Coding the Guitar

Step 1: Make an animation using the Motion Sensor

The motion sensor measures acceleration along 3 dimensions:

• X-axis (left and right)
• Y-axis (forward and backward)
• Z-axis (up and down)

It uses values from -1023 to 1023. When the Adafruit Circuit Playground Express is laying flat, face up: X = 0, Y = 0, Z = -1023

Open MakeCode in your web browser.

Go into the Light toolbox drawer, and click on the More subcategory. Drag the ||light:graph|| block onto your programming workspace, and put it in the ||loops:forever|| loop.

forever(() => {
    light.graph(
    0,
    0
    )
})

Now, in the Input toolbox drawer, drag the ||input:acceleration|| block into the first slot of the ||light:graph|| block.

forever(() => {
    light.graph(
    input.acceleration(Dimension.X),
    0
    )
})

Using the drop-down menu on the ||input:acceleration|| block, change to the y axis. Set the maximum value to 1023 by typing this number into the second slot of the ||light:graph|| block.

forever(() => {
    light.graph(
    input.acceleration(Dimension.Y),
    1023
    )
})

Step 2: Add Music

Open the Loops toolbox drawer, drag a ||loops:forever|| block onto the programming workspace.

In the Music toolbox drawer, drag the ||music:play tone|| block into the ||loops:forever|| loop.

forever(() => {
    music.playTone(262, music.beat(BeatFraction.Half))
})

Now we want to change the pitch, or the note that’s being played, based on the light level (darker makes a lower note and brighter makes a higher note).

The Adafruit Circuit Playground Express can play notes that are represented as frequency values (in Hertz). Also, the Adafruit Circuit Playground Express measures how light or dark it is through a light level sensor ( 0 = completely dark and 255 = bright light.).

We want to map the light level values (0 - 255) to frequency values. 300 MHz is about the frequency for the Middle D note, so let’s add 300 to our light level values.

Open the Math toolbox drawer, drag the ||math:addition|| block into the first slot of our ||music:play tone|| block.
Then Open the Input toolbox drawer, drag the ||light level|| block into the the first value of our ||math:addition|| block, and type the value 300 into the second value.

forever(() => {
    music.playTone(input.lightLevel() + 300, music.beat(BeatFraction.Half))
})

Now let’s change the tempo based on the motion of our guitar. The motion sensor measures acceleration along 3 directions: X-axis (left and right), Y-axis (forward and backward), and the Z-axis (up and down).

Acceleration uses values from -1023 to 1023. The tempo is the number of milliseconds that the tone lasts for, and these values are always positive (1000 milliseconds = 1 second).

Go to the Math toolbox drawer, drag ||math:absolute|| value block into the second slot of our ||music:play tone|| block.

Open the Input toolbox drawer, drag the ||input:acceleration|| block into the ||math:absolute|| value block.

forever(function () {
    light.graph(
    input.acceleration(Dimension.Y),
    1023
    )
})
forever(function () {
    music.playTone(input.lightLevel() + 300, Math.abs(input.acceleration(Dimension.Y)))
})

Complete!

Download you code to the Adafruit Circuit Playground Express. Now, it’s time to play your guitar!