What’s a Crumble?
There are an increasing number of microcomputers from the Arduino boards to the Raspberry Pi. The Arduino and Crumble share many similarities. They are incredibly basic and need another computer to create programs on before transferring the compiled program to the Arduino or Crumble for it to run.
I had already used MicroBits in schools (see my earlier post). They are similar to the Crumble in that you need to use another computer to create your program before uploading it to the MicroBit. The MicroBit, however, is a more complex beast with an array of lights for communication and a range of sensors from temperature, to tilt and a compass. The MicroBit also allows you to connect to a tablet or another MicroBit using Bluetooth radio too.
Where the Crumble has its niche is that it has large connector surfaces (pads) designed to be used to wrap wire around or to use a crocodile clip to make a quick connection. This, and the fact it is so robust, makes it an excellent choice for a maker project for younger children.
The Crumble has a growing range of things you can connect to it. The programming language is free to download and runs on Windows, Mac and Linux (I’ve tried all three) and will be familiar in format to anyone who’s ever programmed Scratch and so quick and easy to pick up! It’s also really easy to transfer your program from the software to your physical Crumble.
The Crumble IS basic. You can connect a variety of things to its four input/output pads AND connect up to two motors to its dedicated motors pads. The Crumble has resistors built in which means you can connect switches, sensors, LEDs and motors without risk of weird things happening, or risk to the Crumble itself.
One of the funkiest things to start with are what’s called ‘Sparkles‘. These are addressable LEDs . Basically you plug in a number of sparkles ‘daisy-chained‘ together in a line and then you can program the Crumble to set each Sparkle to a specific colour and intensity of light individually. You could create your very own coat of many colours, and colours which change too!
This project was centred on the use of Motors however. The challenge for the pupils (or in may case Cubs at winter camp) was to create and program a vehicle using 2 motors, some crocodile clips, a Crumble and a battery pack and a load of junk modelling (oh and a laptop for the programming part).
We laid out a course on a hard-surfaced floor using masking tape and then we got down to the kind of movement we were looking for.
Movement and Steering
We talked about how a TANK moves and looked at some pictures and some video from YouTube. We noticed that the tank doesn’t have wheels (like cars and vans) which turn at the front when the tank steers. So I picked two volunteers and gave them a broom! I got them to stand next to each other holding the broom across them in front with both hands on the broom. If they BOTH move forward they manage to move roughly straight BUT how about a turn. They quickly work out one person can stop and the other person moves and they turn. With a little prompting you can get one person to go backwards and the other to go forwards and they spot a tighter turn, in fact on the spot. Why do this? Because our crumble can control two motors. We COULD devise a very complicated model with front axle which pivots and employ a stepper motor or servo to turn the front wheels BUT the best idea is to create their Crumble vehicle like a tank!
Making our vehicle
Our vehicles were only ever intended to be temporary. The whole thing was held together with masking tape so that we could photograph and disassemble for the next group. You might be lucky enough to be able to create something MUCH more permanent if you can afford to buy lots of motors and wheels in which case a glue-gun would be a real boon! So the kids set to work creating their model. We had false starts. It’s amazing how kids can be blinded by a glossy container and then find they attach their motors and wheels only to find that the wheels don’t touch the ground but they all got there in the end! As I say ours were basic because time was very short!
Once they had something stable then it was the trial and error bit. When you do this have a START box clearly marked so their model can be positioned in exactly the same space each time they test their program. Our course started with a long straight. This gave them time to try a program which started both motors and waited for a bit. This program is a disaster because the Crumble does exactly what you program it to do. Start motor and wait for a bit is great but the motor will keep going until you tell it to STOP!
Eventually they work out how to get their vehicle to the first turn. Then the real fun starts. How do we make it turn?
We had a few models with wheels which were not mounted very parallel to each other. On the whole it wasn’t the end of the world BUT, through trial-and-error we realised, it was easier for the kids to program if they lowered the speed of the motor on the side which their vehicle was turning FROM until their vehicle could go in a straight line again!
There is always a group which struggles to work out that if their motors are mounted in opposite directions one of them HAS to go in reverse for their model to go straight otherwise it just goes around in circles!
We ran out of time. My test group were Cubs on camp and we had only one hour to do all of this in… They did really well, but in the end it was the group that went furthest that ‘won’. You could put them against the clock if lots of your groups complete the course, or you could devise a more fiendish course as the next stage!
We had hoped to have time to add a Sparkle Light to create emergency or rescue vehicles with programmed flashing lights and decorated bodies for their vehicles but time…