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/******************************************************************************
* The MIT License
*
* Copyright (c) 2010 Perry Hung.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*****************************************************************************/
/**
* @file adc.c
*
* @brief Analog to digital converter routines
*
* IMPORTANT: maximum external impedance must be below 0.4kOhms for 1.5
* sample conversion time.
*
* At 55.5 cycles/sample, the external input impedance < 50kOhms.
*
* See STM32 manual RM0008 for how to calculate this.
*/
#include "libmaple.h"
#include "rcc.h"
#include "adc.h"
adc_dev adc1 = {
.regs = ADC1_BASE,
.clk_id = RCC_ADC1
};
const adc_dev *ADC1 = &adc1;
adc_dev adc2 = {
.regs = ADC2_BASE,
.clk_id = RCC_ADC2
};
const adc_dev *ADC2 = &adc2;
#ifdef STM32_HIGH_DENSITY
adc_dev adc3 = {
.regs = ADC3_BASE,
.clk_id = RCC_ADC3
};
const adc_dev *ADC3 = &adc3;
#endif
static void adc_calibrate(const adc_dev *dev);
/**
* @brief Initialize an ADC peripheral. Only supports software triggered
* conversions.
* @param dev ADC peripheral to initialize
* @param flags unused
*/
void adc_init(const adc_dev *dev, uint32 flags) {
/* Spin up the clocks */
rcc_set_prescaler(RCC_PRESCALER_ADC, RCC_ADCPRE_PCLK_DIV_6);
rcc_clk_enable(dev->clk_id);
rcc_reset_dev(dev->clk_id);
/* Software triggers conversions, conversion on external events */
adc_set_extsel(dev, 7);
adc_set_exttrig(dev, 1);
/* Enable the ADC */
adc_enable(dev);
/* Calibrate ADC */
adc_calibrate(dev);
}
/**
* @brief Set external event select for regular group
* @param dev adc device
* @param trigger event to select. See ADC_CR2 EXTSEL[2:0] bits.
*/
void adc_set_extsel(const adc_dev *dev, uint8 trigger) {
uint32 cr2 = dev->regs->CR2;
cr2 &= ~ADC_CR2_EXTSEL;
cr2 |= (trigger & 0x7) << 17;
dev->regs->CR2 = cr2;
}
/**
* @brief Turn the given sample rate into values for ADC_SMPRx. Don't
* call this during conversion.
* @param dev adc device
* @param smp_rate sample rate to set
* @see adc_smp_rate
*/
void adc_set_sample_rate(const adc_dev *dev, adc_smp_rate smp_rate) {
uint32 adc_smpr1_val = 0, adc_smpr2_val = 0;
int i;
for (i = 0; i < 10; i++) {
if (i < 8) {
/* ADC_SMPR1 determines sample time for channels [10,17] */
adc_smpr1_val |= smp_rate << (i * 3);
}
/* ADC_SMPR2 determines sample time for channels [0,9] */
adc_smpr2_val |= smp_rate << (i * 3);
}
dev->regs->SMPR1 = adc_smpr1_val;
dev->regs->SMPR2 = adc_smpr2_val;
}
/**
* @brief Calibrate an ADC peripheral
* @param dev adc device
*/
static void adc_calibrate(const adc_dev *dev) {
__io uint32 *rstcal_bit = (__io uint32*)BITBAND_PERI(&(dev->regs->CR2), 3);
__io uint32 *cal_bit = (__io uint32*)BITBAND_PERI(&(dev->regs->CR2), 2);
*rstcal_bit = 1;
while (*rstcal_bit)
;
*cal_bit = 1;
while (*cal_bit)
;
}
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