Add a 12/24 hour setting to the clock

libraries/RTC/examples/AlarmClock/AlarmClock.pde

@@ -24,6 +24,7 @@
 #include <FreetronicsLCD.h>
 #include <Form.h>
 #include <Field.h>
+#include <BoolField.h>
 #include <SoftI2C.h>
 #include <DS1307RTC.h>
 #include <Melody.h>
@@ -39,6 +40,9 @@
 // Value to adjust for the voltage drop on D2.
 #define VOLTAGE_DROP_ADJUST     70  // 0.7 volts
 
+// Offsets of settings in the realtime clock's NVRAM.
+#define SETTING_24HOUR          0   // 0: 12 hour, 1: 24 hour
+
 // Initialize the LCD
 FreetronicsLCD lcd;
 
@@ -56,6 +60,7 @@ uint8_t prevHour = 24;
 // Create the main form and its fields.
 Form mainForm(lcd);
 FrontScreenField frontScreen(mainForm);
+BoolField hourMode(mainForm, "Hour display", "24 hour clock", "12 hour clock", false);
 
 void setup() {
     // Enable the screen saver.
@@ -67,6 +72,10 @@ void setup() {
     alarmMelody.setLoopDuration(120000UL);
     //alarmMelody.play();
 
+    // Read the clock settings from the realtime clock's NVRAM.
+    hourMode.setValue(rtc.readByte(SETTING_24HOUR) != 0);
+    frontScreen.set24HourMode(hourMode.value());
+
     // Show the main form for the first time.
     mainForm.show();
 }
@@ -97,6 +106,10 @@ void loop() {
     // Dispatch button events to the main form.
     int event = lcd.getButton();
     if (mainForm.dispatch(event) == FORM_CHANGED) {
+        if (hourMode.isCurrent()) {
+            frontScreen.set24HourMode(hourMode.value());
+            rtc.writeByte(SETTING_24HOUR, (byte)hourMode.value());
+        }
         prevHour = 24;      // Force an update of the main screen.
     }
 

libraries/RTC/examples/AlarmClock/FrontScreen.cpp

@@ -39,6 +39,7 @@ FrontScreenField::FrontScreenField(Form &form)
     , _voltageTrunc(36)
     , _batteryBars(IND_BATTERY_FULL)
     , _alarmActive(false)
+    , _hourMode(false)
 {
     _date.day = 1;
     _date.month = 1;
@@ -123,6 +124,15 @@ void FrontScreenField::setAlarmActive(bool active)
     }
 }
 
+void FrontScreenField::set24HourMode(bool value)
+{
+    if (_hourMode != value) {
+        _hourMode = value;
+        if (isCurrent())
+            updateTime();
+    }
+}
+
 void FrontScreenField::updateDate()
 {
     lcd()->setCursor(0, 0);
@@ -141,7 +151,11 @@ void FrontScreenField::updateTime()
 {
     lcd()->setCursor(0, 1);
     bool pm;
-    if (_time.hour == 0 || _time.hour == 12) {
+    if (_hourMode) {
+        lcd()->write('0' + _time.hour / 10);
+        lcd()->write('0' + _time.hour % 10);
+        pm = false;
+    } else if (_time.hour == 0 || _time.hour == 12) {
         lcd()->write('1');
         lcd()->write('2');
         pm = (_time.hour == 12);
@@ -161,7 +175,8 @@ void FrontScreenField::updateTime()
     lcd()->write(':');
     lcd()->write('0' + _time.second / 10);
     lcd()->write('0' + _time.second % 10);
-    lcd()->print(pm ? "pm" : "am");
+    if (!_hourMode)
+        lcd()->print(pm ? "pm" : "am");
 }
 
 void FrontScreenField::updateVoltage()

libraries/RTC/examples/AlarmClock/FrontScreen.h

@@ -46,6 +46,9 @@ public:
     bool isAlarmActive() const { return _alarmActive; }
     void setAlarmActive(bool active);
 
+    bool is24HourMode() const { return _hourMode; }
+    void set24HourMode(bool value);
+
 private:
     RTCDate _date;
     RTCTime _time;
@@ -53,6 +56,7 @@ private:
     int _voltageTrunc;
     int _batteryBars;
     bool _alarmActive;
+    bool _hourMode;
 
     void updateDate();
     void updateTime();