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2d5827682d
Signed-off-by: Ravi Chandra Sadineni <ravisadineni@chromium.org> BRANCH=none BUG=chrome-os-partner:56206 TEST=make buildall -j Change-Id: I22ac65f33b27b8ce8ad0687971f47b82395aa781 Reviewed-on: https://chromium-review.googlesource.com/370402 Commit-Ready: David Hendricks <dhendrix@chromium.org> Commit-Ready: Ravi Chandra Sadineni <ravisadineni@chromium.org> Tested-by: Ravi Chandra Sadineni <ravisadineni@chromium.org> Reviewed-by: David Hendricks <dhendrix@chromium.org>
59 lines
1.7 KiB
C
59 lines
1.7 KiB
C
/* Copyright 2015 The Chromium OS Authors. All rights reserved.
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* Use of this source code is governed by a BSD-style license that can be
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* found in the LICENSE file.
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*/
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/* Thermistor module for Chrome EC */
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#ifndef __CROS_EC_TEMP_SENSOR_THERMISTOR_H
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#define __CROS_EC_TEMP_SENSOR_THERMISTOR_H
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struct thermistor_data_pair {
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uint8_t mv; /* Scaled voltage level at ADC (in mV) */
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uint8_t temp; /* Temperature in Celsius */
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};
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struct thermistor_info {
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uint8_t scaling_factor; /* Scaling factor for voltage in data pair. */
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uint8_t num_pairs; /* Number of data pairs. */
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/*
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* Values between given data pairs will be calculated as points on
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* a line. Pairs can be derived using the Steinhart-Hart equation.
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*
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* Guidelines for data sets:
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* - Must contain at least two pairs.
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* - First and last pairs are the max and min.
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* - Pairs must be sorted in descending order.
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* - 5 pairs should provide reasonable accuracy in most cases. Use
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* points where the slope changes significantly or to recalibrate
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* the algorithm if needed.
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*/
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const struct thermistor_data_pair *data;
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};
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/**
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* @brief Calculate temperature using linear interpolation of data points.
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*
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* Given a set of datapoints, the algorithm will calculate the "step" in
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* between each one in order to interpolate missing entries.
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*
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* @param mv Value read from ADC (in millivolts).
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* @param info Reference data set and info.
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*
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* @return temperature in C
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*/
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int thermistor_linear_interpolate(uint16_t mv,
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const struct thermistor_info *info);
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/**
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* ncp15wb temperature conversion routine.
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*
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* @param adc 10bit raw data on adc.
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*
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* @return temperature in C.
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*/
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int ncp15wb_calculate_temp(uint16_t adc);
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#endif /* __CROS_EC_TEMP_SENSOR_THERMISTOR_NCP15WB_H */
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