116 lines
3.3 KiB
Markdown
116 lines
3.3 KiB
Markdown
# Accelerometer Beat control
|
|
|
|
### @description micro:bit guitar: using accelerometer to control tempo
|
|
|
|
### ~avatar avatar
|
|
|
|
Use the Accelerometer to control guitar tempo
|
|
* Concepts:
|
|
* Gravity
|
|
* Acceleration
|
|
* X, Y, Z coordinates
|
|
* Tempo
|
|
* Beat
|
|
* Mapping
|
|
* Graphing
|
|
* Absolute value
|
|
|
|
### ~
|
|
|
|
## Duration: 30 - 45 minutes
|
|
|
|
*accelerometer controlled tempo*
|
|
https://youtu.be/kA0HpqCWsjs
|
|
|
|
## Blocks
|
|
|
|
```cards
|
|
input.acceleration(Dimension.Y)
|
|
music.setTempo(120)
|
|
pins.map(0, 0, 1023,60, 320)
|
|
Math.abs(1)
|
|
```
|
|
|
|
## Accelerometer, gravity and tilting!
|
|
|
|
The micro:bit contains an **accelerometer** sensor that is able to measure forces applied to the board.
|
|
On earth, we are subject to the **gravity force** which pulls us to the ground!
|
|
|
|
https://youtu.be/0SULoTKmkhI
|
|
|
|
When the micro:bit is flat on a table, with the screen pointing up, the gravity force is aligned
|
|
with the **Z** axis of the micro:bit.
|
|
|
|
|
|
|
|
If you tilt it up and down, the force will align with the **Y** axis -- this is how we can detect tilting!!!
|
|
If the force along **Y** grows, the micro:bit is tilting more and more vertically!
|
|
|
|
## Measuring Acceleration along different coordinates (X, Y, Z axis)
|
|
|
|
The acceleration block approximately measures **milli-g**, which is 1/1000 of a **g** or the
|
|
acceleration of gravity.
|
|
|
|
### Step 1: Graphing acceleration
|
|
```blocks
|
|
basic.forever(() => {
|
|
led.plotBarGraph(input.acceleration(Dimension.Y), 1023)
|
|
})
|
|
```
|
|
**Create the code** that measures the change in the Y axis acceleration as a graph on the LEDs
|
|
|
|
**Dowload the code** to the micro:bit
|
|
|
|
**Test the movements that move the graph from 1 to 5 bars on the LEDs**
|
|
|
|
### Extra
|
|
|
|
Try graphing the acceleration along the **X** and **Z** axis. Can you explain the differences?
|
|
|
|
### ~hint
|
|
## Mapping
|
|
**It is common to map one standard to another - such as with temperature**
|
|
|
|
### ~
|
|
|
|
### Step 2: Mapping acceleration to Beat
|
|
**micro:bit sensors produce signal values between 0 to 1023. The *[map block](/reference/pins/map)* converts the signal to a desired range.**
|
|
```blocks
|
|
basic.forever(() => {
|
|
music.setTempo(pins.map(Math.abs(input.acceleration(Dimension.Y)),
|
|
0, 1023,
|
|
60, 320))
|
|
music.playTone(Note.C, music.beat(BeatFraction.Quarter));
|
|
})
|
|
```
|
|
|
|
**Create the code** that *Maps* Y axis acceleration as *tempo*
|
|
|
|
**Download the code** to the micro:bit on the guitar
|
|
|
|
**Test the movements that speed and slow the tempo**
|
|
|
|
### Step 3: Combine with light sensor tone control
|
|
**Put it all together!**
|
|
|
|
```blocks
|
|
basic.forever(() => {
|
|
music.setTempo(pins.map(Math.abs(input.acceleration(Dimension.Y)),
|
|
0, 1023,
|
|
60, 320))
|
|
music.playTone(
|
|
input.lightLevel() * 25,
|
|
music.beat(BeatFraction.Quarter)
|
|
);
|
|
})
|
|
```
|
|
**Combine the code above with the light sensor tone control code from the previous activity**
|
|
|
|
**Download the code** to the micro:bit on the guitar
|
|
|
|
### Now play the guitar adjusting tone and tempo using the light sensor and accelerometer!
|
|
|
|
### ~button /projects/guitar/pinpress
|
|
NEXT: Pin Press on/off
|
|
### ~
|