pxt-calliope/docs/getting-started.md

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# Getting started
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## ~avatar
Are you ready to build cool BBC micro:bit programs?
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Here are some challenges for you. Arrange the blocks in the editor
to make real programs that work!
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## ~
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### Happy face
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Use the **Basic** drawer in the editor (to the left)
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to drag out and arrange three blocks (two `show leds` and one `forever` block)
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to create this program:
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```blocks
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basic.forever(() => {
basic.showLeds(`
. . . . .
. # . # .
. . . . .
# . . . #
. # # # .
`)
basic.showLeds(`
. . . . .
. . . . .
. . . . .
. . . . .
. . . . .
`)
});
```
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When you run this program (click the **Play** button) you will see a smiley face, then a blank
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screen, then a smiley again -- it never stops! (That's because of the
``forever`` block.)
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Click **Compile** to move your program to the BBC micro:bit!
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### Happy unhappy face
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Draw an unhappy face instead of the blank screen. Click on the dots
in the second ``show leds`` block until it matches the blocks below.
Now you have an **animation** (cartoon) that shows a happy face,
then an unhappy one, then a happy one again, forever (or until
you turn off your micro:bit)!
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```blocks
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basic.forever(() => {
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basic.showLeds(`
. . . . .
. # . # .
. . . . .
# . . . #
. # # # .
`)
basic.showLeds(`
. . . . .
. # . # .
. . . . .
. # # # .
# . . . #
`)
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});
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```
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Click **Compile** to move your program to the BBC micro:bit!
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### Your turn!
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Pile up more ``show leds`` blocks to create an animation! Create an
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animation with at least 5 pictures. What does this animation show?
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```blocks
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basic.forever(() => {
basic.showLeds(`
. . . . .
. # . # .
. . . . .
# . . . #
. # # # .
`)
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basic.showLeds(`
. . . . .
. # . # .
. . . . .
# # # # #
. . . . .
`)
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basic.showLeds(`
. . . . .
. # . # .
. . . . .
. # # # .
# . . . #
`)
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basic.showLeds(`
. . . . .
. # . # .
. . . . .
# # # # #
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. . . # #
`)
basic.showLeds(`
. . . . .
# . # . .
. . . . .
# . . . #
. # # # .
`)
basic.showLeds(`
. . . . .
. . # . #
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. . . . .
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# . . . #
. # # # .
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`)
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});
```
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Click **Compile** to move your program to the BBC micro:bit!
#### ~hint
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You can find the ``show leds`` block in the **Basic** part of the editor.
#### ~
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### Button A and button B
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This program will show the word **ANTEATER** on the LED
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screen when you press button `A`.
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```blocks
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input.onButtonPressed(Button.A, () => {
basic.showString("ANTEATER");
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});
```
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#### ~hint
The ``showString`` block can show letters, numbers, and punctuation
on the micro:bit screen.
#### ~
Now try to unscramble these blocks in the editor so that the micro:bit
shows **BANANA** when you press button `B`.
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```shuffle
input.onButtonPressed(Button.B, () => {
basic.showString("BANANA");
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});
```
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#### ~hint
You can find the letter `B` by clicking the letter `A` on the
``onButtonPressed`` block.
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#### ~
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Click **Compile** to move your program to the BBC micro:bit!
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#### Your turn!
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Can you combine these blocks so your program shows your real name
instead of **ANTEATER** when you press `A`, but _your secret agent
name_ instead of **BANANA** when you press `B`?
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### Shake
You can find when someone is shaking the BBC micro:bit by checking its
**accelerometer** (it finds whether the micro:bit is speeding up or
slowing down).
Unscramble these blocks in the editor to show a frownie when someone
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shakes the micro:bit. (Ouch!)
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```shuffle
input.onGesture(Gesture.Shake, () => {
basic.showLeds(`
. . . . .
. # . # .
. . . . .
. # # # .
# . . . #`);
});
```
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Click **Compile** to move your program to the BBC micro:bit!
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### Pins
You can also use the pins as buttons. (The pins are the holes in the
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metal stripe at the bottom of the micro:bit board.) For example, hold
the ``GND`` button with one hand and touch the ``0`` pin (called
``P0``) with your other hand to tell the micro:bit you're pressing it.
Unscramble the blocks in the editor to show a heart when you touch
pin ``P0``.
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```shuffle
input.onPinPressed(TouchPin.P0, () => {
basic.showLeds(`
. # . # .
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# . # . #
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# . . . #
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. # . # .
. . # . .`);
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});
```
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Click **Compile** to move your program to the BBC micro:bit!
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## ~hint
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Try this experiment: find a friend and hold hands. Touch the ``GND``
pin while your friend presses the ``P0`` pin. You should see the
heart! The electric current is going through your bodies and across
your handshake to make it happen!
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## ~
## The amazing coin flipper
### ~avatar avatar
Are you trying to choose whether to play soccer or go to the movies
instead, or which toppings to have on your pizza? Build a coin
flipping machine with the BBC micro:bit to choose for you!
### ~
Here are the blocks to make your coin flipper. When you press button
`B`, the coin flipper will show either `H` for heads or `T` for tails
on the LED screen.
```blocks
input.onButtonPressed(Button.B, () => {
if (Math.randomBoolean()) {
basic.showString("H");
} else {
basic.showString("T");
}
});
```
### ~hint
The ``pick random true or false`` block randomly tells the ``if``
block `true` or `false`. If the ``pick`` block picked `true`, the
``if`` block shows the letter `H`. Otherwise, it shows the letter `T`.
That's it!
### ~
### Keeping score
#### ~avatar
To keep track out of how many guesses you've won,
add these blocks to your coin flipper:
#### ~
```blocks
input.onButtonPressed(Button.A, () => {
game.addScore(1);
});
input.onButtonPressed(Button.AB, () => {
basic.showNumber(game.score());
});
```
These blocks mean that if you press button `A`, you will add `1` to
your score, and if you press `A` and `B` together, the micro:bit will
show your score.
When you're done, your coin flipping program should look like this:
```blocks
input.onButtonPressed(Button.B, () => {
if (Math.randomBoolean()) {
basic.showString("H");
} else {
basic.showString("T");
}
});
input.onButtonPressed(Button.A, () => {
game.addScore(1);
});
input.onButtonPressed(Button.AB, () => {
basic.showNumber(game.score());
});
```
Flip until your thumbs get tired!
## Let's play Rock Paper Scissors!
### ~avatar avatar
Build a Rock Paper Scissors game with the BBC micro:bit! You can play
the game with a friend who has it on a micro:bit. You can also play
it with friends who are just using their hands. (The game is built
like a coin flipper, but with three choices instead of two.)
### ~
## Step 1: Getting started
We want the micro:bit to choose rock, paper, or scissors when you
shake it. Try creating an ``on shake`` block so when you shake the
micro:bit, it will run part of a program.
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Clear up the blocks and add the blocks below.
```blocks
input.onGesture(Gesture.Shake, () => {
})
```
Next, when you shake the micro:bit, it should pick a random number from `0` to `2`
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and store it in the variable `item`.
Add a ``set`` block with a variable. Then add a ``pick random`` block,
and store the random number in the variable,
like this:
```blocks
input.onGesture(Gesture.Shake, () => {
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let item = Math.random(3)
})
```
### ~hint
No one can predict random numbers. That's what makes them great for Rock Paper Scissors!
### ~
Each possible number these blocks can make (`0`, `1`, or `2`) means a different picture.
We will show the right picture for that number on the LED screen.
## Step 2: Picking paper
Put an ``if`` block after the ``let`` block that checks whether
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`item` is `0`. Make sure the ``if`` block has an ``else if`` part
and an ``else`` part.
Next, add a ``show leds`` block that shows a
picture of a piece of paper:
```blocks
input.onGesture(Gesture.Shake, () => {
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let item = Math.random(3)
if (item == 0) {
basic.showLeds(`
# # # # #
# . . . #
# . . . #
# . . . #
# # # # #
`)
} else if (false) {
} else {
}
})
```
## Step 3: A random rock
Now we are going to add a new picture for the micro:bit to show
when another random number comes up.
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Make the ``else if`` part check if the variable `item` is `1`.
Then add a ``show leds`` block with a picture of a rock.
```blocks
input.onGesture(Gesture.Shake, () => {
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let item = Math.random(3)
if (item == 0) {
basic.showLeds(`
# # # # #
# . . . #
# . . . #
# . . . #
# # # # #
`)
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} else if (item == 1) {
basic.showLeds(`
. . . . .
. # # # .
. # # # .
. # # # .
. . . . .
`)
} else {
}
})
```
## Step 4: Suddenly scissors
Add a ``show leds`` block with a picture of scissors to the ``else`` part:
```blocks
input.onGesture(Gesture.Shake, () => {
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let item = Math.random(3)
if (item == 0) {
basic.showLeds(`
# # # # #
# . . . #
# . . . #
# . . . #
# # # # #
`)
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} else if (item == 1) {
basic.showLeds(`
. . . . .
. # # # .
. # # # .
. # # # .
. . . . .
`)
} else {
basic.showLeds(`
# # . . #
# # . # .
. . # . .
# # . # .
# # . . #
`)
}
})
```
### ~hint
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You don't need to check if `item` is `2` because `2` is the only number left out of `0`, `1`, and `2`.
That's why you can use an ``else`` instead of an ``else if``.
### ~
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Your game is ready!
Click **Compile** to move your program to the BBC micro:bit!
Have fun!
## Step 5: Are you the greatest?
Here is a way you can make your Rock Paper Scissors game better.
When button ``A`` is pressed,
the micro:bit will add `1` to your score.
Open the ``Game`` drawer, and then add the block ``change score by 1`` to your program,
like this:
```blocks
input.onButtonPressed(Button.A, () => {
game.addScore(1)
})
```
## Step 6: Prove you're the greatest!
After your micro:bit can add `1` to the score, show how many wins you have.
```blocks
input.onButtonPressed(Button.A, () => {
game.addScore(1)
basic.showString("WINS:")
basic.showNumber(game.score())
})
```
## Step 7: Staying honest
Success! Your micro:bit can track wins!
But what about losses?
Use the ``Game`` drawer to subtract `1` from your score when you press button `B`.
Here are all the blocks you will need:
```shuffle
input.onButtonPressed(Button.B, () => {
game.addScore(-1)
basic.showString("LOSSES:")
basic.showNumber(game.score())
})
```
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Click **Compile** to move your program to the BBC micro:bit!
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# Want to do more?
There are [10 great projects](/projects) waiting for you.