Retrograde Minute Hand Clock

[mkstevo]

Yes! Another clock! This one has a mechanical minute hand with a retrograde action. The hand moves from "zero" to the "sixty" minute position, once the minutes reach sixty, the hand rotates anticlockwise, back to zero and the hour indicated on the LED display progresses to the new hour.

The video shows the clock being powered up and moving to the current time. When first plugged in, the LED display shows the software build date ( 21 - 05 - 21 ), the minute hand rotates anticlockwise to zero minutes, the hand then rotates to the sixty minute position (this is to check that the limit switches are working) during this proceedure, the LED display shows a count of the steps needed to move the hand from one position to the other - if this is less than that required, an error would be displayed. The minute hand then returns back to zero. The clock module is initialised (the LED momentarily shows "IC") and assuming the time can be loaded, the current time (hours then minutes) is shown on the LED. The minute hand then moves to point to the current time, the LED shows the hours and timekeeping commences.

Inspired by the range of Reservoir Watches.

Code updated with "Error" changed to "ErrorSub" following Anobium's suggestion. When the PCBs arrived I found that the steps required needed a change or two to allow a full rotation, not unexpected really given the prototype was made with a sheet of cardboard with holes punched to mount the motor. This code has those minor tweaks made.

YouTube Video

#Option Explicit
'Pic 16F1829 Retrograde minute clock
'(c) MkEDS 2021

'This is to drive a 28YBJ-48 Stepper motor.
'The motor driver transistor bases are connected
'to MtrA, MtrB, MtrC and MtrD. The collectors of
'these transistors are connected to the A,B,C and D
'windings of the motor.

'The wires of the motor are:
'Red  5V
'Ora  A
'Yel  B
'Pnk  C
'Blu  D

'A serial two digit LED display is connected to show the hours.
'The stepper motor points to the minutes.

'A DS3231 clock module is connected to keep the time.

'The date is always set to the compile date as the date cannot be displayed.

'When powered on, the compile date is shown on the display.

'The stepper motor is then turned anticlockwise until the pointer makes contact
'with the start switch.

'The stepper motor is then turned clockwise until the pointer makes contact with
'the end switch.

'The stepper motor is then turned anticlockwise back to the start position.

'The start contacts should be positioned and aligned with the zero minute marker.
'The end contacts should be algned just past the sixty minute marker.

'If the stepper motor fails to rotate for the correct number of steps (more than
'2999 and less than 3500) the display will show "EH" and will halt to indicate
'an error with the hand.

'The DS3231 will be initialised with the display showing briefly "IC".
'If the DS3231 is not detected the display will show "EC" and will halt to indicate
'an error with the clock.

'If there are no errors, the hours will be shown with a decimal point on the first
'digit, followed by the minutes with a decimal point on the second digit.

'The display will then show the current hour and the pointer will move to indicate the
'current minutes.

'At 59 minutes and 55 seconds, the minute pointer will move anticlockwise back to
'zero minutes. This takes around 8 seconds, the hour will update to show the new
'hour.

'Hours are only ever displayed in 12 hour format with a leading zero.

'If the DS3231 has stalled due to a power failure, the two decimal points will alternate
'every second. This will indicate that the time needs checking. Setting the time will
'clear this.

'There are three buttons fitted, Up Down and OK.

'While not in setting mode, pressing the "Up" button will show the temperature
'on the display, with no decimal point. Pressing the "Down" button will show the
'minute with a decimal point on the second digit.

'To adjust the time:
'Press and hold the "Ok" button for a second.
'The clock will show the hour, with a decimal point on the first digit, pressing
'the up or down buttons will adjust the hour. Press and release the "Ok" button
'to store the hour and adjust the minute. The minute will be displayed with a
'decimal point on the second digit, pressing the up or down buttons will adjust
'the current minute. Press the "Ok" button to store the time. If the minutes
'have been altered, the seconds will be set to zero and timekeeping will start
'when the "Ok" button is finally pressed then released.

'The date cannot be shown and is reset to the compile date when ever the time is
'adjusted.

'Should the pointer be turned accidentally:
'If it is advanced, it will reach the end switch before sixty minutes, the pointer
'will return to zero minutes, then rotate to the correct time.

'If it is retarded, it will return to zero minutes at 59 minutes and 55 seconds
'then continue as normal.

#Chip 16F1829, 32
#Config CP=On
'Read protected

Set Not_WPUEN = 0 'Enable pullups in general.
Set WPUA0     = 0
Set WPUA1     = 0
Set WPUA2     = 0
Set WPUA3     = 1 'OK
Set WPUA4     = 1 'I2C_Dat
Set WPUA5     = 1 'I2C_Clk

Set WPUb4     = 0
Set WPUb5     = 0
Set WPUb6     = 0
Set WPUb7     = 1 'P10

Set WPUc0     = 0
Set WPUc1     = 1 'P15
Set WPUc2     = 1 'P14
Set WPUc3     = 1 'StSw
Set WPUc4     = 1 'Up
Set WPUc5     = 1 'Dn
Set WPUc6     = 1 'EnSw
Set WPUc7     = 1 'P9

#Include <DS3231.h>
'Define I2C settings - S/W I2C
#Define I2C_MODE Master
#Define I2C_DISABLE_INTERRUPTS On

#Define I2C_CLOCK       PortA.5 'Pin 2
#Define I2C_DATA        PortA.4 'Pin 3

#Define OkSw            PortA.3 'Pin 4 In only
#Define DnSw            PortC.5 'Pin 5
#Define UpSw            PortC.4 'Pin 6

'These switches are made active when the pointer on the stepper motor contacts
'with pins on the clockface. The pointer has solder points on it to attach a
'loop of wire which is fabricated to short out the pins protruding from the clock
'face. The start switch (at zero minutes) should be arranged to make contact when
'the pointer is aligned with the zero minute marker. The end switch (at sixty
'minutes) should be arranged so that it makes contact when the pointer has just
'passed the sixty minute marker.
#Define StSw            PortC.3 'Pin 7
#Define EnSw            PortC.6 'Pin 8
'These switches are made active when the pointer on the stepper motor contacts
'with pins on the clockface. The pointer has solder points on it to attach a
'loop of wire which is fabricated to short out the pins protruding from the clock
'face. The start switch (at zero minutes) should be arranged to make contact when
'the pointer is aligned with the zero minute marker. The end switch (at sixty
'minutes) should be arranged so that it makes contact when the pointer has just
'passed the sixty minute marker.

#Define P9              PortC.7 'Pin 9
#Define P10             PortB.7 'Pin 10

#Define D_Lat           PortB.6 'Pin 11
#Define D_Data          PortB.5 'Pin 12
#Define D_Clk           PortB.4 'Pin 13

#Define P14             PortC.2 'Pin 14
#Define P15             PortC.1 'Pin 15

#Define MtrD            PortC.0 'Pin 16
#Define MtrC            PortA.2 'Pin 17
#Define MtrB            PortA.1 'Pin 18
#Define MtrA            PortA.0 'Pin 19

#Define E_Hands         1
#Define E_DS3231        2
#Define E_Other1        3
#Define E_Other2        4
#Define Blank           5

#Define S_Hrs           20 'Hours
#Define S_Mns           21 'Minutes

#Define Dp_Hr           2
#Define Dp_Mn           1

Dir     OkSw            In
Dir     DnSw            In
Dir     UpSw            In

'These switches are made active when the pointer on the stepper motor contacts
'with pins on the clockface. The pointer has solder points on it to attach a
'loop of wire which is fabricated to short out the pins protruding from the clock
'face. The start switch (at zero minutes) should be arranged to make contact when
'the pointer is aligned with the zero minute marker. The end switch (at sixty
'minutes) should be arranged so that it makes contact when the pointer has just
'passed the sixty minute marker.
Dir     StSw            In
Dir     EnSw            In
'These switches are made active when the pointer on the stepper motor contacts
'with pins on the clockface. The pointer has solder points on it to attach a
'loop of wire which is fabricated to short out the pins protruding from the clock
'face. The start switch (at zero minutes) should be arranged to make contact when
'the pointer is aligned with the zero minute marker. The end switch (at sixty
'minutes) should be arranged so that it makes contact when the pointer has just
'passed the sixty minute marker.

Dir     D_Clk           Out
Dir     D_Data          Out
Dir     D_Lat           Out
Dir     MtrA            Out
Dir     MtrB            Out
Dir     MtrC            Out
Dir     MtrD            Out

'Variables used

Dim     Dat             As Word
Dim     Temp            As Byte
Dim     Clocks          As Byte
Dim     Digit           As Byte


Dim     D1              As Word
Dim     D2              As Word
Dim     D3              As Word
Dim     D4              As Word
Dim     Dt              As Word

Dim CountedMv As Word

Dim CENTURY_FLAG    As Byte
Dim POWERLOSS       As Byte

Dim Changed         As Bit
Dim Hour            As Byte
Dim Min             As Byte
Dim Sec             As Byte
Dim Am_Pm           As Byte


Dim TimeT           As Byte
Dim Target          As Word
Dim LastHour        As Word
Dim LastMin         As Word

Dim Date            As Byte
Dim Month           As Byte
Dim Year            As Byte
Dim DOW             As Byte
Dim Century         As Byte

Dim DecimalPoint    As Byte

Dim TempMSB         As Byte
Let TempMSB = 0
'Dim TempLSB         As Byte
'Let TempLSB = 0
Dim Minus           As Bit
Let Minus = 0

Let CountedMv = 0

'Whenever the time and date are saved, the date is reset to the compile date
'As the date is never seen, we don't care about the date!
#Define CompileDay  5  'Friday
#Define CompileDate 21 '21st
#define CompileMnth 5  'May
#Define CompileYear 21 '2021
'Whenever the time and date are saved, the date is reset to the compile date
'As the date is never seen, we don't care about the date!


#Define DelTime 2000  ' 2mS per step
Dim StepSequence    As Byte

Start_Up_Sub

Start_Of_Program:

Do

    GetTime

    If DnSw = 0 Then
        ShowValuesSub(Min,Dp_Mn)
        Wait 1000 mS
    End If

    If UpSw = 0 Then
        GetTemperature
        'If the temperature is below zero, this will not be indicated!
        ShowValuesSub(TempMSB,0)
        'If the temperature is below zero, this will not be indicated!
        Wait 1000 mS
    End If

    If OkSw = 0 Then
        Wait 500 mS
        If OkSw = 0 Then
            GetTime
            Let LastMin  = Min
            Let LastHour = Hour
            Set_Time

            If LastMin <> Min Then
                Let Sec = 0 'Zero the seconds
                SaveTimeDate
            Else
                If LastHour <> Hour Then
                    Let LastHour = Hour 'Only save the hour
                    GetTime
                    Let Hour = LastHour
                    SaveTimeDate
                End If
            End If

        End If
    End If

    ValidateHour

    If PowerLoss = True Then
        If DecimalPoint = 2 Then
            Let DecimalPoint = 1
        Else
            Let DecimalPoint = 2
        End If
    Else
        Let DecimalPoint = 0
    End If
    ShowValuesSub(Hour,DecimalPoint)

' 1 minute * 52 = 52
' every 15 seconds move 13
' 3 * 13 = 39
' then at the new minute move 13 = 52 per minute
' 53 * 60 minutes = 3120
' angle of hands need 3120 steps to move from zero to sixty

    Let Target = Min * 52
    If Sec > 14 Then
        Let Target = Target + 13
    End If
    If Sec > 29 Then
        Let Target = Target + 13
    End If
    If Sec > 44 Then
        Let Target = Target + 13
    End If

    If CountedMv < Target Then
        Do
            Move_ClockWise(1)
            Let CountedMv = CountedMv + 1
        Loop Until CountedMv >= Target
    End If

    If CountedMv > Target Then 'May have adjusted time?
        Do
            MoveAClockWise(1)
            Let CountedMv = CountedMv - 1
        Loop Until CountedMv <= Target
    End If

    If Min > 58 Then
        If Sec > 53 Then 'It takes about 8 seconds to return
        '  by the time we're home, the new hour should start
            Let Target = 0
            Do
                MoveAClockWise(1)
            Loop Until StSw = 0
            Let CountedMv = 0
        End If
    End If

    If EnSw = 0 Then 'At end stop?
        Do
            MoveAClockWise(1)
        Loop Until StSw = 0
        Let CountedMv = 0
    End If

'It may be that after returning to zero, the pointer needs moving a few steps to align better with
'zero minutes?

'Hopefully this can be accounted for by adjusting the position of the "loop" on the pointer, but
'it may need some software "correction"?
Loop

Sub Move_ClockWise(In StepCnt As Word)

    Repeat StepCnt
        Select Case StepSequence
            Case 1
                Step1
            Case 2
                Step2
            Case 3
                Step3
            Case 4
                Step4
            Case 5
                Step5
            Case 6
                Step6
            Case 7
                Step7
            Case 8
                Step8
            Case Else
                Let StepSequence = 1
        End Select
        Let StepSequence = StepSequence + 1
        If StepSequence > 8 Then
            Let StepSequence = 1
        End If
    End Repeat

End Sub

Sub MoveAClockWise(In AStepCnt As Word)

    Repeat AStepCnt
        Select Case StepSequence
            Case 1
                Step8
            Case 2
                Step7
            Case 3
                Step6
            Case 4
                Step5
            Case 5
                Step4
            Case 6
                Step3
            Case 7
                Step2
            Case 8
                Step1
            Case Else
                Let StepSequence = 1
        End Select
        Let StepSequence = StepSequence + 1
        If StepSequence > 8 Then
            Let StepSequence = 1
        End If
    End Repeat

End Sub

'############################################################################################################
'The below two are not used here
Sub Spin_Clockwise(In SpinCount As Word)


    AllOff
    Repeat SpinCount

        Step1
        Step2
        Step3
        Step4
        Step5
        Step6
        Step7
        Step8

    End Repeat
    Let StepSequence = 1

End Sub

Sub SpinAClockwise(In ASpinCount As Word)

    AllOff
    Repeat ASpinCount

        Step8
        Step7
        Step6
        Step5
        Step4
        Step3
        Step2
        Step1

    End Repeat
    Let StepSequence = 1

End Sub
'The above two are not used here
'#############################################################################################################

Sub AllOff
    Let MtrA = 0
    Let MtrB = 0
    Let MtrC = 0
    Let MtrD = 0
End Sub

Sub Step1
    Let MtrD = 1
    Wait DelTime uS

    AllOff
End Sub

Sub Step2
    Let MtrD = 1
    Let MtrC = 1
    Wait DelTime uS

    AllOff
End Sub

Sub Step3
    Let MtrC = 1
    Wait DelTime uS

    AllOff
End Sub

Sub Step4
    Let MtrC = 1
    Let MtrB = 1
    Wait DelTime uS

    AllOff
End Sub

Sub Step5
    Let MtrB = 1
    Wait DelTime uS

    AllOff
End Sub

Sub Step6
    Let MtrB = 1
    Let MtrA = 1
    Wait DelTime uS

    AllOff
End Sub

Sub Step7
    Let MtrA = 1
    Wait DelTime uS

    AllOff
End Sub

Sub Step8
    Let MtrD = 1
    Let MtrA = 1
    Wait DelTime uS

    AllOff
End Sub


Sub ShowValuesSub(In D_Value As Word, In DP_On As Byte)

    Let Dt = D_Value

    If Dt > 99 Then
        Do
            Let Dt = Dt / 10
        Loop Until Dt < 100
    End If

    Let D1 = 255 'Space - There is only a two digit display!
    Let D2 = 255 'Space - There is only a two digit display!

    If Dt > 9 Then  '10s
       Let D3 = Dt / 10
       Let Dt = Dt - (10*D3)
       Let D3 = D3 + 1 'Lookup starts at 0
    Else
       Let D3 = 1    'Zero
    End If

    Let D4 = Dt + 1 '1s

    If D3 < 255 Then
       ReadTable Numerals, D3, Dt
       Let D3 = Dt
    End If
    If D4 < 255 Then
       ReadTable Numerals, D4, Dt
       Let D4 = Dt
    End If

    If Dp_On = Dp_Hr Then
        Let D3 = D3 - 128
    End If
    If Dp_On = Dp_Mn Then
        Let D4 = D4 - 128
    End If

    Let D_Lat  = 0                'Start output data latch
    ShiftData(D1) '1000s
    ShiftData(D2) '100s
    ShiftData(D3) '10s
    ShiftData(D4) '1s
    Let D_Lat  = 1                'End output data latch

End Sub

Sub ClearDisplay
    For Temp=1 to 4
        SendSpace
    Next Temp
End Sub

Sub SendSpace

    Let D_Lat  = 0                'Start output data latch
    Let D_Data = 1

    For Clocks = 1 to 8
      Let D_Clk = 0                'Shift register clocked
      Wait 1 uS
      Let D_Clk = 1
    Next Clocks
    Let D_Lat  = 1                'End output data latch

End Sub

Sub ShiftData (DataOut As Byte)

    For Clocks = 1 to 8
      Let D_Clk = 0               'Shift register clocked
      Let D_Data = DataOut.7
      Let D_Clk = 1
      Rotate DataOut Left Simple
    Next Clocks

End Sub

Sub ErrorSub(In E_Type As Byte)

    Do
        ShowMessage(E_Type)
        Wait 500 mS
        ShowMessage(Blank)
        Wait 500 mS
    Loop

End Sub

'A  136
'B  128 b 131
'C  198 c 167
'D  192 d 161
'E  134
'F  142
'G  194
'H  137 h 139
'I  207 i 239
'J  241
'K  137 k 139
'L  199
'M  200 248 n,n 171 187
'N  200     n   171
'O  192 o 163
'P  140
'q  152
'R  206 r 175
'S  146
't  135
'U  193 u 227
'V  193 v 227
'W  193 241 w 227 243
'X  137
'Y  145
'Z  164
'Deduct 128 from a value to show a decimal point
'
'0  192
'1  249
'2  164
'3  176
'4  153
'5  146
'6  130
'7  248
'8  128
'9  152
'Deduct 128 from a value to show a decimal point

Sub ShowMessage(In Message As Byte)

    If Message = E_Hands Then
        Let D_Lat  = 0                'Start output data latch
        ShiftData(255) 'Space
        ShiftData(255) 'Space
        ShiftData(134) 'E
        ShiftData(137) 'H
        Let D_Lat  = 1                'End output data latch
    End If

    If Message = E_DS3231 Then
        Let D_Lat  = 0                'Start output data latch
        ShiftData(255) 'Space
        ShiftData(255) 'Space
        ShiftData(134) 'E
        ShiftData(198) 'C
        Let D_Lat  = 1                'End output data latch
    End If

    If Message = E_Other1 Then
        Let D_Lat  = 0                'Start output data latch
        ShiftData(255) 'Space
        ShiftData(255) 'Space
        ShiftData(134) 'E
        ShiftData(249) '1
        Let D_Lat  = 1                'End output data latch
    End If

    If Message = E_Other2 Then
        Let D_Lat  = 0                'Start output data latch
        ShiftData(255) 'Space
        ShiftData(255) 'Space
        ShiftData(134) 'E
        ShiftData(164) '2
        Let D_Lat  = 1                'End output data latch
    End If

    If Message = Blank Then
        Let D_Lat  = 0                'Start output data latch
        ShiftData(255) 'Space
        ShiftData(255) 'Space
        ShiftData(255) 'Space
        ShiftData(255) 'Space
        Let D_Lat  = 1                'End output data latch
    End If

End Sub

Sub ShowVersion

    ShowValuesSub(CompileDate,0)
    Wait 1000 mS
    ShowValuesSub(ComPileMnth,0)
    Wait 1000 mS
    ShowValuesSub(CompileYear,0)
    Wait 1000 mS

End Sub

Sub Start_Up_Sub
    AllOff
    ClearDisplay 'Wipe the LED Display

    ShowVersion

'It may be that after returning to zero, the pointer needs moving a few steps to align better with
'zero minutes?

'Hopefully this can be accounted for by adjusting the position of the "loop" on the pointer, but
'it may need some software "correction"?

    Do
        Do
            MoveAClockWise(1)
            Let CountedMv = CountedMv + 1
            ShowValuesSub(CountedMv,0)
            If CountedMv > 3500 Then
                ErrorSub(E_Hands)
            End If
        Loop Until StSw = 0
        Let CountedMv = 0
        ShowValuesSub(CountedMv,0)
        Wait 1000 mS
        Do
            Move_ClockWise(1)
            Let CountedMv = CountedMv + 1
            ShowValuesSub(CountedMv,0)
            If CountedMv > 3500 Then
                ErrorSub(E_Hands)
            End If
        Loop Until EnSw = 0
        ShowValuesSub(CountedMv,0)
        Wait 1000 mS
    Loop Until CountedMv > 2999

    Let CountedMv = 0
    Do
        MoveAClockWise(1)
        Let CountedMv = CountedMv + 1
        ShowValuesSub(CountedMv,0)
        If CountedMv > 3500 Then
            ErrorSub(E_Hands)
        End If
    Loop Until StSw = 0

    Let StepSequence = 1
    Let CountedMv = 0
    ShowValuesSub(CountedMv,0)

'It may be that after returning to zero, the pointer needs moving a few steps to align better with
'zero minutes?

'Hopefully this can be accounted for by adjusting the position of the "loop" on the pointer, but
'it may need some software "correction"?

    Initialise_I2C
    Start_DS3231

    GetTime 'Show the time stored in DS3231
    ValidateHour
    ShowValuesSub(Hour,Dp_Hr)
    Wait 1000 mS
    ShowValuesSub(Min,Dp_Mn)
    Wait 1000 mS

End Sub

Table Numerals as Byte
    192 '0
    249 '1
    164 '2
    176 '3
    153 '4
    146 '5
    130 '6
    248 '7
    128 '8
    144 '9
End Table

Table MonthDays ;# of days in Months
    31
    29 ;leap years only
    31
    30
    31
    30
    31
    31
    30
    31
    30
    31
End Table

Sub Start_DS3231

'   aging offset' Zero compensation added here
    DS3231_WriteRegister ( 0x10, 0b0000000 )

    GetDate
    If Century_Flag = 1 Then
       DS3231_HandleCentury ( Century_Flag, Century )
    End If

    DS3231_SetHourMode(24)                    '24-Hour mode

    DS3231_EnableOscillator( True )           'and, ensure the clock is running

    DS3231_Set32kHz ( True )                  'and, enable the 32kHz Output (EN32kHz).
    DS3231_EnableSQW
    DS3231_SetSQW 0                           'and, turn ON output as we will use as the alarm port!
    DS3231_DisableSQW

    DS3231_DisableAlarm1
    DS3231_DisableAlarm2

    'initialise a tracking variable
    powerloss = False

End Sub

Sub Check_DS3231_Status
    If DS3231_OscillatorStopFlagStatus = True Then ' has a power loss occurred? and the oscillator has stopped?
      Let powerloss = True
      DS3231_ClearOscillatorStopFlag
    End If
End Sub

Sub Initialise_I2C
  #IfDef I2C_DATA
        I2CStart                          ' is DS3231 present?
        I2CSend(DS_AddrWrite)
        I2CStop

        Let D_Lat  = 0                'Start output data latch
        ShiftData(255) 'Space
        ShiftData(255) 'Space
        ShiftData(207) 'I
        ShiftData(198) 'C
        Let D_Lat  = 1                'End output data latch
        Wait 250 mS

        If I2CSendState = False  Then     ' is DS3231 present?
           ErrorSub(E_DS3231)
        End If
  #EndIf
End Sub

Sub GetTime
    DS3231_ReadTime(Hour, min, sec, am_pm)
    If Hour > 23 Then
        Let Hour = 0
    End If
    If Min > 59 Then
        Let Min = 0
    End If
    If Sec > 59 Then
        Let Sec = 0
    End If
End Sub

Sub GetDate
    DS3231_ReadDate(DOW, Date, Month, Year, Century_Flag )   'get initial date

    If Century_Flag = 1 Then
       DS3231_HandleCentury ( Century_Flag, Century )
    End If

    If DOW > 7 Then
        Let DOW = 1
    End If
    If DOW < 1 Then
        Let DOW = 1
    End If

    If Date > 31 Then
        Let Date = 1
    End If
    If Date < 1 Then
        Let Date = 1
    End If

    If Year > 99 Then
        Let DOW = 21
    End If
    If Year < 1 Then
        Let Year = 21
    End If
End Sub

Sub Set_Time

    ValidateHour

    Do
        ShowValuesSub(Hour,Dp_Hr)
        Wait 100 mS
    Loop Until OkSw = 1

    Wait 500 mS

    Do
        ShowValuesSub(Hour,Dp_Hr)
        If UpSw = 0 Then
            Let Hour = Hour + 1
            If Hour > 12 Then
                Let Hour = 1
            End If
        End If
        If DnSw = 0 Then
            Let Hour = Hour - 1
            If Hour < 1 Then
                Let Hour = 12
            End If
        End If
        Wait 250 mS
    Loop Until OkSw = 0
    Do
        ShowValuesSub(Min,Dp_Mn)
        Wait 100 mS
    Loop Until OkSw = 1

    Wait 500 mS

    Do
        ShowValuesSub(Min,Dp_Mn)
        If UpSw = 0 Then
            Let Min = Min + 1
            If Min > 59 Then
                Let Min = 0
            End If
        End If
        If DnSw = 0 Then
            Let Min = Min - 1
            If Min > 59 Then
                Let Min = 59
            End If
        End If
        Wait 250 mS
    Loop Until OkSw = 0
    Do
        Wait 100 mS
    Loop Until OkSw = 1

End Sub

Sub SaveTimeDate

'Whenever the time and date are saved, the date is reset to the compile date
'As the date is never seen, we don't care about the date!
    Let DOW   = CompileDay
    Let Date  = CompileDate
    Let Month = CompileMnth
    Let Year  = CompileYear
'Whenever the time and date are saved, the date is reset to the compile date
'As the date is never seen, we don't care about the date!

    DS3231_SetHourMode(24)
    DS3231_SetClock(Hour, Min, Sec, DOW, Date, Month, Year)
    powerloss  = False ' reset tracker variable
    DS3231_ClearOscillatorStopFlag

End Sub

Sub ValidateHour
    If Hour > 12 Then 'Not interested in 24Hr clock
        Let Hour = Hour - 12
    End If
    If Hour = 0 Then
        Let Hour = 12
    End If
End Sub

Sub GetTemperature

    Let TempMSB = DS3231_ReadRegister(0x11)
'    Let TempLSB = DS3231_ReadRegister(0x12)

    If TempMSB > 127 Then 'Minus value
        Let Minus = 1
        Let TempMSB = TempMSB - 128
    Else
        Let Minus = 0
    End If

'    Select Case TempLSB
'    Case 0
'        Let TempLSB = 0
'    Case 64
'        Let TempLSB = 25
'    Case 128
'        Let TempLSB = 50
'    Case 192
'        Let TempLSB = 75
'    Case Else
'        Let TempLSB = 0
'    End Select

End Sub

[Anobium]

Great project! Well done. I love the video!

---

Recommendation in the source. Rename ERROR() to ERRORHANLDER(). I later version of the compiler ERROR is a reserved word.

And, I just compiled your program using PIC-AS compiler. Works - I am very happy. :-) Means the PIC-AS compiler with MPLAB-IDE works.

[mkstevo]

Thanks for that. I'll get that changed.

[stan cartwright]

That is impressive..well I like it.
I think a rc servo could turn 270 degrees and do similar...for a minute timer.
rc servos are just send pulseout to control position and a timer interrupt for the clock.
I'm a tight hobbyist and always look for the cheapest solution...yeah..sad but c'est moi.

My ambition is a small glcd that looks like 4 valve numeric displays. nixie tubes?

[mkstevo]

I looked at the 270 degree servos. They would have been ideal, but found the application notes rather ambiguous to say the least. The tiny geared stepper motor was much more predictable, and very inexpensive. I think three cost me £3, shipped from China.

I have a fake "Nixie" which uses LCDs to simulate the "Nixie" tubes. It is very good. I also have a real "Nixie" clock, it looks more realistic than the fake one (as it should) but if you'd never seen a real one, you would be happy with the fake.

Fake vs. real...

[stan cartwright]

If of interest I have a frequency counter that uses nixie tubes but the top of valve jobs for display.
Nostalgia is they were a pain to drive... but looked cool before leds were invented.

[mkstevo]

They needed a high-ish voltage to strike the glow, but I don't think they were a particular pain to drive? And they do look good.

[stan cartwright]

rc servos ie 1 wire,gnd,supply are easy with gcb.
I use them on my bots for moving the distance sensor and taken them apart to make them
rotate continuously.
You know the position from the pulseout sent.
although not documented in gcb, if you attach a wire to the rc servo potentiometer wiper and connect to a-d pin then you can measure the servo position even when not powered.
I could teach my thing to move fom a manuallu set pattern...maybe.

[mkstevo]

I couldn't get my head to work out how to move the servos to single (or partial) degree accuracy. I also found that some of them were 180 degree servos, extended in some way which might, or might not, have the capacity to move the full 270 degree range. They were my first choice as I would have liked the speed.

My second choice was some DC motors, geared with position sensors. They looked better, but were larger and more expensive.

The geared stepper motors did at least have the capability of moving the full range I needed. They do sometimes not move the full steps expected, which is why I fitted the "limit switches". With these "limit switches" on the face, should the hand get nudged out of position or fail to move the full number of steps, it will be corrected either when the hand gets to sixty minutes early, or when the new hour starts and the hand returns to the zero position.

[stan cartwright]

They both look real,
edit...the nixie tubes photos
There's different ways of pulsing stepper motors. the more phases the smaller the movement.
I used full wave to get max speed from the geared https://www.ebay.co.uk/itm/201999043536?chn=ps&norover=1&mkevt=1&mkrid=710-134428-41853-0&mkcid=2&itemid=201999043536&targetid=1140163974409&device=c&mktype=pla&googleloc=9045370&poi=1007436&campaignid=12689628172&mkgroupid=118339815297&rlsatarget=pla-1140163974409&abcId=9300529&merchantid=118951391&gclid=CjwKCAjw-qeFBhAsEiwA2G7Nl1i3cnSCSloGyLnG8lLTGWV4VmFbCWnhl2lHzoDbf4B5VhLoFbiLaRoCoQwQAvD_BwE
you don't need peed but resolution.

[mkstevo]

I am using eight steps (micro stepping?) for the motors. This coupled with the gearing, means I need close to 3,200 steps for my 270 degrees between zero and sixty minutes.

[mkstevo]

I've added two further videos for those who don't have much to do...

The first video shows the clock transitioning from 1.59 pm to 2.00 pm, it only lasts 30 seconds so won't take long to watch.

Short version

The second video shows (almost) an entire hour, 2pm - 3pm in time lapse. Shooting it in time lapse means it doesn't take a whole hour, it does take sixteen minutes though. Still, if you've got nothing better to do...

One hour compressed into sixteen minutes