CH23-D - NeoPixel Rainbow Steps

The magical thing about these “Individually Addressable” LEDs is that you don’t have to connect each LED to an individual pin on your micro:bit, you just need one signal wire along with power (Positive and Negative) to light things up.

So let's get connected! If you turn the NeoPixel Strip over you'll see labels for the three pins. You should see IN, VCC, and GND.

Use the Crazy Circuits Ribbon Cable to connect the NeoPixel Strip to the Bit Board.

The end with S1, +, and - can plug directly into the Pin 13 row (make sure S1 goes into 13) and the other end should plug into the NeoPixel Strip as shown.

We only need three wires for the NeoPixel Strip so you can leave S2 (the Orange wire) unconnected.

We'll also connect a potentiometer using Maker Tape. Connect it to GND, Pin 0, and 3V. (The center hole connects to Pin 0.)

To mount the NeoPixel Stick in place we used our NeoPixel Beam Holder with a long Technic Beam and two 1x1 LEGO bricks.

You can always use rubber bands, tape, or some other method.

The important thing is to make sure the connector is on the left hand side so the number index for the NeoPixel strip makes sense.

If you've never used a micro:bit before you'll want to check out this guide: Bit Board V2 Setup and Use

We're going to load the following code for our NeoPixel Rainbow Steps program: https://makecode.microbit.org/_PXP3pzcsd...

We'll once again map the input from the potentiometer to a smaller scale. While the input will be from 0 to 1023 our output will be from 0 to 8. This effectively turns the potentiometer into a multi-position switch.

We will rotate the lit up pixels (using the show rainbow function) anywhere from 0 to 8 steps.

Once the code is loaded it should start running immediately.

You can power the micro:bit via the USB cable you used to load the code or you can use a battery pack plugged into the Bit Board.

With the potentiometer turned all the way anti-clockwise you'll see that the pixels do not move.

If you rotate the potentiometer all the way clockwise it will also appear that the pixels are not moving... But! They are moving, just 8 steps at a time, which means they appear to not be moving.

With the potentiometer all the way anti-clockwise start to turn the potentiometer slowly in the clockwise direction and you'll see the pixels move. First one step, then two, then three, etc...

When you get past the halfway point on the potentiometer the pixels may appear to start moving backwards, but they are not!

If the pixels appear to be moving backwards what we are seeing is sometimes call the Wagon-wheel effect which is usually related to film frames and rotating objects.

Follow along with our recorded Live Stream!

You can watch the full video of us walking through this project, along with explaining and exploring the code: https://www.youtube.com/live/-2ECPBjKX1Q