115 lines
3.3 KiB
Markdown
115 lines
3.3 KiB
Markdown
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# Accelerometer Beat control
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### @description micro:bit guitar: using accelerometer to control tempo
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### ~avatar avatar
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Use the Accelerometer to control guitar tempo
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* Duration: 30 - 45 minutes
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* Concepts:
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* Gravity
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* Acceleration
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* X, Y, Z coordinates
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* Tempo
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* Beat
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* Mapping
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* Graphing
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* Absolute value
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### ~
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*accelerometer controlled tempo*
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https://youtu.be/h_gPkBaVkoo
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TODO: add sound to video
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## Blocks
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```cards
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input.acceleration(Dimension.Y)
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music.setTempo(120)
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pins.map(0, 0, 1023,60, 320)
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Math.abs(1)
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```
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## Accelerometer, gravity and tilting!
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The micro:bit contains an **accelerometer** sensor that is able to measure forces applied to the board.
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On earth, we are subject to the **gravity force** which pulls us to the ground!
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https://youtu.be/0SULoTKmkhI
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When the micro:bit is flat on a table, with the screen pointing up, the gravity force is aligned
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with the **Z** axis of the micro:bit.
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If you tilt it up and down, the force will align with the **Y** axis -- this is how we can detect tilting!!!
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If the force along **Y** grows, the micro:bit is tilting more and more vertically!
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## Measuring Acceleration along different coordinates (X, Y, Z axis)
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The acceleration block approximately measures **milli-g**, which is 1/1000 of a **g** or the
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acceleration of gravity.
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### Step 1: Graphing acceleration
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```blocks
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basic.forever(() => {
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led.plotBarGraph(input.acceleration(Dimension.Y), 1023)
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})
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```
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**Create the code** that measures the change in the Y axis acceleration as a graph on the LEDs
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**Dowload the code** to the micro:bit
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**Test the movements that move the graph from 1 to 5 bars on the LEDs**
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### Extra
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Try graphing the acceleration along the **X** and **Z** axis. Can you explain the differences?
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### ~hint
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## Mapping
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**It is common to map one standard to another - such as with temperature**
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### ~
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### Step 2: Mapping acceleration to Beat
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**micro:bit sensors produce signal values between 0 to 1023. The *[map block](/reference/pins/map)* converts the signal to a desired range.**
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```blocks
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basic.forever(() => {
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music.setTempo(pins.map(Math.abs(input.acceleration(Dimension.Y)),
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0, 1023,
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60, 320))
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music.playTone(Note.C, music.beat(BeatFraction.Quarter));
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})
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```
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**Create the code** that *Maps* Y axis acceleration as *tempo*
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**Download the code** to the micro:bit on the guitar
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**Test the movements that speed and slow the tempo**
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### Step 3: Combine with light sensor tone control
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**Put it all together!**
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```blocks
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basic.forever(() => {
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music.setTempo(pins.map(Math.abs(input.acceleration(Dimension.Y)),
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0, 1023,
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60, 320))
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music.playTone(
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input.lightLevel() * 25,
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music.beat(BeatFraction.Quarter)
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);
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})
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```
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**Combine the code above with the light sensor tone control code from the previous activity**
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**Download the code** to the micro:bit on the guitar
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### Now play the guitar adjusting tone and tempo using the light sensor and accelerometer!
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### ~button /projects/guitar/pinpress
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NEXT: Pin Press on/off
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### ~
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