pxt-calliope/docs/projects/guitar/pinpress.md

Pin Press Switch

@description micro:bit guitar: use pin press to toggle guitar play on/off

~avatar avatar

Use pin press to switch guitar play on/off

• Duration: approximately 45 minutes
• Materials:
  • 2-3 Crocodile clips
• Concepts:
  • Circuit
  • Conductor
  • Variable/Global-Variable
  • Conditional: if, else
  • Boolean: True/False

~

Blocks

var on = false
on;
if (on) { } else {}
input.onPinPressed(TouchPin.P1, () => {})

~hint

Circuits & Switches

• Circuits need a power supply (battery), a resister (like a LED) & a conductor (metal, water, hand)
• Switches turn electric power on by closing (completing) a circuit with a conductor so power can flow

Metal foil and wires make excellent conductors

In this activity we use YOU to conduct electricity
to close the circuit that switches the guitar ON and OFF!

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Step 1: Pin Press Test

input.onPinPressed(TouchPin.P0, () => {
    basic.showNumber(0)
})
input.onPinPressed(TouchPin.P1, () => {
    basic.showNumber(1)
})
input.onPinPressed(TouchPin.P2, () => {
    basic.showNumber(2)
})

Create the pin-press code

Download the code on the micro:bit

https://youtu.be/PAIU-vHqyGU

Hold the micro:bit touching The GND pin with one hand
with the other hand alternately touch the 0, 1 and 2 pins

~hint

The electric signal traveled from pins, between your hands to GND and the micro:bit detected the electric signal!

~

Step 2: Installing conductive foil on the guitar

https://youtu.be/NX0ECcpXFes
Add foil to the guitar body where it is easy to touch while playing

Connect the foil to GND using a crocodile clip

https://youtu.be/YkymZGNmkrE
Add foil to the guitar neck

Connect the foil to pin 1 using a crocodile clip

Step 3: Add a switch to turn the guitar ON and OFF

Using the on global variable we can switch the message on the micro:bit
between ON and OFF

let on = false
basic.forever(() => {
    if (on == true) {
        basic.showString("ON")
    } else {
        basic.showString("OFF")
    }
})
input.onPinPressed(TouchPin.P1, () => {
    if (on == true) {
        on = false
    } else {
        on = true
    }
})

Create the ON/OFF switch code

Download the code on the micro:bit

Test by touching P1 to toggle the LED message between ON and OFF

Final code TODO: do we want to use on = !on; or be more direct in flipping the switch? on = true; on = false;

var on = false
basic.forever(() => {
    if (on) {
        music.setTempo(pins.map(Math.abs(input.acceleration(Dimension.Y)),
            0, 1023,
            60, 320))
        music.playTone(
            input.lightLevel() * 25,
            music.beat(BeatFraction.Quarter)
        );
    } else {
        music.rest(music.beat())
    }
})
input.onPinPressed(TouchPin.P1, () => {
    on = !on;
})

Now Play!

Turn the guitar ON and OFF with a pin press on the connected foil
touching both pieces of foil at the same time to connect the switches

https://youtu.be/GYmdTFvxz80