CH34-D - Distance Sensor Pixels

We'll connect the Distance Sensor with a Crazy Circuits Ribbon Cable using all four wires.

Plug the three-wire connector of the Crazy Circuits Ribbon Cable into the row with Pin 13 on the Bit Board. The wire colors should match the pin header colors, with S1 (yellow) going to the yellow pin.

Next, plug S2 (orange) into Pin 14. (S2 is separated from the three-wire connector to allow you to plug it into another row.)

Plug + (red) into VCC; S2 (orange) into TRIG; S1 (yellow) into ECHO; and - (black) into GND.

We used a 3D printed part we designed to hold the Distance Sensor in place on the LEGO baseplate.

A few Technic pins, a Technic beam, and a some LEGO bricks are all that is needed.

Alternately you can use some LEGO bricks and a rubber band or tape to hold the sensor in place. (But don't use anything conductive!)

3D print your own Distance Sensor Holder with Holes. (It's the same one we use in our Bit Boar Rover Kit).

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 Distance Sensor Pixels program: https://makecode.microbit.org/_ihJLfKJLk...

In the forever block we'll set Pin 14 and Pin 13 to TRIG and ECHO (respectively) so we can read the Distance Sensor. This allows us to continually read the sensor and assign the value to distance.

The forever block looks pretty simple, and that's because all of the heavy lifting is done in the plotter function.

The plotter function takes a single number between 1 and 25 and then gets the values to plot it on the X/Y grid of LEDs.

We'll first number our LEDs from 1 to 25 and look at how that maps out to our X axis (0 through 4) and our Y axis (0 through 4).

The Y value is easy. When we pass 13 to our function we divide by 5 (which is the number of LED rows) and get 2.6. If we then floor that value (which means to "round down") we get 2. (13 is in row number 2.)

The X value is a little more complicated, but you can work through it just like any calculation, starting from the innermost parenthesis working outward.

The decimal part of the 2.6 gives us the 6 which eventually becomes 3 and you can see that 13 is in column 3 of the LED matrix.

The code for this was a bit complex and we ended up writing it in Python outside of MakeCode and then implemented it using the blocks available... and it works!

We copied the text from the Python mode of MakeCode to create the diagrams for this step. If you are familiar with Python (or JavaScript!) remember that you can always switch the mode in MakeCode.

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.

Move your hand (or a flat object) in front of the sensor. As you get closer you'll see the LED matrix react by moving the lit LED corresponding from 1 to 25.

Follow along with our recorded Live Stream!

(We'll add the video to this step after we do the stream!)