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Add conversion function for resistance to temperature conversion and add it to thept command of the shell

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Mario Hüttel
2020-02-15 20:31:38 +01:00
parent 92526e71b2
commit 7df97831be
4 changed files with 127 additions and 1 deletions
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stm-firmware/temp-converter.c Normal file
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/* 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 GDSII-Converter. If not, see <http://www.gnu.org/licenses/>.
*/
#include <reflow-controller/temp-converter.h>
#include <reflow-controller/temp-converter-data.h>
#include <helper-macros/helper-macros.h>
static const float temp_lookup[(TEMP_CONVERSION_MAX_RES-TEMP_CONVERSION_MIN_RES) / TEMP_CONVERSION_RES_STEP+1] = {TEMP_CONVERSION_ARRAY_DATA};
int temp_converter_convert_resistance_to_temp(float resistance, float *temp_out)
{
int ret_val;
unsigned int i;
unsigned int lower_idx = COUNT_OF(temp_lookup) - 1;
float diff_to_low_resistance;
float diff_high_low;
float low;
/* Check pointer */
if (!temp_out)
return -1000;
if (resistance < TEMP_CONVERSION_MIN_RES) {
*temp_out = temp_lookup[0];
ret_val = -1;
goto return_ret_val;
} else if (resistance > TEMP_CONVERSION_MAX_RES) {
*temp_out = temp_lookup[COUNT_OF(temp_lookup)-1];
ret_val = 1;
goto return_ret_val;
}
/* Resistance is in range */
ret_val = 0;
/* Calculate lower index for given reistance */
for (i = 1; i < COUNT_OF(temp_lookup); i++) {
if (resistance <= TEMP_CONVERSION_MIN_RES + TEMP_CONVERSION_RES_STEP * i) {
lower_idx = i - 1;
break;
}
}
/* Get the lower temperature limit of the current range */
low = temp_lookup[lower_idx];
/* Difference to higher limit */
diff_high_low = temp_lookup[lower_idx+1] - low;
/* Resistance difference to lower limit's resistance value */
diff_to_low_resistance = resistance - (float)(TEMP_CONVERSION_MIN_RES + TEMP_CONVERSION_RES_STEP * lower_idx);
/* Calculate output temperature */
*temp_out = (diff_to_low_resistance / TEMP_CONVERSION_RES_STEP) * diff_high_low + low;
return_ret_val:
return ret_val;
}