pxt-calliope/docs/getting-started.md

Getting started

~avatar

Are you ready to build cool BBC micro:bit programs?

Here are some challenges for you. Arrange the blocks in the editor to make real programs that work!

~

Happy face

Use the Basic drawer in the editor (to the left) to drag out and arrange three blocks (two show leds and one forever block) to create this program:

basic.forever(() => {
    basic.showLeds(`
        . . . . .
        . # . # .
        . . . . .
        # . . . #
        . # # # .
        `)
    basic.showLeds(`
        . . . . .
        . . . . .
        . . . . .
        . . . . .
        . . . . .
        `)
});

When you run this program (click the Play button) you will see a smiley face, then a blank screen, then a smiley again -- it never stops! (That's because of the forever block.)

Click Compile to move your program to the BBC micro:bit!

Happy unhappy face

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)!

basic.forever(() => {
    basic.showLeds(`
        . . . . .
        . # . # .
        . . . . .
        # . . . #
        . # # # .
        `)
    basic.showLeds(`
        . . . . .
        . # . # .
        . . . . .
        . # # # .
        # . . . #
        `)
});

Click Compile to move your program to the BBC micro:bit!

Your turn!

Pile up more show leds blocks to create an animation! Create an animation with at least 5 pictures. What does this animation show?

basic.forever(() => {
    basic.showLeds(`
        . . . . .
        . # . # .
        . . . . .
        # . . . #
        . # # # .
        `)
    basic.showLeds(`
        . . . . .
        . # . # .
        . . . . .
        # # # # #
        . . . . .
        `)
    basic.showLeds(`
        . . . . .
        . # . # .
        . . . . .
        . # # # .
        # . . . #
        `)
    basic.showLeds(`
        . . . . .
        . # . # .
        . . . . .
        # # # # #
        . . . # #
        `)
    basic.showLeds(`
        . . . . .
        # . # . .
        . . . . .
        # . . . #
        . # # # .
        `)
    basic.showLeds(`
        . . . . .
        . . # . #
        . . . . .
        # . . . #
        . # # # .
        `)
});

Click Compile to move your program to the BBC micro:bit!

~hint

You can find the show leds block in the Basic part of the editor.

~

Button A and button B

This program will show the word ANTEATER on the LED screen when you press button A.

input.onButtonPressed(Button.A, () => {
    basic.showString("ANTEATER");
});

~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.

input.onButtonPressed(Button.B, () => {
    basic.showString("BANANA");
});

~hint

You can find the letter B by clicking the letter A on the onButtonPressed block.

~

Click Compile to move your program to the BBC micro:bit!

Your turn!

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?

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 shakes the micro:bit. (Ouch!)

input.onGesture(Gesture.Shake, () => {
    basic.showLeds(`
. . . . .
. # . # .
. . . . .
. # # # .
# . . . #`);
});

Click Compile to move your program to the BBC micro:bit!

Pins

You can also use the pins as buttons. (The pins are the holes in the 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.

input.onPinPressed(TouchPin.P0, () => {
    basic.showLeds(`
. # . # .
# . # . #
# . . . #
. # . # .
. . # . .`);
});

Click Compile to move your program to the BBC micro:bit!

~hint

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!

~

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.

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:

~

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:

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.

Clear up the blocks and add the blocks below.

input.onGesture(Gesture.Shake, () => {
    
})

Next, when you shake the micro:bit, it should pick a random number from 0 to 2 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:

input.onGesture(Gesture.Shake, () => {
    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 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:

input.onGesture(Gesture.Shake, () => {
    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.

Make the else if part check if the variable item is 1. Then add a show leds block with a picture of a rock.

input.onGesture(Gesture.Shake, () => {
    let item = Math.random(3)
    if (item == 0) {
        basic.showLeds(`
            # # # # #
            # . . . #
            # . . . #
            # . . . #
            # # # # #
            `)
    } 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:

input.onGesture(Gesture.Shake, () => {
    let item = Math.random(3)
    if (item == 0) {
        basic.showLeds(`
            # # # # #
            # . . . #
            # . . . #
            # . . . #
            # # # # #
            `)

    } else if (item == 1) {
        basic.showLeds(`
            . . . . .
            . # # # .
            . # # # .
            . # # # .
            . . . . .
            `)
    } else {
        basic.showLeds(`
            # # . . #
            # # . # .
            . . # . .
            # # . # .
            # # . . #
            `)
    }
})

~hint

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.

~

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:

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.

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:

input.onButtonPressed(Button.B, () => {
    game.addScore(-1)
    basic.showString("LOSSES:")
    basic.showNumber(game.score())
})

Click Compile to move your program to the BBC micro:bit!

Want to do more?

There are 10 great projects waiting for you.