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/* *****************************************************************************
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* Created: 12/18/09 02:34:47
* Copyright (c) 2009 Perry L. Hung. All rights reserved.
*
* ****************************************************************************/
/**
* @file adc.c
*
* @brief Analog to digital converter routines
*/
#include "libmaple.h"
#include "rcc.h"
#include "adc.h"
/* The ADC input clock is generated from PCLK2/APB2 divided by a prescaler
* and it must not exceed 14MHz.
*
* ADC1 and ADC2 are clocked by APB2
*
* 1) Power on by setting ADON in ADC_CR2
* Conversion starts when ADON is set for a second time after some
* time t > t_stab.
*
* Up to 16 selected conversion must be selected in ADC_SQRx
*
* Single conversion mode:
* Set the ADON bit in the ADC_CR2 register
* Once the conversion is complete:
* Converted data is stored in ADC_DR
* EOC flag is set
* Interrupt is generated if EOCIE is set
*
* Calibration:
* Calibration is started by setting the CAL bit in the ADC_CR2 register.
* Once calibration is over, the CAL bit is reset by hardware and normal
* conversion can be performed. Calibrate at power-on.
*
* ALIGN in ADC_CR2 selects the alignment of data
*
* 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*/
void adc_init(void) {
rcc_set_adc_prescaler(PCLK2_DIV_2);
rcc_enable_clk_adc1();
rcc_reset_adc1();
ADC_CR1 = 0;
ADC_CR2 = CR2_EXTSEL_SWSTART | CR2_EXTTRIG; // Software triggers conversions
ADC_SQR1 = 0;
/* Up the sample conversion time to 55.5 cycles/sec, see note above */
/* TODO: fix magic numbers */
ADC_SMPR1 = 0xB6DB6D;
ADC_SMPR2 = 0x2DB6DB6D;
/* Enable the ADC */
CR2_ADON_BIT = 1;
/* Reset the calibration registers and then perform a reset */
CR2_RSTCAL_BIT = 1;
while(CR2_RSTCAL_BIT)
;
CR2_CAL_BIT = 1;
while(CR2_CAL_BIT)
;
}
void adc_disable(void) {
CR2_ADON_BIT = 0;
}
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