reflow-oven-control-sw/stm-firmware/calibration.c

/* 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.
 *
 * The Reflow Oven Control Firmware 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/>.
 */


#include <reflow-controller/calibration.h>
#include <reflow-controller/adc-meas.h>
#include <stm-periph/uart.h>
#include <helper-macros/helper-macros.h>
#include <arm_math.h>
#include <stdlib.h>
#include <float.h>

void calibration_calculate(float low_measured, float low_setpoint, float high_measured, float high_setpoint,
			   float *sens_deviation, float *sens_corrected_offset)
{
	if (!sens_deviation || !sens_corrected_offset)
		return;

	float delta_y;
	float delta_x;
	float sens_corr_mult;

	delta_y = high_measured - low_measured;
	delta_x = high_setpoint - low_setpoint;

	sens_corr_mult = delta_x / delta_y;
	*sens_deviation = sens_corr_mult - 1.0f;

	*sens_corrected_offset = low_setpoint - low_measured * sens_corr_mult;
}



int calibration_acquire_data(float *mu, float *max_dev, uint32_t count)
{
	int status;
	float *stream_mem;
	float min_val = FLT_MAX;
	float max_val = -FLT_MAX;
	uint32_t i;
	int ret_val = 0;

	static volatile int flag = 0;

	if (!mu || !max_dev || !count)
		return -1000;

	stream_mem = (float *)calloc(count, sizeof(float));
	if (!stream_mem)
		return -2;

	status = adc_pt1000_stream_raw_value_to_memory(stream_mem, count, &flag);
	if (status)
		return status;

	/* Wait for data to be transferred */
	while (flag == 0);

	if (flag != 1) {
		/* Error */
		ret_val = -1;
		goto ret_free_mem;
	}

	/* Convert the stream memory to Ohm readings */
	adc_pt1000_convert_raw_value_array_to_resistance(NULL, stream_mem, count);

	/* Do not compute std-deviation. Too imprecise
	 * arm_std_f32(stream_mem, count, sigma);
	 */
	arm_mean_f32(stream_mem, count, mu);

	/* Find min and max values of array */
	for (i = 0U; i < count; i++) {
		min_val = MIN(min_val, stream_mem[i]);
		max_val = MAX(max_val, stream_mem[i]);
	}

	/* Compute maximum deviation range */
	*max_dev = max_val - min_val;

ret_free_mem:
	free(stream_mem);
	return ret_val;
}

static void wait_for_uart_enter()
{
	int enter_received = 0;
	const char *recv_data;
	size_t recv_len;
	size_t iter;
	int uart_recv_status;

	do {
		uart_recv_status = uart_receive_data_with_dma(&recv_data, &recv_len);
		if (uart_recv_status >= 1) {
			for (iter = 0; iter < recv_len; iter++) {
				if (recv_data[iter] == '\n' || recv_data[iter] == '\r')
					enter_received = 1;
			}
		}
	} while (enter_received == 0);
}

int calibration_sequence_shell_cmd(shellmatta_handle_t shell)
{
	float mu, mu2, dev, dev2;
	float sens_dev, offset;

	/* Clear errors of PT1000 reading */
	adc_pt1000_clear_error();

	shellmatta_printf(shell, "Starting calibration: Insert 1000 Ohm calibration resistor and press ENTER\r\n");
	wait_for_uart_enter();
	shellmatta_printf(shell, "Measurement...\r\n");

	/* Clear errors of PT1000 reading */
	adc_pt1000_clear_error();
	calibration_acquire_data(&mu, &dev, 512UL);
	shellmatta_printf(shell, "R=%.2f, Noise peak-peak: %.2f\r\n", mu, dev);
	if (adc_pt1000_check_error() != ADC_PT1000_NO_ERR) {
		shellmatta_printf(shell, "Error in resistance measurement: %d", adc_pt1000_check_error());
		return -1;
	}

	/* Measure 2nd calibration point */
	shellmatta_printf(shell, "Insert 2000 Ohm calibration resistor and press ENTER\r\n");
	wait_for_uart_enter();
	shellmatta_printf(shell, "Measurement...\r\n");

	/* Clear errors of PT1000 reading */
	adc_pt1000_clear_error();
	calibration_acquire_data(&mu2, &dev2, 512UL);
	shellmatta_printf(shell, "R=%.2f, Noise peak-peak: %.2f\r\n", mu2, dev2);
	if (adc_pt1000_check_error() != ADC_PT1000_NO_ERR) {
		shellmatta_printf(shell, "Error in resistance measurement: %d", adc_pt1000_check_error());
		return -2;
	}

	/* Check noise values */
	if (dev > CALIBRATION_MAX_PEAK_PEAK_NOISE_OHM || dev2 > CALIBRATION_MAX_PEAK_PEAK_NOISE_OHM) {
		shellmatta_printf(shell, "Calibration failed! Too much noise. Check you're hardware.\r\n");
		return -3;
	}

	/* Calculate calibration */
	calibration_calculate(mu, 1000.0f, mu2, 2000.0f, &sens_dev, &offset);

	shellmatta_printf(shell, "Calibration done:\r\n\tSENS_DEVIATION: %.4f\r\n\tOFFSET_CORR: %.2f\r\n", sens_dev, offset);
	adc_pt1000_set_resistance_calibration(offset, sens_dev, true);

	return 0;
}