119 lines
4.8 KiB
C
119 lines
4.8 KiB
C
/*
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* MIT License
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*
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* Copyright (c) 2022 Joey Castillo
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in all
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* copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*/
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#include "thermistor_driver.h"
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#include "sam.h"
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#include "watch.h"
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#include "watch_utility.h"
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// assume we have no thermistor until thermistor_driver_init is called.
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static bool has_thermistor = false;
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bool thermistor_driver_init(void) {
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// once called, assume we have a thermistor unless proven otherwise
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has_thermistor = true;
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uint16_t value;
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#if THERMISTOR_ENABLE_VALUE == false
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const uint16_t threshold_value = 60000;
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#else
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const uint16_t threshold_value = 5000;
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#endif
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watch_enable_adc();
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// Enable analog circuitry on the sense pin, which is tied to the thermistor resistor divider.
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HAL_GPIO_TEMPSENSE_in();
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HAL_GPIO_TEMPSENSE_pmuxen(HAL_GPIO_PMUX_ADC);
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// Enable digital output on the enable pin, which is the power to the thermistor circuit.
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HAL_GPIO_TS_ENABLE_out();
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// and make sure it's DISABLED.
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HAL_GPIO_TS_ENABLE_write(!THERMISTOR_ENABLE_VALUE);
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// If the temperature sensor is connected, pulling the TS_ENABLE line to its disabled value
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// connects both sides of the voltage divider to the same potential. If enable value is false,
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// this will be high, if enable value is true it will be low, and TEMPSENSE should read the same.
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value = watch_get_analog_pin_level(HAL_GPIO_TEMPSENSE_pin());
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// If setting TS_ENABLE has no effect, there is no thermistor circuit connected to TEMPSENSE.
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if (value < threshold_value) has_thermistor = false;
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// now flip it to enable the temperature sensor
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HAL_GPIO_TS_ENABLE_write(THERMISTOR_ENABLE_VALUE);
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// If the temperature sensor is connected, pulling the TS_ENABLE line to its ENABLED value
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// means we should get a reasonable temperature at this point.
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value = watch_get_analog_pin_level(HAL_GPIO_TEMPSENSE_pin());
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// value should be >15000 and <55000 and (between -4° and 76° C)
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if (value < 15000 || value > 55000) has_thermistor = false;
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// clean up, disable everything we enabled earlier.
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watch_disable_adc();
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HAL_GPIO_TEMPSENSE_off();
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HAL_GPIO_TEMPSENSE_pmuxdis();
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HAL_GPIO_TS_ENABLE_write(!THERMISTOR_ENABLE_VALUE);
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HAL_GPIO_TS_ENABLE_off();
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return has_thermistor;
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}
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void thermistor_driver_enable(void) {
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if (!has_thermistor) return;
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// Enable the ADC peripheral, which we'll use to read the thermistor value.
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watch_enable_adc();
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// Enable analog circuitry on the sense pin, which is tied to the thermistor resistor divider.
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HAL_GPIO_TEMPSENSE_in();
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HAL_GPIO_TEMPSENSE_pmuxen(HAL_GPIO_PMUX_ADC);
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// Enable digital output on the enable pin, which is the power to the thermistor circuit.
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HAL_GPIO_TS_ENABLE_out();
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// and make sure it's off.
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HAL_GPIO_TS_ENABLE_write(!THERMISTOR_ENABLE_VALUE);
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}
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void thermistor_driver_disable(void) {
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if (!has_thermistor) return;
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// Disable the ADC peripheral.
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watch_disable_adc();
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// Disable analog circuitry on the sense pin to save power.
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HAL_GPIO_TEMPSENSE_pmuxdis();
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HAL_GPIO_TEMPSENSE_off();
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// Disable the enable pin's output circuitry.
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HAL_GPIO_TS_ENABLE_off();
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}
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float thermistor_driver_get_temperature(void) {
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if (!has_thermistor) return (float) 0xFFFFFFFF;
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// set the enable pin to the level that powers the thermistor circuit.
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HAL_GPIO_TS_ENABLE_write(THERMISTOR_ENABLE_VALUE);
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// get the sense pin level
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uint16_t value = watch_get_analog_pin_level(HAL_GPIO_TEMPSENSE_pin());
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// and then set the enable pin to the opposite value to power down the thermistor circuit.
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HAL_GPIO_TS_ENABLE_write(!THERMISTOR_ENABLE_VALUE);
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return watch_utility_thermistor_temperature(value, THERMISTOR_HIGH_SIDE, THERMISTOR_B_COEFFICIENT, THERMISTOR_NOMINAL_TEMPERATURE, THERMISTOR_NOMINAL_RESISTANCE, THERMISTOR_SERIES_RESISTANCE);
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}
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