reflow-oven-control-sw/stm-firmware/include/reflow-controller/adc-meas.h

/* Reflow Oven Controller
 *
 * Copyright (C) 2020  Mario Hüttel <mario.huettel@gmx.net>
 *
 * This file is part of the Reflow Oven Controller Project.
 *
 * The reflow oven controller is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * GDSII-Converter 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 the reflow oven controller project.
 * If not, see <http://www.gnu.org/licenses/>.
 */

/**
 * @file adc-meas.h
 */

#ifndef __ADCMEAS_H__
#define __ADCMEAS_H__

#include <stdbool.h>
#include <stdint.h>
#include <stm32/stm32f4xx.h>

/*If this is changed, change DMA code to fit the channel assignment! */
#define ADC_PT1000_PERIPH ADC3
#define ADC_PT1000_DMA2_STREAM0_CHANNEL 2

/**
 * @brief Moving average filter coefficient for PT1000 measurement
 */
#define ADC_PT1000_FILTER_WEIGHT 0.005f

/**
  * @brief Moving average filter weight used for fast regaulation. This is used when the measured resistance
  * is more than 20 Ohms away from the current averaged value.
  */
#define ADC_PT1000_FILTER_WEIGHT_FAST 0.05

/**
 * @brief Difference in Ohm between filter input and output that determines if the filter is stable or unstable.
 */
#define ADC_PT1000_FILTER_UNSTABLE_DIFF 20

/**
 * @brief Sample count, the moving average filter has to be within @ref ADC_PT1000_FILTER_UNSTABLE_DIFF for the filter
 * to be considered stable
 */
#define ADC_PT1000_FILTER_STABLE_SAMPLE_COUNT 200

/**
 * @brief ADC channel number of PT1000 sensor input
 */
#define ADC_PT1000_CHANNEL 2U

/**
 * @brief GPIO Port the ADC converter for the PT1000 measurement is connected to
 */
#define ADC_PT1000_PORT GPIOA

/**
 * @brief The clock enable mask of the RCC register for ADC_PT1000_PORT
 */
#define ADC_PT1000_PORT_RCC_MASK RCC_AHB1ENR_GPIOAEN

/**
 * @brief The GPIO pin number the PT1000 analog voltage is connected to
 */
#define ADC_PT1000_PIN 2U

/**
 * @brief The delay value programmed into the sample timer
 */
#define ADC_PT1000_SAMPLE_CNT_DELAY 1000U

/**
 * @brief The amount of samples to take to prefilter the analog signal
 */
#define ADC_PT1000_DMA_AVG_SAMPLES 6U

/**
 * @brief Lower value for valid input range for PT1000 measurement
 *
 * If the input of the PT1000 sensor is below this value, an error is thrown. This is used to disable the temperature control loop
 */
#define ADC_PT1000_LOWER_WATCHDOG 200U

/**
 * @brief Upper value for valid input range for PT1000 measurement
 *
 * If the input of the PT1000 sensor is above this value, an error is thrown. This is used to disable the temperature control loop
 */
#define ADC_PT1000_UPPER_WATCHDOG 4000U

/**
 * @brief Number of ADC samples the value has to be outside the Watchdog limit (@ref ADC_PT1000_UPPER_WATCHDOG and @ref ADC_PT1000_LOWER_WATCHDOG)
 * in order to produce a watchdog error
 */
#define ADC_PT1000_WATCHDOG_SAMPLE_COUNT 25U

/**
 * @brief Conversion macro: ADC value to resistance
 */
#define ADC_TO_RES(adc) ((float)(adc) / 4096.0f * 2500.0f)

#define RES_TO_ADC(res) ((float)(res) / 2500.0f * 4096.0f)

/**
 * @brief This function sets up the ADC measurement fo the external PT1000 temperature sensor
 *
 * Used peripherals:
 * - Timer 2 for sampling control
 * - ADC1
 *
 * The filter weight \f$\alpha\f$ is configured for @ref ADC_PT1000_FILTER_WEIGHT
 *
 */
void adc_pt1000_setup_meas(void);

/**
 * @brief Set moving average filter parameters
 *
 * The sampled resistance value is filtered with an exponential average filter
 * specified by following difference equation:
 *
 * \f$ y[n] = (1-\alpha)y[n-1] + \alpha x[n] \f$
 *
 * @param alpha
 */
void adc_pt1000_set_moving_average_filter_param(float alpha);

/**
 * @brief Set the calibration data for the PT1000 measurement
 *
 * The resulting resistance reading is
 * \f$R_{corrected} = (1 + \sigma) R_{raw} + O\f$
 *
 * @param offset Offset \f$O\f$
 * @param sensitivity_deviation Sensitivity Deviation \f$\sigma\f$ after offset correction
 * @param active Calibration is active
 */
void adc_pt1000_set_resistance_calibration(float offset, float sensitivity_deviation, bool active);

/**
 * @brief Get the state and values of the resistance calibration
 * @param offset Offset
 * @param sensitivity_deviation Sensitivity deviation
 * @param active Active state of the correction
 */
void adc_pt1000_get_resistance_calibration(float *offset, float *sensitivity_deviation, bool *active);

/**
 * @brief Get the current resistance value
 *
 * If the resistance calibration is enabled, this function applies the calculations of the raw resistance reading and
 * returns the corrected value.
 *
 * If an ADC error is set, the status is negative. The status is 2 during the first measurements with a given filter setting. Technically, the resistance value is
 * correct but the filter is not stable yet.
 *
 * @param[out] resistance Resistance output in Ohms
 * @return Status
 */
int adc_pt1000_get_current_resistance(float *resistance);

/**
 * @brief Stream the raw ADC data to an array in memory.
 * @param adc_array Array to stream data to
 * @param length Amount of data points to be measured
 * @param flag_to_set This flag is set to 1 once the data has been measured and is transferred. A negative value indicates an error
 * @return 0 if measurement could be started
 */
int adc_pt1000_stream_raw_value_to_memory(volatile float *adc_array, uint32_t length, volatile int *flag_to_set);

/**
 * @brief Convert an array of raw adc values to resistance values
 *
 * In case \p resistance_dest is NULL, the conversion is done inplace in the
 * \p raw_source array.
 *
 * @param resistance_dest Destination. Maybe NULL.
 * @param raw_source Source array
 * @param count Number of values to convert
 */
void adc_pt1000_convert_raw_value_array_to_resistance(float *resistance_dest, float *raw_source, uint32_t count);

/**
 * @brief Disable the PT1000 measurement
 */
void adc_pt1000_disable(void);

#endif // __ADCMEAS_H__