…which I have given up making. I just don’t have the skills and resources to make a (polished) webinar like them ‘Youtubers’. So I will stick to what I do best; write.
The main aim of this article is for teachers to get familiarized using a servo with the Microbit and create a lesson plan around it. For an intro to a Microbit, please watch the video which is only a couple of mins long. My background is in using embedded electronics to teach Science and Technology. Of late, my role as Outreach Coordinator in Engineering and CS has allowed me to interact and use a wide range of these nifty devices, Microbit being one of them. Previously it has mainly been the Arduino and Raspberry Pi.
Now if you haven’t heard about any of these, don’t worry. We will start with the Microbit. If you have watched the video by now, I guess you get an idea of its capabilities. But the best part would be to create interactive artefacts to tell a story, which is the outcome of this article.
Why Interdisciplinary activities?
The NZ curriculum has guidelines on how Digital Technology needs to be delivered as a subject area, which is through an integrated approach until it’s taught as a separate subject. This allows teachers to give a context, let’s say a genuine problem that their community is facing, and that something technology can possibly fix. I have used the Microbit mainly with Science (think Climate change, environment monitoring, motion and acceleration, etc.) However, there is nothing stopping someone to make a lesson plan in History (Interactive world war story) or Geography (Inclinometer to measure height of a mountain) or even Physical Education (Step counter, Health monitor).
The important thing is to make a plan, have an outcome in mind as you will have deadlines to meet, so that the end of the project could be a ‘show and tell’.
What is a servo?
It’s a DC (direct current) motor like the ones you have come across in toy cars, except that they have a gear mechanism and some regulators inside. That’s probably the most basic definition, but I am sure you can watch some YouTube videos to get detailed information. Servos can be 180 or 360 degrees rotational. The most common one we will use in the classroom are micro servos (SG90) or you could choose one with metal gears inside (MG90). They rotate 180 degrees. Servos cost around $8 upwards depending on where you buy them from and the type (Analog, Digital, Rotational, Linear etc.)
To drive either servos or motors you need a driver shield (Additional printed circuit board) and driver library. A shield provides the extra power through a battery pack, allowing multiple servo connections at once. It also regulates the current through capacitors and transistors giving constant flow of current as required on demand. The driver library is the (hidden) bit of code that interfaces the hardware with the software. Thanks to clever people who make those files for us ready to use, we just have to import the library into the program. Each shield usually has a related library.
On a side note, you could do without a shield if you are electronics minded. Circuit design is a valuable lesson in electronics and you can get your servo moving saving you lots of dollars for a large class. There are youtube lessons for this.
To get started you will need a Microbit, a servo shield (like this one) and a couple of servos (like this one), a battery pack (4.5v or 6v so either a 3pack or 4pack of AA batteries to go with) and some connector cables.
Instructions for connection and code
- Connect the servos to the connector ports on the shield (0,1,2 on the above shield).
- Connect battery pack to the servo shield
- Use alligator clips to connect microbit and servo shield. 3 cables needed for 3 servos. One each connecting the 0 , 1 and 2 connectors between shield and microbit.
- Open up makecode.microbit.org Go to extensions (at the bottom in the code section).
- Add the servo shield by searching for ” servo “. It’s usually the first one that shows up.
- Depending on what you want to make your servo do, you will need to add appropriate code.
Below is a short time lapse video of the actual workshop I hosted in my learning lab. It’s edited and it just shows some highlights of the session.
Troubleshooting
If your servo is not spinning yet, try one of these:
- Check if your servo is wired up correctly, brown is ground and goes into the negative marked pin on the servo shield.
- Is your Servo shield powered and the right way round? Red is positive, Black is ground usually on the power packs. The light will come on the board if it’s going.
- Is your Microbit powered?
- Is there an error code on the Microbit? Go to the troubleshooting page for Microbit to check what the error code means.
- Update firmware if you have an older Microbit. Ensure the firmware matches the version.
Now the fun part. You have your servo going. Look up some really cool projects made on Twitter at #microbitVirtualConcert and if you are going to make this project use #servoswithacause
I wanted to make this project in a shoebox as it showcases a diorama in a small space which I think is cool while emphasizing the important aspect of recycling material whenever possible. For the next part, I sifted through the material in magazines mainly National Geographic and Nature thereby limiting my theme to nature, wildlife and climate change. Students can bring a variety which provides more options such as Time magazine and the Listener.
Once you have cut out material you want, arrange it in your shoebox. When happy with the layout, and you know what you are going to be ‘moving’, start gluing them in. Remember that you are trying to tell a story using the servos.
Linear motion
Now you can buy linear rotational servos and motors, but they cost more money. While working on this project at home I came across one of my kids’ toy which I decided to use (steal) for this project. All for a good cause eh!
It isn’t too hard to make linear movement, but you will need more time and it could be a good challenge for that student who wants to push themselves in areas of design (3D printing) and development.
So finally, the project all comes together in a nice little box. Unfortunately, my wife wouldn’t part with any of her shoeboxes so I have a laptop box. It worked out well in the end as I have space to pop the electronics in as well. On the shoebox I would just use Bluetack it to the back or top.
Please feel free to leave a comment or ask questions.