7

Colour-sensing clutch with Circuit Playground Express

SCHOOL OF MAKING

Variables menu. Drag the ‘Set strip to 0’ block into the

On Start loop.

Click on the Light menu to reveal the nested

NeoPixel menu. Click on NeoPixel to view more

options for strips. Find the round module labelled

‘Create strip on A1 with 24 pixels’ and drag it onto

the workspace. Drop it onto the ‘Set strip to 0’ block,

directly on top of the ‘0’. From now on in our code,

the variable ‘strip’ is the placeholder for the NeoPixel

strip we have connected to pin A1. Change the

number 24 to the actual number of LEDs on your strip

(ours was 12).

One other setup item we need to address is setting

the thresholds for the light sensor. Depending on

the amount of light in your environment, you may

need to experiment with these settings to get a good

reading from the light sensor. Even if yours works

great right from the start, it’s good to know where

these settings are, because chances are you’ll need

to tweak them eventually.

The light sensor is an input, so head into the Input

menu and scroll down to find the ‘Set dark threshold

value to 0’ block. Drag this block into the On Start

loop, and just leave the value at 0 for now. Duplicate

the block by right-clicking and selecting ‘duplicate’.

Drag the new block into place right underneath

the first one, and click on the drop-down menu to

change ‘dark’ to ‘bright’. Leave this one at 0 for

now also. Later on, if you’ve downloaded the code

to your Circuit Playground Express and the sensor

doesn’t seem to be responding correctly, you can

adjust these threshold values until the sensor works

well in your particular lighting conditions.

MAKE A STARTUP SEQUENCE

Now let’s create a startup sequence so that we

know the lights are working when we turn on the

Circuit Playground Express. Head into the Light

menu and grab the ‘Show rainbow animation

for 500 ms’ block. Add it to the On Start block,

and click on the drop-down menu to change the

duration from 500 ms to 1 second. In the Circuit

Playground Express simulator, you’ll see that we

just programmed the on-board NeoPixels to show

a rainbow animation. Let’s also make the NeoPixel

strip on pin A1 show the same animation.

Click on the Light menu again to get to the

NeoPixel menu, and find the ‘strip show rainbow

animation for 500 ms’ block. Drag it into the On Start

loop under the previous animation, and change the

duration to 1 second. Although you won’t see it in

the simulator, our NeoPixel strip will now show the

same animation as the on-board NeoPixels.

Depending on the amount of light in your environment,

you may need to experiment with these settings to get

a good reading from the light sensor

”

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Right

Match your clutch

bag with clothes

or accessories