Fix missing documentation for many clock faces:

* Move from .c to .h as needed for consistency.
* When missing from both, copy from pull request or wiki.
* When missing entirely, infer functionality from source code.

movement/watch_faces/sensor/accelerometer_data_acquisition_face.h

@@ -25,6 +25,12 @@
 #ifndef ACCELEROMETER_DATA_ACQUISITION_FACE_H_
 #define ACCELEROMETER_DATA_ACQUISITION_FACE_H_
 
+/*
+ * ACCELEROMETER DATA ACQUISITION
+ *
+ * TODO: Add description here, including controls.
+ */
+
 #include "movement.h"
 
 #define ACCELEROMETER_DATA_ACQUISITION_INVALID ((uint64_t)(0b11))   // all bits are 1 when the flash is erased

movement/watch_faces/sensor/lightmeter_face.c

@@ -22,37 +22,6 @@
  * SOFTWARE.
  */
 
-/* Aperture-priority Light Meter Face
- *
- * Tested with the "Q3Q-SWAB-A1-00 Temperature + Test Points + OPT3001" flexboard.
- * This flexboard could use a revision: 
- *
- *  - The thermistor components should be moved west a mm or flipped to the backside
- *    to avoid stressing the flexboard against the processor so much.
- *  - The 'no connect' pad falls off easily.
- *
- * Controls:
- *
- *  - Trigger a measurement by long-pressing Alarm.
- *    Sensor integration is happening when the Signal indicator is on.
- *
- *  - ISO setting can be cycled by long-pressing Light.
- *    During integration the current ISO setting will be displayed. 
- *
- *  - EV measurement in the top right: "LAP" indicates "half stop". 
- *    So "LAP -1" means EV = -1.5. Likewise "LAP 13" means EV = +13.5  
- *
- *  - Aperture in the bottom right: the last 3 main digits are the f-stop. 
- *    Adjust this number in half-stop increments using Alarm = +1/2 and Light = -1/2. 
- *
- *  - Best shutter speed in the bottom left: the first 3 digits are the shutter speed. 
- *    Some special chars are needed here: "-" = seconds, "h" = extra half second, "K" = thousands.
- *    "HI" or "LO" if there's no shutter in the dictionary within 0.5 stops of correct exposure.
- *
- *  - Mode long-press changes the main digits to show raw sensor lux measurements.
- *
- */
-
 #include <stdlib.h>
 #include <string.h>
 #include <math.h>

movement/watch_faces/sensor/lightmeter_face.h

@@ -25,6 +25,37 @@
 #ifndef LIGHTMETER_FACE_H_
 #define LIGHTMETER_FACE_H_
 
+/*
+ * Aperture-priority Light Meter Face
+ *
+ * Tested with the "Q3Q-SWAB-A1-00 Temperature + Test Points + OPT3001" flexboard.
+ * This flexboard could use a revision: 
+ *
+ *  - The thermistor components should be moved west a mm or flipped to the backside
+ *    to avoid stressing the flexboard against the processor so much.
+ *  - The 'no connect' pad falls off easily.
+ *
+ * Controls:
+ *
+ *  - Trigger a measurement by long-pressing Alarm.
+ *    Sensor integration is happening when the Signal indicator is on.
+ *
+ *  - ISO setting can be cycled by long-pressing Light.
+ *    During integration the current ISO setting will be displayed. 
+ *
+ *  - EV measurement in the top right: "LAP" indicates "half stop". 
+ *    So "LAP -1" means EV = -1.5. Likewise "LAP 13" means EV = +13.5  
+ *
+ *  - Aperture in the bottom right: the last 3 main digits are the f-stop. 
+ *    Adjust this number in half-stop increments using Alarm = +1/2 and Light = -1/2. 
+ *
+ *  - Best shutter speed in the bottom left: the first 3 digits are the shutter speed. 
+ *    Some special chars are needed here: "-" = seconds, "h" = extra half second, "K" = thousands.
+ *    "HI" or "LO" if there's no shutter in the dictionary within 0.5 stops of correct exposure.
+ *
+ *  - Mode long-press changes the main digits to show raw sensor lux measurements.
+ */
+
 #include "movement.h"
 #include "opt3001.h"
 

movement/watch_faces/sensor/thermistor_logging_face.h

@@ -25,6 +25,34 @@
 #ifndef THERMISTOR_LOGGING_FACE_H_
 #define THERMISTOR_LOGGING_FACE_H_
 
+/*
+ * THERMISTOR LOGGING (aka Temperature Log)
+ *
+ * This watch face automatically logs the temperature once an hour, and
+ * maintains a 36-hour log of readings. This watch face is admittedly rather
+ * complex, and bears some explanation.
+ *
+ * The main display shows the letters “TL” in the top left, indicating the
+ * name of the watch face. At the top right, it displays the index of the
+ * reading; 0 represents the most recent reading taken, 1 represents one
+ * hour earlier, etc. The bottom line in this mode displays the logged
+ * temperature.
+ *
+ * A short press of the “Alarm” button advances to the next oldest reading;
+ * you will see the number at the top right advance from 0 to 1 to 2, all
+ * the way to 35, the oldest reading available.
+ *
+ * A short press of the “Light” button will briefly display the timestamp
+ * of the reading. The letters at the top left will display the word “At”,
+ * and the main line will display the timestamp of the currently displayed
+ * data point. The number in the top right will display the day of the month
+ * for the given data point; for example, you can read “At 22 3:00 PM” as
+ * ”At 3:00 PM on the 22nd”.
+ *
+ * If you need to illuminate the LED to read the data point, long press the
+ * Light button and release it.
+ */
+
 #include "movement.h"
 #include "watch.h"
 

movement/watch_faces/sensor/thermistor_readout_face.h

@@ -25,6 +25,29 @@
 #ifndef THERMISTOR_READOUT_FACE_H_
 #define THERMISTOR_READOUT_FACE_H_
 
+/*
+ * THERMISTOR READOUT (aka Temperature Display)
+ *
+ * This watch face is designed to work with either the Temperature + GPIO
+ * sensor board or the Temperature + Light sensor board. It reads the current
+ * temperature from the thermistor voltage divider on the sensor board, and
+ * displays the current temperature in degrees Celsius.
+ *
+ * When the watch is on your wrist, your body heat interferes with an ambient
+ * temperature reading, but if you set it on a bedside table, strap it to your
+ * bike handlebars or place it outside of your tent while camping, this watch
+ * face can act as a digital thermometer for displaying ambient conditions.
+ *
+ * The temperature sensor watch face automatically samples the temperature
+ * once every five seconds, and it illuminates the Signal indicator just
+ * before taking a reading.
+ *
+ * Pressing the ALARM button toggles the unit display from Celsius to
+ * Fahrenheit. Technically this sets the global “Metric / Imperial” flag, so
+ * any other watch face that displays localizable units will display them in
+ * the system selected here.
+ */
+
 #include "movement.h"
 
 void thermistor_readout_face_setup(movement_settings_t *settings, uint8_t watch_face_index, void ** context_ptr);

movement/watch_faces/sensor/thermistor_testing_face.c

@@ -28,11 +28,6 @@
 #include "thermistor_driver.h"
 #include "watch.h"
 
-// This watch face is designed for testing temperature sensor boards.
-// It displays temperature readings at a relatively fast rate of 8 Hz,
-// and disables low energy mode so my testing device doesn't sleep.
-// You more than likely want to use thermistor_readout_face instead.
-
 static void _thermistor_testing_face_update_display(bool in_fahrenheit) {
     thermistor_driver_enable();
     float temperature_c = thermistor_driver_get_temperature();

movement/watch_faces/sensor/thermistor_testing_face.h

@@ -25,6 +25,17 @@
 #ifndef THERMISTOR_TESTING_FACE_H_
 #define THERMISTOR_TESTING_FACE_H_
 
+/*
+ * THERMISTOR TESTING FACE
+ *
+ * This watch face is designed for testing temperature sensor boards.
+ * It displays temperature readings at a relatively fast rate of 8 Hz,
+ * and disables low energy mode so my testing device doesn't sleep.
+ * You more than likely want to use thermistor_readout_face instead.
+ *
+ * Press ALARM to toggle display of metric vs. imperial units.
+ */
+
 #include "movement.h"
 
 void thermistor_testing_face_setup(movement_settings_t *settings, uint8_t watch_face_index, void ** context_ptr);