Seven Segment Display

I was reading about seven segment displays over at Sparkfun and thought it would be a fun exercise in Excel. I’m sure it’s been done a million times, but not by me. The first one was VBA based. Type a number into a cell and this code fills cells to display the number as a seven segment display.

Public Sub ShowSevenSegment(ByVal lInput As Long)

Dim sValue As String
Dim i As Long, j As Long
Dim aDigits(0 To 9) As Variant
Dim aRange() As String
Dim aRow(0 To 6) As Long, aCol(0 To 6) As Long
Dim rSeg As Range

Const lDISPCNT As Long = 4
Const lON As Long = vbBlack
Const lOFF As Long = vbWhite

'Hold the top left cell for each display
ReDim aRange(1 To lDISPCNT)

'Set the on/off for each digit. The order is top, left top,
'right top, middle, left bottom, right bottom, bottom
aDigits(0) = Array(lON, lON, lON, lOFF, lON, lON, lON)
aDigits(1) = Array(lOFF, lOFF, lON, lOFF, lOFF, lON, lOFF)
aDigits(2) = Array(lON, lOFF, lON, lON, lON, lOFF, lON)
aDigits(3) = Array(lON, lOFF, lON, lON, lOFF, lON, lON)
aDigits(4) = Array(lOFF, lON, lON, lON, lOFF, lON, lOFF)
aDigits(5) = Array(lON, lON, lOFF, lON, lOFF, lON, lON)
aDigits(6) = Array(lON, lON, lOFF, lON, lON, lON, lON)
aDigits(7) = Array(lON, lOFF, lON, lOFF, lOFF, lON, lOFF)
aDigits(8) = Array(lON, lON, lON, lON, lON, lON, lON)
aDigits(9) = Array(lON, lON, lON, lON, lOFF, lON, lON)

'Set the offset from the top left cell for each of the
'seven segments
aRow(0) = 0: aCol(0) = 1
aRow(1) = 1: aCol(1) = 0
aRow(2) = 1: aCol(2) = 2
aRow(3) = 2: aCol(3) = 1
aRow(4) = 3: aCol(4) = 0
aRow(5) = 3: aCol(5) = 2
aRow(6) = 4: aCol(6) = 1

'Set the top left cell for each display
For i = 1 To lDISPCNT
aRange(i) = Sheet1.Range("B2").Offset(0, (i - 1) * 4).Address
Next i

'Truncate and pad the value as necessary
If lInput > (10 ^ lDISPCNT) - 1 Then
sValue = Left$(lInput, lDISPCNT)
Else
sValue = Format(lInput, String(lDISPCNT, "0"))
End If

'Clear everything
Sheet1.Range(aRange(1)).Resize(5, 15).Interior.Color = lOFF

'Loop though the digits
For i = 1 To Len(sValue)
'Loop through the on/offs for that digit
For j = LBound(aDigits(CLng(Mid$(sValue, i, 1)))) To UBound(aDigits(CLng(Mid$(sValue, i, 1))))
'get the segment range and set the color
Set rSeg = Sheet1.Range(aRange(i)).Offset(aRow(j), aCol(j))
rSeg.Interior.Color = aDigits(CLng(Mid$(sValue, i, 1)))(j)

'color the corners
If aDigits(CLng(Mid$(sValue, i, 1)))(j) = lON Then
'for horizontal segments, fill left and right
If rSeg.Width > rSeg.Height Then
rSeg.Offset(0, -1).Interior.Color = lON
rSeg.Offset(0, 1).Interior.Color = lON
Else
'for vertical segments, fill up and down
rSeg.Offset(-1, 0).Interior.Color = lON
rSeg.Offset(1, 0).Interior.Color = lON
End If
End If
Next j
Next i

End Sub

OK, it’s really a 13 segment display – the seven segments and six connecting cells. Next, I did the same thing with conditional formatting. I tried to make the conditional formatting formula consistent across the cells, but I just couldn’t. The TRUEs and FALSEs change for each cell depending on if that cell is lit for that number.

Here’s the CF formula for cell H3.

=CHOOSE(MID(TEXT($C$9,"0000"),(COLUMN()+MOD(MOD(MOD(16-COLUMN(),12),8),4))/4,1)+1,TRUE,TRUE,TRUE,TRUE,TRUE,FALSE,FALSE,TRUE,TRUE,TRUE)

H3 is lit for every number except 5 and 6. There’s data validation on the input cell to keep it under five digits. The CF formula is a CHOOSE function with nine TRUEs/FALSEs. To determine which character to represent, I use a MID function after padding the text to four digits. The starting position (second argument of MID) is determine by this:

(COLUMN()+MOD(MOD(MOD(16-COLUMN(),12),8),4))/4,1)

Column 16-Column Mod 12 Mod 8 Mod 4 Column+ /4
2 14 2 2 2 4 1
3 13 1 1 1 4 1
4 12 0 0 0 4 1
6 10 10 2 2 8 2
7 9 9 1 1 8 2
8 8 8 0 0 8 2
10 6 6 6 2 12 3
11 5 5 5 1 12 3
12 4 4 4 0 12 3
14 2 2 2 2 16 4
15 1 1 1 1 16 4
16 0 0 0 0 16 4

You can download SevenSegment.zip

4 thoughts on “Seven Segment Display

  1. This is a great exercise! I appreciate that you showed multiple approaches as it is always good to see things from multiple angles. I decided to take up your exercise and try my hand at it.

    I setup a truth table for the numbers, so I could separate that out from the conditional formatting formulas, and looked up the appropriate 1/0 for each number character from the table. Now all I need is one CF formula of Cell Value = 1 to handle all of the cells formulas.

    No matter whether the complexity is in the CF formula or on the sheet, it seems that we can’t avoid all of it. It would be interesting to see if any simpler solutions arise from this.

  2. The following single Change event procedure (no other code nor any conditional formatting required) will produce the same results as your posted setup (I have assume the column and row width have been set to their desired widths and heighths)…

    Private Sub Worksheet_Change(ByVal Target As Range)
    Dim X As Long, CellVal As Variant, Digit As Range
    If Target.Address = Me.Range("C9").Address Then
    CellVal = Target.Value
    If CellVal Like "*[!0-9]*" Then
    MsgBox "The value you entered is not valid!", vbCritical
    Application.EnableEvents = False
    Application.Undo
    Application.EnableEvents = True
    Else
    CellVal = Format(CellVal + 0, "0000")
    Application.ScreenUpdating = False
    For X = 0 To 3
    With Range("B2").Offset(, 4 * X)
    .Resize(5, 3).Interior.ColorIndex = 1
    Select Case Mid(CellVal, 1 + X, 1)
    Case 0: .Offset(1, 1).Resize(3, 1).Interior.ColorIndex = 0
    Case 1: .Resize(5, 2).Interior.ColorIndex = 0
    Case 2: .Offset(1, 0).Resize(1, 2).Interior.ColorIndex = 0
    .Offset(3, 1).Resize(1, 2).Interior.ColorIndex = 0
    Case 3: .Offset(1, 0).Resize(1, 2).Interior.ColorIndex = 0
    .Offset(3, 0).Resize(1, 2).Interior.ColorIndex = 0
    Case 4: .Offset(0, 1).Resize(2, 1).Interior.ColorIndex = 0
    .Offset(3, 0).Resize(2, 2).Interior.ColorIndex = 0
    Case 5: .Offset(1, 1).Resize(1, 2).Interior.ColorIndex = 0
    .Offset(3, 0).Resize(1, 2).Interior.ColorIndex = 0
    Case 6: .Offset(1, 1).Resize(1, 2).Interior.ColorIndex = 0
    .Offset(3, 1).Resize(1, 1).Interior.ColorIndex = 0
    Case 7: .Offset(1, 0).Resize(4, 2).Interior.ColorIndex = 0
    Case 8: .Offset(1, 1).Resize(1, 1).Interior.ColorIndex = 0
    .Offset(3, 1).Resize(1, 1).Interior.ColorIndex = 0
    Case 9: .Offset(1, 1).Resize(1, 1).Interior.ColorIndex = 0
    .Offset(3, 0).Resize(1, 2).Interior.ColorIndex = 0
    End Select
    End With
    Next
    Application.ScreenUpdating = True
    End If
    End If
    End Sub

  3. That’s a lot of code to accomplish a simple task.
    A oneliner will do.

    With conditional formatting in the range A1:O5 the result will be shown as in Dick’s example.
    Formatting conditions:
    – when a cell is not empty than black for the seven elements (A2,A4,B1,B3,B5,C2,C4);
    – if the adjacent cells are not empty then black for the corner cells between the seven elements (A1,A3,A5,C1,C3,C5). This formatting extended to the Range A1:O5.

    In the code I use an asterisk for illustration purposes; I’d prefer to use a space instead.
    The number to be shown is in cell A30 (at least in the code below).


    Sub M_snb()
    If Len(Format(Val(Cells(30, 1)))) <> 4 Then Exit Sub
    [A1:O5] = [if(iserror(find(address(row(A1:O5),mod(column(A1:O5)-1,4)+1,4),choose(mid(A30,int(column(A1:O5)/4)+1,1)+1,"A2A4B1B5C2C4","C2C4","B1C2B3A4B5","B1C2B3C4B5","A2B3C2C4","A2B1B3C4B5","A2A4B3C4B5","B1C2C4","A2A4B1B3B5C2C4","A2B1B3C2C4"))),"","*")]
    End Sub

  4. Nice (although I wouldn’t want to maintain it). Next iteration. Put this formula in A1, then fill right and down to 05.

    =IF(ISERROR(FIND(ADDRESS(ROW(),MOD(COLUMN()-1,4)+1,4),CHOOSE(MID(TEXT($B$30,"0000"),INT(COLUMN()/4)+1,1)+1,"A1A2A3A4A5B1B5C1C2C3C4C5","C1C2C3C4C5","A1A3A4A5B1B3B5C1C2C3C5","A1A3A5B1B3B5C1C2C3C4C5","A1A2A3B3C1C2C3C4C5","A1A2A3A5B1B3B5C1C3C4C5","A1A2A3A4A5B1B3B5C1C3C4C5","A1B1C1C2C3C4C5","A1A2A3A4A5B1B3B5C1C2C3C4C5","A1A2A3B1B3C1C2C3C4C5"))),"","*")

    Then put CF on A1:05 like this

    =A1="*"

    I moved in the input cell to column B because it was wider. The download file will be updated to include @snb’s VBA solution and this one.

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