7-Segment Display Project

Task: To make and program a 7-segment display
Difficulty: Intermediate (building)

For this project you will need:

  • A computer running the Crumble software
  • A Crumble with USB lead,
  • Seven Sparkles
  • 23 Croc-leads
  • The template (If using)
  • Card
  • Scissors
  • Glue

1 Get your resources ready.

2 Cut the centre parts of the segments out.

3 Cut out the strips from the template.

4 Mark out where to fold your segment sides.

5 After folding the strip, start to glue it perpendicular to the base.

6 Continue gluing the strip along the edge.

7 When you reach the end point, if you haven’t already, trim the excess off.

8 Add some glue into the corner to secure it.

9 Continue the process until each segment is complete.

10 Using the rest of the card strips, create a border.

11 Continue gluing the card around the edge until it’s complete.

12 Now cut four strips of card, around 1cm x 5cm.

13 Glue the tops of the four strips, along the bottom of the back.

14 Then glue the strips to the base.

15 Flip your display over, with 0 at the top.

16 Place a Sparkle into the slot you cut previously.

17 Make a note of the labels and the direction. This will help with the wiring. Repeat for all 7 Sparkles.

18 Now cut yourself seven strips of card, about 1 x 8 cm.

19 Place a blob of glue above and below the Sparkle.

20 Stick the strip of card down to hold the Sparkle in place.

21 Repeat for all seven Sparkles.

22 Starting at Sparkle 0, start wiring it up.

23 Working in a spiral (0-6), or a number 6 shape, wire up all of the Sparkles.

24 Connect your display to your Crumble (+, – and D) and wire up your battery box (+ to + and – to -).

25 Now take a sheet of A3 paper/tissue paper.

26 Place your display face down onto the middle of the paper, and lightly draw around it.

27 Now draw a rough tab shape on each edge.

28 You should end up with a shape like this.

29 Now cut the shape out.

30 To work out which Sparkles need to be lit for each number, we filled in our worksheet.

31 To start with, make the number zero. It’s as simple as lighting the relevant Sparkles.

32 To allow us to easily change the colours, you can use the RGB blocks.

33 You can then globally set the values using three variables.

34 To make a countdown timer, it’s as simple as making a number, waiting one second, clearing the Sparkles and making the next number. This is then put inside a loop so the 9 second countdown repeats. Although the code may look daunting, it is really is easy!

35 To extend this further, we can wire a switch to control the timer. Connect one end to A, and the other to a + on the battery pack.

36 Then to use this, we only need to add two extra blocks. We clear the Sparkles before waiting until A is HI.

And there you have it. Your very own giant 7-segment display, ready to countdown or keep track of scores. What will you do with yours?

Links to the curriculum:


  • Design, write and debug programs that accomplish specific goals, including controlling or simulating physical systems;
  • Solve problems by decomposing them into smaller parts;
  • Use sequence, selection and repetition in programs; work with various forms of input and output.

Design and technology:

  • Apply their understanding of computing to program, monitor and control their products.


  • Can be linked to problem-solving investigations using 7-segment, calculator style displays. A typical example is the investigation involving match sticks.