1 files changed, 58 insertions, 0 deletions
diff --git a/watch-library/shared/driver/thermistor_driver.c b/watch-library/shared/driver/thermistor_driver.c
new file mode 100644
index 00000000..73bdef41
--- /dev/null
+++ b/watch-library/shared/driver/thermistor_driver.c
@@ -0,0 +1,58 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2022 Joey Castillo
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#include "thermistor_driver.h"
+#include "watch.h"
+#include "watch_utility.h"
+
+void thermistor_driver_enable(void) {
+    // Enable the ADC peripheral, which we'll use to read the thermistor value.
+    watch_enable_adc();
+    // Enable analog circuitry on the sense pin, which is tied to the thermistor resistor divider.
+    watch_enable_analog_input(THERMISTOR_SENSE_PIN);
+    // Enable digital output on the enable pin, which is the power to the thermistor circuit.
+    watch_enable_digital_output(THERMISTOR_ENABLE_PIN);
+    // and make sure it's off.
+    watch_set_pin_level(THERMISTOR_ENABLE_PIN, !THERMISTOR_ENABLE_VALUE);
+}
+
+void thermistor_driver_disable(void) {
+    // Disable the ADC peripheral.
+    watch_disable_adc();
+    // Disable analog circuitry on the sense pin to save power.
+    watch_disable_analog_input(THERMISTOR_SENSE_PIN);
+    // Disable the enable pin's output circuitry.
+    watch_disable_digital_output(THERMISTOR_ENABLE_PIN);
+}
+
+float thermistor_driver_get_temperature(void) {
+    // set the enable pin to the level that powers the thermistor circuit.
+    watch_set_pin_level(THERMISTOR_ENABLE_PIN, THERMISTOR_ENABLE_VALUE);
+    // get the sense pin level
+    uint16_t value = watch_get_analog_pin_level(THERMISTOR_SENSE_PIN);
+    // and then set the enable pin to the opposite value to power down the thermistor circuit.
+    watch_set_pin_level(THERMISTOR_ENABLE_PIN, !THERMISTOR_ENABLE_VALUE);
+
+    return watch_utility_thermistor_temperature(value, THERMISTOR_HIGH_SIDE, THERMISTOR_B_COEFFICIENT, THERMISTOR_NOMINAL_TEMPERATURE, THERMISTOR_NOMINAL_RESISTANCE, THERMISTOR_SERIES_RESISTANCE);
+}