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cpu/stm32f1/adc: Initial import for STM32F1 ADC
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/* | ||
* Copyright (C) 2016 Engineering-Spirit | ||
* | ||
* 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. | ||
*/ | ||
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/** | ||
* @ingroup cpu_stm32f1 | ||
* @{ | ||
* | ||
* @file | ||
* @brief Low-level ADC driver implementation | ||
* | ||
* @author Hauke Petersen <hauke.petersen@fu-berlin.de> | ||
* @author Nick van IJzendoorn <nijzendoorn@engineering-spirit.nl> | ||
* | ||
* @} | ||
*/ | ||
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#include "cpu.h" | ||
#include "mutex.h" | ||
#include "periph/adc.h" | ||
#include "periph_conf.h" | ||
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/** | ||
* @brief Maximum allowed ADC clock speed | ||
*/ | ||
#define MAX_ADC_SPEED (14000000U) | ||
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/** | ||
* @brief Load the ADC configuration | ||
* @{ | ||
*/ | ||
#ifdef ADC_CONFIG | ||
static const adc_conf_t adc_config[] = ADC_CONFIG; | ||
#else | ||
static const adc_conf_t adc_config[] = {}; | ||
#endif | ||
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/** | ||
* @brief Allocate locks for all three available ADC devices | ||
*/ | ||
static mutex_t locks[] = { | ||
#if ADC_DEVS > 1 | ||
MUTEX_INIT, | ||
#endif | ||
#if ADC_DEVS > 2 | ||
MUTEX_INIT, | ||
#endif | ||
MUTEX_INIT | ||
}; | ||
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static inline ADC_TypeDef *dev(adc_t line) | ||
{ | ||
return (ADC_TypeDef *)(ADC1_BASE + (adc_config[line].dev << 8)); | ||
} | ||
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static inline void prep(adc_t line) | ||
{ | ||
mutex_lock(&locks[adc_config[line].dev]); | ||
RCC->APB2ENR |= (RCC_APB2ENR_ADC1EN << adc_config[line].dev); | ||
} | ||
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static inline void done(adc_t line) | ||
{ | ||
RCC->APB2ENR &= ~(RCC_APB2ENR_ADC1EN << adc_config[line].dev); | ||
mutex_unlock(&locks[adc_config[line].dev]); | ||
} | ||
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int adc_init(adc_t line) | ||
{ | ||
uint32_t clk_div = 2; | ||
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/* check if the line is valid */ | ||
if (line >= ADC_NUMOF) { | ||
return -1; | ||
} | ||
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/* lock and power-on the device */ | ||
prep(line); | ||
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/* configure the pin */ | ||
gpio_init_analog(adc_config[line].pin); | ||
/* set clock prescaler to get the maximal possible ADC clock value */ | ||
for (clk_div = 2; clk_div < 8; clk_div += 2) { | ||
if ((CLOCK_CORECLOCK / clk_div) <= MAX_ADC_SPEED) { | ||
break; | ||
} | ||
} | ||
RCC->CFGR &= ~(RCC_CFGR_ADCPRE); | ||
RCC->CFGR |= ((clk_div / 2) - 1) << 14; | ||
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/* enable the ADC module */ | ||
dev(line)->CR2 |= ADC_CR2_ADON; | ||
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/* resets the selected ADC calibration registers */ | ||
dev(line)->CR2 |= ADC_CR2_RSTCAL; | ||
/* check the status of RSTCAL bit */ | ||
while (dev(line)->CR2 & ADC_CR2_RSTCAL) {} | ||
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/* enable the selected ADC calibration process */ | ||
dev(line)->CR2 |= ADC_CR2_CAL; | ||
/* wait for the calibration to have finished */ | ||
while (dev(line)->CR2 & ADC_CR2_CAL) {} | ||
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/* set all channels to maximum (239.5) cycles for best accuracy */ | ||
dev(line)->SMPR1 |= 0x00ffffff; | ||
dev(line)->SMPR2 |= 0x3fffffff; | ||
/* we want to sample one channel */ | ||
dev(line)->SQR1 = ADC_SQR1_L_0; | ||
/* start sampling from software */ | ||
dev(line)->CR2 |= ADC_CR2_EXTTRIG | ADC_CR2_EXTSEL; | ||
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/* check if this channel is an internal ADC channel, if so | ||
* enable the internal temperature and Vref */ | ||
if (adc_config[line].chan == 16 || adc_config[line].chan == 17) { | ||
/* check if the internal channels are configured to use ADC1 */ | ||
if (dev(line) != ADC1) { | ||
return -3; | ||
} | ||
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dev(line)->CR2 |= ADC_CR2_TSVREFE; | ||
} | ||
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/* free the device again */ | ||
done(line); | ||
return 0; | ||
} | ||
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int adc_sample(adc_t line, adc_res_t res) | ||
{ | ||
int sample; | ||
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/* check if the linenel is valid */ | ||
if (line >= ADC_NUMOF) { | ||
return -1; | ||
} | ||
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/* check if resolution is applicable */ | ||
if (res != ADC_RES_12BIT) { | ||
return -2; | ||
} | ||
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/* lock and power on the ADC device */ | ||
prep(line); | ||
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/* set conversion channel */ | ||
dev(line)->SQR3 = adc_config[line].chan; | ||
/* start conversion and wait for results */ | ||
dev(line)->CR2 |= ADC_CR2_SWSTART; | ||
while (!(dev(line)->SR & ADC_SR_EOC)) {} | ||
/* finally read sample and reset the STRT bit in the status register */ | ||
sample = (int)dev(line)->DR; | ||
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/* power off and unlock device again */ | ||
done(line); | ||
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return sample; | ||
} |
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