movement: add voltage monitor watch face

movement/watch_faces/demos/voltage_face.c

@@ -0,0 +1,66 @@
+#include <stdlib.h>
+#include <string.h>
+#include "voltage_face.h"
+#include "watch.h"
+
+void _voltage_face_update_display() {
+    char buf[14];
+    float voltage = (float)watch_get_vcc_voltage() / 1000.0;
+    sprintf(buf, "BA  %4.2f V", voltage);
+    // printf("%s\n", buf);
+    watch_display_string(buf, 0);
+}
+
+void voltage_face_setup(movement_settings_t *settings, void ** context_ptr) {
+    (void) settings;
+    (void) context_ptr;
+}
+
+void voltage_face_activate(movement_settings_t *settings, void *context) {
+    (void) settings;
+    (void) context;
+    watch_enable_adc();
+    // if we set the reference voltage here, watch_get_vcc_voltage won't do it over and over
+    watch_set_analog_reference_voltage(ADC_REFERENCE_INTREF);
+}
+
+bool voltage_face_loop(movement_event_t event, movement_settings_t *settings, void *context) {
+    (void) settings;
+    (void) context;
+    watch_date_time date_time;
+    switch (event.event_type) {
+        case EVENT_MODE_BUTTON_UP:
+            movement_move_to_next_face();
+            break;
+        case EVENT_LIGHT_BUTTON_DOWN:
+            movement_illuminate_led();
+            break;
+        case EVENT_ACTIVATE:
+            _voltage_face_update_display();
+            break;
+        case EVENT_TICK:
+            date_time = watch_rtc_get_date_time();
+            if (date_time.unit.second % 5 == 4) {
+                watch_set_indicator(WATCH_INDICATOR_SIGNAL);
+            } else if (date_time.unit.second % 5 == 0) {
+                _voltage_face_update_display();
+                watch_clear_indicator(WATCH_INDICATOR_SIGNAL);
+            }
+            break;
+        case EVENT_TIMEOUT:
+            movement_move_to_face(0);
+            break;
+        default:
+            break;
+    }
+
+    return true;
+}
+
+void voltage_face_resign(movement_settings_t *settings, void *context) {
+    (void) settings;
+    (void) context;
+    // make sure to restore the default in the end.
+    watch_set_analog_reference_voltage(ADC_REFCTRL_REFSEL_INTVCC2_Val);
+    watch_disable_adc();
+}

movement/watch_faces/demos/voltage_face.h

@@ -0,0 +1,19 @@
+#ifndef VOLTAGE_FACE_H_
+#define VOLTAGE_FACE_H_
+
+#include "movement.h"
+
+void voltage_face_setup(movement_settings_t *settings, void ** context_ptr);
+void voltage_face_activate(movement_settings_t *settings, void *context);
+bool voltage_face_loop(movement_event_t event, movement_settings_t *settings, void *context);
+void voltage_face_resign(movement_settings_t *settings, void *context);
+
+static const watch_face_t voltage_face = {
+    voltage_face_setup,
+    voltage_face_activate,
+    voltage_face_loop,
+    voltage_face_resign,
+    NULL
+};
+
+#endif // VOLTAGE_FACE_H_