) * sample) >> _adc_res_bits(res));
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DEBUG("scaled: %" PRId32 "\n", scaled);
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return (min + scaled);
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}
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float adc_util_mapf(int sample, adc_res_t res, float min, float max)
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{
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return ((((max - min) * sample) / ((int32_t)1L << _adc_res_bits(res))) + min);
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}
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