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/demo/character_set_face.h

@@ -25,6 +25,17 @@
 #ifndef CHARACTER_SET_FACE_H_
 #define CHARACTER_SET_FACE_H_
 
+/*
+ * CHARACTER SET FACE
+ *
+ * This watch face displays all of the characters in the Sensor Watch character
+ * set. You can advance from one character to the next with a short press of the
+ * ALARM button.
+ *
+ * This watch face may be useful to watch face developers, in that it can help
+ * them to understand which characters will work in different positions.
+ */
+
 #include "movement.h"
 
 void character_set_face_setup(movement_settings_t *settings, uint8_t watch_face_index, void ** context_ptr);

movement/watch_faces/demo/chirpy_demo_face.h

@@ -25,8 +25,6 @@
 #ifndef CHIRPY_DEMO_FACE_H_
 #define CHIRPY_DEMO_FACE_H_
 
-#include "movement.h"
-
 /*
  * CHIRPY DEMO FACE
  * 
@@ -50,9 +48,10 @@
  * 
  * To record and decode a chirpy transmission on your computer, you can use the web app here:
  * https://jealousmarkup.xyz/off/chirpy/rx/
- * 
  */
 
+#include "movement.h"
+
 void chirpy_demo_face_setup(movement_settings_t *settings, uint8_t watch_face_index, void ** context_ptr);
 void chirpy_demo_face_activate(movement_settings_t *settings, void *context);
 bool chirpy_demo_face_loop(movement_event_t event, movement_settings_t *settings, void *context);

movement/watch_faces/demo/demo_face.h

@@ -25,6 +25,17 @@
 #ifndef DEMO_FACE_H_
 #define DEMO_FACE_H_
 
+/*
+ * DEMO FACE
+ *
+ * This watch was designed for the Crowd Supply marketing team, so they could
+ * photograph the various functions of Sensor Watch. The Alarm button advances
+ * through static screens that simulate different watch faces.
+ *
+ * This watch face may only be useful to you if you need to photograph Sensor
+ * Watch, i.e. for a blog post.
+ */
+
 #include "movement.h"
 
 void demo_face_setup(movement_settings_t *settings, uint8_t watch_face_index, void ** context_ptr);

movement/watch_faces/demo/frequency_correction_face.h

@@ -25,6 +25,18 @@
 #ifndef FREQUENCY_CORRECTION_FACE_H_
 #define FREQUENCY_CORRECTION_FACE_H_
 
+/*
+ * FREQUENCY CORRECTION FACE
+ *
+ * While active, this face generates a square-wave on pin A1 of the 9-pin
+ * connector. The output frequency is adjustable from 64 Hz to 0.5 Hz.
+ * Long-press ALARM to cycle through available frequencies.
+ *
+ * This face also displays the value of the watch's frequency-correction
+ * register. This setting varies from -127 to +127. Press LIGHT to increment
+ * or ALARM to decrement the setting.
+ */
+
 #include "movement.h"
 
 typedef struct {

movement/watch_faces/demo/hello_there_face.h

@@ -25,6 +25,13 @@
 #ifndef HELLO_THERE_FACE_H_
 #define HELLO_THERE_FACE_H_
 
+/*
+ * HELLO THERE FACE
+ *
+ * A simple demo that displays the word "Hello" and then the word "there",
+ * on an endless loop. Press ALARM to pause or resume the animation.
+ */
+
 #include "movement.h"
 
 typedef struct {

movement/watch_faces/demo/lis2dw_logging_face.h

@@ -25,6 +25,14 @@
 #ifndef LIS2DW_LOGGING_FACE_H_
 #define LIS2DW_LOGGING_FACE_H_
 
+/*
+ * LIS2DW Accelerometer Data Logger
+ *
+ * This is an experimental watch face for logging data on the “Sensor Watch
+ * Motion Express” board. I will add more documentation for this watch face
+ * once this sensor board is more widely available.
+ */
+
 #include "movement.h"
 #include "watch.h"
 

movement/watch_faces/demo/voltage_face.h

@@ -25,6 +25,17 @@
 #ifndef VOLTAGE_FACE_H_
 #define VOLTAGE_FACE_H_
 
+/*
+ * VOLTAGE face
+ *
+ * This watch face is very simple and has no controls to speak of. It displays
+ * the battery voltage as measured by the SAM L22’s ADC.
+ *
+ * Note that the Simple Clock watch face includes a low battery warning, so you
+ * don’t technically need to this watch face unless you want to track the
+ * battery level.
+ */
+
 #include "movement.h"
 
 void voltage_face_setup(movement_settings_t *settings, uint8_t watch_face_index, void ** context_ptr);