This project is a WordNum clock being a hybrid of a Wordclock and a digital clock using 100 addressible RGB LED's controlled by a Microbit with an RTC.

Displaying the time in 12 hour mode and updated each minute with the addition of text each 5 minutes.

The display and main supporting structure is 3D printed and optionally can be mounted within a deep picture frame.

The display grid consists of 59 numbers, 40 letters and 1 symbol (+), backlit with 100 addressable RGB LED's on a 10 x 10 grid all controlled by a Microbit.

The numbers enable time combinations that exclude the five minute time intervals whilst the letters display the five minute intervals. In addition to the meridiem's represented by A for AM and P for PM.

The layout is such that the numbers may appear haphazard therefore to clarify its type, colour coding is applied.

Subject to user preference or vision colour perception other colours may be used.

The hours are displayed in green the minutes are displayed in red and the meridiem's in blue.

Example times.

14:00 becomes 2 OCLOCK P

14:10 becomes TEN PAST 2 P

03:45 becomes QUARTER TO 4 A

07:09 becomes 7 9 A

20:19 becomes 8 19 P

Size: 206(L) x 206(W) x 40(H) mm (excluding framing).

Currrent: <=200mA at 5V

Supplies

Microbit V2 (preferred due to built in speaker, V1 will work but will require an external sounder and code modification.)

Expansion Board for Microbit

DS3231 RTC

Switch DPDT

470R resistor

1000uF capacitor

Flexible RGB LED Strip (aka NeoPixel, WS2812, SK6812), 60 LED's/mtr - Qty 100 LED's.

Brass welding rods 250(L) x 1.6(dia) mm - Qty 8

Pin headers - Straight through hole single row

Jumpers Long Pin to Pin

30 AWG wrapping wire [if utilising wire wrapping]

Countersink screws (non metallic), M3 x 30mm - Qty 7

Pan head screw (non metallic), M3 x 25mm

Pan head screws (non metallic) M4 X 10mm - Qty 2

M2 x 10mm pan machine screws - Qty 3

M2 nuts - Qty 3

Threaded M2 x 5mm threaded spacers - Qty 3

ECW 21 AWG (0.7229(dia) mm)

Acrylic Sheet 5mm thick (White)

Acrylic sheet 3mm thick (Clear)

Print Details

Filament: PLA (Black : Character Display & Grid, White: Diffuser and Grey: Back)

Layer Height: 0.15mm

Infill: 100%

Bed Adhesion: Skirt

No supports

All parts are correctly orientated within the files for printing directly.

Circuit

The circuit elements consist of a Microbit V2, DS3231 RTC, Expansion Board, 100 Neopixel LED's, a switch and a RC network.

All the main elements are connected to the Expansion Board.

1: Microbit

2: RTC: VCC to 3V, GND to GND, SDA to pin 19 and SCL to pin 20.

3: Mode switch: COM to 3V, T1 to P1 (set enable) and T2 to P8 (display enable)

4: Microbit P2 via a 470R resistor connects to D1 of the first RGB LED.

5: The RGB LED's are supplied by 5V & 0V across which is connected a 1000uF electrolytic capacitior.

These elements are then mounted on a separate sheet of Acrylic which will be attached by screws to the back board.

Power is provided by a USB power adapter with a micro USB terminated cable.

LED Matrix Assembly

The display consists of 100 addressable RGB LED's supplied on a strip.

The strip is cut into lengths of 10 LED's for a total of 10 strips.

Rather than connecting all three wires on each strip serially, I connected the supplies on a loop.

This means from a power perspective the 10 short strips powered at both ends present a parrallel and lower cumulative resistance reducing the effects of volt drops.

The loop is made from 8 x 250(L) x 1.6(dia) mm brass welding rods.

Four rods are cut to a lengths of ~ 18mm and soldered at the corners to form a connected square.

Four rods are cut to shorter lengths of ~ 19mm and soldered at the corners to form a connected square.

These two squares sit in two separate depressions in the outer part of the grid.

Designate each square frame to a supply polarity and mark part of the appropriate frame with coloured varnish/paint, permanent ink or a label.

Cut short lengths of ECW (Enamelled Copper Wire), and connect the supplies of the strips to the corresponding designated supply on the frame.

With a DMM on continuity/low resistance check the connectivity of the strip supply to the wire frame ensuring there are no shorts between the supplies.

Serially connect the DO to DI pins on each strip with ECW.

Connect the pins of three long jumpers to the strip at 5V, 0V and DI close to the corner.

Operation

Before setting the clock ensure that the RTC has a working battery fitted to retain the time when/if power is removed.

The default time setting format is 24 hour mode.

The mode switch (centre off), has two functions time set and Microbit display.

With the switch in the centre position both the set mode and Microbit display are disabled.

In one position, set mode is enabled and the Microbit display is enabled during setting.

In the second position, set mode is disabled and the Microbit display is enabled for time display.

Being able to blank the Microbit display serves two purposes, 1: to save power, 2: as the Microbit is mounted at the back the Display will not be visible therefore it only needs to be visible when setting and verifiying the time.

Move the mode switch to the set time position a plus symbol will be shown on the display.

Press Button A for Hours. (0 to 23)*

Press Button B for Minutes. (0 to 59)*

*Each press incrementing the number to the maximum value and on the next press resetting to zero.

Press Buttons A & B together to set the time, the entered time values will be displayed.

Move the mode switch from the set position either to the centre or Microbit display enable.

With the mode switch in the centre position the Character Display will update after a short delay.

With the mode switch set for Microbit display enable the Microbit will show the time just before the Character Display updates.

At switch on or after setting.

If the clock has been previously set. after a short delay the time will be shown on the clock face.

The code for the Microbit and other details can be found at Instructables

Know your tools and follow the recommended operational procedures and be sure to wear the appropriate PPE.

No affiliation to any of the suppliers used in this project, feel free to use your preferred suppliers and substitute the elements were appropriate to your own preference or subject to supply.

Links valid at the time of publication.