B4R Tutorial Digital Clock and Alarm without using a RTC

A digital clock and alarm without making use of a RTC. It uses:
Uno R3
LCD 1602 (to display the clock and the alarm)
Piezo Buzzer (to sound the preset alarm)
10K Pot (adjust the contrast of the LCD display)
220 Ohm resistor (make it bigger to dim the backlight intensity more)
4 x buttons (from left to right in the below image - increment value, decrement value, edit mode, alarm on/off)
Numerous wires

It uses libraries:
rCore
rLiquidCrystal

The bell custom character is created and displayed via inline C code

Wiring diagram:

Edit Alarm Minutes - alarm is active

Clock running and alarm set, and alarm activated (bell showing)

Clock running, alarm set, but alarm not activated (bell not showing)

Press the edit mode button (3rd from left) to edit hours, minutes, and seconds of the time or of the alarm (every edit/mode button press will take you to the next value to be adjusted)
Use the increment (first from left) and decrement (second from left) buttons to adjust/set hours, minutes, seconds of the time and the alarm when edit mode has been activated.
Use the right most button to activate/deactivate the alarm. This button will also silence the alarm when the alarm is ringing.

Sample Code:

#Region Project Attributes
    #AutoFlushLogs: True
    #StackBufferSize: 300
#End Region

Sub Process_Globals
    Public Serial1 As Serial
    Private hours, minutes, seconds As Int = 0
    Dim alarmhours, alarmminutes, alarmseconds As Int = 0
    Private timer1 As Timer
    Private lcd As LiquidCrystal
    Dim pa0, pa1, pa2, pa3, buzzerpin As Pin
    Dim hour_changed, minute_changed, second_changed As Boolean = False
    Dim alarmhour_changed, alarmminute_changed, alarmsecond_changed As Boolean = False
    Dim mode_changed As Boolean = False
    Dim mode As Int = 0
    Dim alarm_active As Boolean = False
 
End Sub

Private Sub AppStart
    Serial1.Initialize(115200)
    Log("AppStart")
    timer1.Initialize("Timer1_Tick", 1000)
 
    pa0.Initialize(pa0.A0, pa0.MODE_INPUT_PULLUP)           'increment time depending on edit mode
    pa1.Initialize(pa1.A1, pa1.MODE_INPUT_PULLUP)           'select edit mode
    pa2.Initialize(pa2.A2, pa1.MODE_INPUT_PULLUP)           'decrement time depending on edit mode
    pa3.Initialize(pa3.A3, pa3.MODE_INPUT_PULLUP)
    buzzerpin.Initialize(3, buzzerpin.MODE_OUTPUT)
    buzzerpin.DigitalWrite(False)
 
    pa0.AddListener("pa0_StateChanged")
    pa1.AddListener("pa1_StateChanged")
    pa2.AddListener("pa2_StateChanged")
    pa3.AddListener("pa3_StateChanged")
 
    lcd.Initialize(8, 255, 9, Array As Byte (4, 5, 6, 7))
    lcd.Begin(16, 2)
    lcd.Blink = False
    timer1.Enabled = True
 
    'set time and alarm initial values
    hours = 16
    minutes = 48
    seconds = 0
    alarmhours = 07
    alarmminutes = 15
    alarmseconds = 0
 
    lcd.SetCursor(9,0)
    lcd.Write("Time")
    lcd.SetCursor(9,1)
    lcd.Write("Alarm")
    RunNative("createCharsAlarm", Null)        'create an alarm / bell character

End Sub

Sub pa3_StateChanged

    Delay(20)
 
    If mode = 0 Then
        If alarm_active = False Then
            If pa3.DigitalRead = True Then
                alarm_active = True
                lcd.SetCursor(15,1)
                RunNative("writeCharAlarm", 0)   'display the Bell special character
            End If
        Else
            If pa3.DigitalRead = True Then
                alarm_active = False
                buzzerpin.DigitalWrite(False)
                lcd.SetCursor(15,1)
                lcd.Write(" ")
            End If
        End If
    End If
  
End Sub

Sub pa0_StateChanged
    Delay(20)
 
    If mode = 1 Then                             'edit mode 1 - set the hours of the time
        If Not(hour_changed) Then
            hours = hours + 1
            If hours = 24 Then hours = 0
            lcd.Write(NumberFormat(hours, 2, 0))
            lcd.SetCursor(0,0)
            hour_changed = Not(hour_changed)
        Else
            hour_changed = Not(hour_changed)
        End If
    End If
 
    If mode = 2 Then
        If Not(minute_changed) Then
            minutes = minutes + 1
            If minutes = 60 Then minutes = 0
            lcd.Write(NumberFormat(minutes, 2, 0))
            lcd.SetCursor(3,0)
            minute_changed = Not(minute_changed)
        Else
            minute_changed = Not(minute_changed)
        End If
    End If
 
    If mode = 3 Then
        If Not(second_changed) Then
            seconds = seconds + 1
            If seconds = 60 Then seconds = 0
            lcd.Write(NumberFormat(seconds, 2, 0))
            lcd.SetCursor(6,0)
            second_changed = Not(second_changed)
        Else
            second_changed = Not(second_changed)
        End If
    End If
 
 
    If mode = 4 Then
        If Not(alarmhour_changed) Then
            alarmhours = alarmhours + 1
            If alarmhours = 24 Then alarmhours = 0
            lcd.Write(NumberFormat(alarmhours, 2, 0))
            lcd.SetCursor(0,1)
            alarmhour_changed = Not(alarmhour_changed)
        Else
            alarmhour_changed = Not(alarmhour_changed)
        End If
    End If
 
    If mode = 5 Then
        If Not(alarmminute_changed) Then
            alarmminutes = alarmminutes + 1
            If alarmminutes = 60 Then alarmminutes = 0
            lcd.Write(NumberFormat(alarmminutes, 2, 0))
            lcd.SetCursor(3,1)
            alarmminute_changed = Not(alarmminute_changed)
        Else
            alarmminute_changed = Not(alarmminute_changed)
        End If
    End If
 
    If mode = 6 Then
        If Not(alarmsecond_changed) Then
            alarmseconds = alarmseconds + 1
            If alarmseconds = 60 Then alarmseconds = 0
            lcd.Write(NumberFormat(alarmseconds, 2, 0))
            lcd.SetCursor(6,1)
            alarmsecond_changed = Not(alarmsecond_changed)
        Else
            alarmsecond_changed = Not(alarmsecond_changed)
        End If
    End If
 
 
End Sub

Sub pa2_StateChanged
    Delay(20)
 
    If mode = 1 Then                       
        If Not(hour_changed) Then
            hours = hours - 1
            If hours = -1 Then hours = 23
            lcd.Write(NumberFormat(hours, 2, 0))
            lcd.SetCursor(0,0)
            hour_changed = Not(hour_changed)
        Else
            hour_changed = Not(hour_changed)
        End If
    End If
 
    If mode = 2 Then
        If Not(minute_changed) Then
            minutes = minutes - 1
            If minutes = -1 Then minutes = 59
            lcd.Write(NumberFormat(minutes, 2, 0))
            lcd.SetCursor(3,0)
            minute_changed = Not(minute_changed)
        Else
            minute_changed = Not(minute_changed)
        End If
    End If
 
    If mode = 3 Then
        If Not(second_changed) Then
            seconds = seconds - 1
            If seconds = -1 Then seconds = 59
            lcd.Write(NumberFormat(seconds, 2, 0))
            lcd.SetCursor(6,0)
            second_changed = Not(second_changed)
        Else
            second_changed = Not(second_changed)
        End If
    End If
 
 
    If mode = 4 Then
        If Not(alarmhour_changed) Then
            alarmhours = alarmhours - 1
            If alarmhours = -1 Then alarmhours = 23
            lcd.Write(NumberFormat(alarmhours, 2, 0))
            lcd.SetCursor(0,1)
            alarmhour_changed = Not(alarmhour_changed)
        Else
            alarmhour_changed = Not(alarmhour_changed)
        End If
    End If
 
    If mode = 5 Then
        If Not(alarmminute_changed) Then
            alarmminutes = alarmminutes - 1
            If alarmminutes = -1 Then alarmminutes = 59
            lcd.Write(NumberFormat(alarmminutes, 2, 0))
            lcd.SetCursor(3,1)
            alarmminute_changed = Not(alarmminute_changed)
        Else
            alarmminute_changed = Not(alarmminute_changed)
        End If
    End If
 
    If mode = 6 Then
        If Not(alarmsecond_changed) Then
            alarmseconds = alarmseconds - 1
            If alarmseconds = -1 Then alarmseconds = 59
            lcd.Write(NumberFormat(alarmseconds, 2, 0))
            lcd.SetCursor(6,1)
            alarmsecond_changed = Not(alarmsecond_changed)
        Else
            alarmsecond_changed = Not(alarmsecond_changed)
        End If
    End If
 
 
End Sub

Sub pa1_StateChanged
    Delay(20)
 
    timer1.Enabled = False                            'disable the timer while we adjuts the time or alamr
    If Not(mode_changed) Then
        mode_changed = Not(mode_changed)
        mode = mode + 1                               'increase the mode (by default the mode = 0)
    Else
        mode_changed = Not(mode_changed)
    End If
 
    If mode = 1 Then                                  'mode to edit hours of time
        lcd.SetCursor(0,0)
        lcd.Blink = True
        lcd.CursorOn = True
    else if mode = 2 Then
        lcd.SetCursor(3,0)
        lcd.Blink = True
        lcd.CursorOn = True
    else if mode = 3 Then
        lcd.SetCursor(6,0)
        lcd.Blink = True
        lcd.CursorOn = True
    else if mode = 4 Then                            'mode to edit hours of alarm
        lcd.SetCursor(0,1)
        lcd.Blink = True
        lcd.CursorOn = True
    else if mode = 5 Then
        lcd.SetCursor(3,1)
        lcd.Blink = True
        lcd.CursorOn = True
    else if mode = 6 Then
        lcd.SetCursor(6,1)
        lcd.Blink = True
        lcd.CursorOn = True
    Else
        mode = 0
        lcd.Blink = False
        lcd.CursorOn = False
        timer1.Enabled = True
    End If
 
End Sub

Sub Timer1_Tick

    seconds = seconds + 1
 
    If seconds = 60 Then
        seconds = 0
        minutes = minutes + 1
    End If
 
    If minutes = 60 Then
        minutes = 0
        hours = hours + 1
    End If
    If hours = 24 Then
        hours = 0
    End If
 
    lcd.SetCursor(0,0)
    lcd.Write(NumberFormat(hours, 2, 0))
    lcd.Write(":")
    lcd.Write(NumberFormat(minutes, 2, 0))
    lcd.Write(":")
    lcd.Write(NumberFormat(seconds, 2, 0))
    lcd.SetCursor(0,1)
    lcd.Write(NumberFormat(alarmhours, 2, 0))
    lcd.Write(":")
    lcd.Write(NumberFormat(alarmminutes, 2, 0))
    lcd.Write(":")
    lcd.Write(NumberFormat(alarmseconds, 2, 0))
 
    ring_alarm
 
End Sub

Sub ring_alarm

    If alarm_active = True Then
        If alarmhours = hours And alarmminutes = minutes Then             'ring the alarm for 1 minute with alternate on/off pulses during a 2 seconds period (i.e 1 second on / 1 second off)
            If seconds Mod 2 = 0 Then
                buzzerpin.DigitalWrite(True)
            Else
                buzzerpin.DigitalWrite(False)
            End If
        Else
            buzzerpin.DigitalWrite(False)
        End If
    End If
 
End Sub

#if C                         

 //this creates the Bell character
    Byte alm[8] = {
    0b00100,
    0b01110,
    0b01110,
    0b01110,
    0b11111,
    0b00000,
    0b00100,
    0b00000
    };

    void createCharsAlarm(B4R::Object* o) {
       b4r_main::_lcd->lc->createChar(0, alm);
    }

    void writeCharAlarm(B4R::Object* o) {
       b4r_main::_lcd->lc->write((Byte)o->toULong());
    }

#end if