a752c7ab
 elopes
add first test an...
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/*
* Copyright (C) 2017 HAW Hamburg
*
* This file is subject to the terms and conditions of the GNU Lesser
* General Public License v2.1. See the file LICENSE in the top level
* directory for more details.
*/
/**
* @ingroup cpu_cc2538
* @ingroup drivers_periph_adc
* @{
*
* @file
* @brief Low-level ADC driver implementation
*
* @notice based on TI peripheral drivers library
*
* @author Sebastian Meiling <s@mlng.net>
* @}
*/
#include "board.h"
#include "cpu.h"
#include "periph_conf.h"
#include "periph_cpu.h"
#include "periph/adc.h"
#define ENABLE_DEBUG (0)
#include "debug.h"
int adc_init(adc_t line)
{
if (line >= ADC_NUMOF) {
DEBUG("adc_init: invalid ADC line (%d)!\n", line);
return -1;
}
cc2538_soc_adc_t *adca = SOC_ADC;
/* stop random number generator, and set STSEL = 1 */
adca->cc2538_adc_adccon1.ADCCON1 = 0x3c;
/* disable any DMA, continous ADC settings */
adca->ADCCON2 = 0x0;
/* configure ADC GPIO as analog input */
gpio_init(adc_config[line], IOC_OVERRIDE_ANA);
return 0;
}
int adc_sample(adc_t line, adc_res_t res)
{
/* check if adc line valid */
if (line >= ADC_NUMOF) {
DEBUG("adc_sample: invalid ADC line!\n");
return -1;
}
uint8_t rshift;
/* check if given resolution valid, and set right shift */
switch(res) {
case ADC_RES_7BIT:
rshift = SOCADC_7_BIT_RSHIFT;
break;
case ADC_RES_9BIT:
rshift = SOCADC_9_BIT_RSHIFT;
break;
case ADC_RES_10BIT:
rshift = SOCADC_10_BIT_RSHIFT;
break;
case ADC_RES_12BIT:
rshift = SOCADC_12_BIT_RSHIFT;
break;
default:
DEBUG("adc_sample: invalid resultion!\n");
return -1;
}
/**
* @attention CC2538 ADC supports differential comparision of two analog
* GPIO inputs, hence negative values are possible. RIOT currently allows
* positive ADC output only. Thus, reduce shift by one to compensate and
* get full value range according to ADC resolution. E.g. 10 Bit resultion
* with diff ADC would have [-512,511] range but RIOT expects [0,1023].
*/
rshift--;
cc2538_soc_adc_t *adca = SOC_ADC;
/* configure adc line with parameters and trigger a single conversion*/
uint32_t reg = (adca->ADCCON3) & ~(SOC_ADC_ADCCON3_EREF |
SOC_ADC_ADCCON3_EDIV |
SOC_ADC_ADCCON3_ECH);
adca->ADCCON3 = reg | res | SOC_ADC_ADCCON_REF |
gpio_pp_num(adc_config[line]);
DEBUG("ADCCON1: %"PRIu32" ADCCON2: %"PRIu32" ADCCON3: %"PRIu32"\n",
adca->cc2538_adc_adccon1.ADCCON1, adca->ADCCON2, adca->ADCCON3);
/* Poll/wait until end of conversion */
while ((adca->cc2538_adc_adccon1.ADCCON1 &
SOC_ADC_ADCCON1_EOC_MASK) == 0) {}
/* Read result after conversion completed,
* reading SOC_ADC_ADCH last will clear SOC_ADC_ADCCON1.EOC */
int16_t sample = adca->ADCL & SOC_ADC_ADCL_MASK;
sample |= (adca->ADCH & SOC_ADC_ADCH_MASK) << 8;
/* sample right shifted depending on resolution */
sample = sample >> rshift;
DEBUG("adc_sample: raw value %"PRIi16"\n", sample);
/* FIXME: currently RIOT ADC allows values >0 only */
if (sample < 0) {
sample = 0;
}
return (int)sample;
}
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