Tag Archives | Servos

Getting Musical with the Crumble

A Crumble powered instrument that can play a tune? You must be mad!

Don’t worry, we thought we were too, but after having this idea in our head for a long time, we finally bought a glockenspiel to try it out-  and lo and behold our Crumble powered glockenspiel is alive.

Surprisingly, you don’t need many parts to make the instrument work. A glockenspiel with a beater, two servos, some cable ties and a sticky pad or two. We placed it on a spare piece of corriflute so that we could keep the servos and the glockenspiel aligned.

We needed two servos for this. One servo with the “cross” attachment, and the other with the “double arm”. These were then wired into the Crumble, one on A and the other on B.

The two servos were then connected with sticky pads and cable ties. The bottom servo moves along the X axis (left to right), and the top servo along the Y axis (up and down).

To allow us to easily play the given notes, we created a variable for each one and worked out, through trial and error, which notes were at which angle.

We then moved onto setting out variables for a crotchet, a minim, and then the angles at which the top servo needs to be to hit the glockenspiel, and where it should rest at.

This is the block of code to hit the ‘F’ key, for one crotchet (same as the beat). The total of the wait statements is 750 milliseconds, which equals 80bpm.

And there you have it, one Crumble-powered Glockenspiel! Our instrument came with some free music, so we decided to use one of those pieces. After piecing together many snippets of code, here is Beethoven’s 9th Symphony – well the first line, in all of its Crumble-y glory.

Crafty Crumble Creations: When Santa got stuck up the chimney!

This year our Crumble Christmas decoration uses a servo to control an “animatronic” Santa leg stuck in a chimney decorated with twinkling lights.

https://vine.co/v/iAO7VBbnQHK

We used:

  • 1 laptop with Crumble software installed
  • Crumble controller; a flexible strip of 30 Sparkle LEDs and a micro Servo (both with crumblisers attached)
  • 1 Crumble-friendly battery box; 3 AA batteries
  • Croc-leads and a micro-USB cable
  • Cardboard blocks, cotton wool balls, cardboard; red and black paint; sellotape & PVA glue

Making the Chimney

The Chimney is made from some sturdy, red cardboard building blocks, that we already had at home, with cotton wool balls stuck on for the “snow”. Santa’s leg is cut out from a cardboard box, painted red and black, with more cotton wool balls as a fur trim. The turning part of the servo is sellotaped onto the back of the leg (excuse the Stormtroooper: we used the box from a Star Wars toy) and the body of the servo is taped onto a smaller yellow block that sits behind and inside the chimney. The Crumble and battery box also rest inside. IMG_9899IMG_9900IMG_9885  

Connecting the Crumble

The Crumble was connected to the battery box with croc-leads and to the computer, using the USB lead. The micro-servo has three connections: power (“+”, “-“) and “control” (labelled “S” on the crumbliser). The power pads were connected to the second set of pads on the battery box and “S” was connected to the Crumble’s pad “C”. The Sparkle strip was connected to “+”,”-“, and “D” on the right-hand side of the Crumble and then wrapped around the base of the chimney. IMG_9897

Programming the Crumble

The servo control block needs to tell the Crumble which output the servo is connected to (in this case “C”) and the angle to set the servo. As this is an absolute, rather than a relative number, we had to do a bit of experimenting. Eventually, we determined that the servo needed to move between 65 and 85 degrees. To slow down the transition, we used a loop which steps the servo 1 degree every 60 milliseconds and a variable “x”, which alternates between 1 and -1, to make it move back and forth. Screen Shot 2015-12-15 at 18.19.04We wanted the Sparkle strip to change colour at the same time as the servo is moving. As there are 20 steps in the loop to move the servo, the simplest way to do this was to use only 20 of the Sparkles. We defined a variable “sprk” to be the index number of the Sparkle. Every time the loop is executed, Sparkles 5 to 25 are set to red, in turn. Variable “x” is used to set the adjacent Sparkle to green. Once we were happy with the effect, we disconnected the Crumble from the computer and placed our decoration on the fireplace. Screen Shot 2015-12-24 at 12.38.51 Can you improve on this and work out how to thread two programs together to use all 30 Sparkles? Merry Christmas!!