- 5x BBC micro:bit.
- 4x ZIP HALO with ZIP Circle extensions.
- Klimate environment sensor board.
- Motor driver board.
- Stacking pin headers.
- 3mm MDF.
- 5V Solenoid.
- Our design files.
- A desk bell we found in the office (as you do).
Klimate, microbit and ZIP Halo Big Ben - BETT 2019 Part 3:Designing this building brought up some interesting decisions. It needed to be sturdy for such a large model, yet keep the details that make Big Ben so recognisable. To solve this, the more detailed “head” of the model is removable; while the tower is a simpler finger jointed construction using the paper cladding more for its detail. Here the model has been made transparent so you can see how the clockfaces fit together. You can also see the parts on the left from where the first version of the model had a pointed roof.
Building Big BenAssembling the tower was relatively simple. First, we laser cut all of the MDF panels (you can download the DXF files here). The tower section uses finger jointed corners hot glued together the same way as in our previous guide. The two sections friction fit together thanks to the hot glue we used in the corners The clock face is much more complex to put together. We started with the base piece, glued on the four panels that form the connector, then worked upwards. There are two layers to the clock face. The inner layer holds the ZIP Halo, and the outer one is decorative. Both use butt joints in an anticlockwise direction. An important step was to test fit both layers with the Halo to make sure they had the correct orientation. Finally, we glued the inner layers to the base piece, followed by the outer. We made use of the ZIP Halo board's extension pads to link a ZIP Circle, making a chain of 36 ZIP LEDs in total. The circle is attached to a mount (we made ours from 2mm perspex) which screws straight to the mounting holes of the Halo. Applying the artwork to the sides was a simple but delicate step. High-quality print settings and cutting the sheets with a craft knife gave the best results. Two sheets on the tower body overlap in the middle, meaning a total of eight are needed. We used broad double sided tape but a glue stick may be a little more forgiving if the artwork isn’t quite lined up.
Note: A neat trick for the best fit is to cut the sheet roughly to size with some white left on the sides. Stick this to the panel then cut the remainder to size using the edge of the MDF as a ruler!
The ElectronicsThis model does a lot to run the rest of the Kitronik :CITY layout and the key to this is the Klimate environment sensor and Real Time Clock (RTC) board (also available as the RTC alone). This board keeps exact time in hours, minutes and seconds and measures climate conditions; then sends commands and information to every other model on the layout. You may have noticed a second board under the Klimate & RTC board above. This is our trusty motor driver making use of our new stacking pin headers, meaning two different boards can be run from a single microbit! The motor driver is powering a 5V solenoid. Solenoids are linear motors, meaning rather than spinning when current passes through them, they push forward or back. We added this after finishing Big Ben because what would it be without a bell! We designed a frame to hold a desk bell inside the clock face with the solenoid set to push the button and ring the bell.
The Code:The custom blocks downloadable for this board make accurate timing in your projects much simpler. To find these in Microsoft MakeCode open the “Advanced” dropdown menu, select “Extensions” then search Kitronik. The microbit on top is coded to broadcast commands to the rest of the city via the radio function. It also sends temperature data to be shown on the display of Picadilly Circus. To set the time you will need to use the “Set Time To [ ] Hrs [ ] Mins [ ] Secs” block. Build a simple code to set the time on start, then start it a few minutes in advance of the time you entered. When the time you entered arrives, reset the microbit to synchronise the board with the real time. If you use a coin cell in the board’s CR2032 coin cell holder, you will only have to do this once since this keeps the time even when the board has no power. You can now delete the time setting code (Keep a copy for if the battery ever runs out) and write your new code to use the board’s time with the “Read as number” blocks.
Kitronik :CITY Resources:Our Kitronik :CITY stand attracted a lot of attention at BETT 2019. Many of our visitors also expressed a desire to make something similar once they returned to their schools. We decided to help out by producing the guides below. Each part of the :CITY has its own guide and each guide has all of the files, code and also instructions included. Additionally, if you or your students tackle any of the builds below then we would love to see the pictures. With your permission, we would also like to feature them in the Gallery (Gallery@kitronik.co.uk).
|Make A microbit Controlled Kitronik :CITY:|
|Kitronik :CITY Part 1 - Laser Cut :MOVE Mini Garage.|
|Kitronik :CITY Part 2 - :MOVE Mini Football Stadium.|
|Kitronik :CITY Part 3 - Klimate, microbit & ZIP Halo Big Ben.|
|Kitronik :CITY Part 4 - Servo Driver Board Tower Bridge.|
|Kitronik :CITY Part 5 - Robotics Board London Eye & Turbine.|
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