Some thoughts on the microbit

Paul Kinlan

It was my eldest son’s birthday the other day, and it was late in the evening on said Birthday and I thought “I will give my son the gift of learning how to program”. It worked as I expected, he looked at me, wrinkled his nose, and got back to playing Fifa sitting next to me whilst I smashed out a terrible game on the amazing microbit.

My quick summary is that I think it is an amazing litle device for quickly starting programming and getting into programming with hardware.

Arguably, I think the micro:bit is better than a Raspberry-pi or a Pi-zero for starting with Software and hardware programming.

There is an incredibly low barrier to getting started, you plug it into the USB open up a web browser, do some python and drop a hex file on to it and you can start to build something that you can interact with. There is nothing else that you have to do, you can get feedback on button clicks, get something on to the display and go from there.

Compare this with my flow on the Pi’s: Get SD-Card, Format and add linux, Get device, boot, show people how to use linux, load up an editor build some hw integrations.

Don’t get me wrong, I love the Pi ecosystem but I wanted something that my son could start to input on and interact with and see feedback within minutes and the micro:bit was perfect for this….. even though he really just went back to FIFA 2017.

Whilst my son was playing FIFA, I had a lot of fun with the micro:bit. I thought it would be fun to create a Breakout or Arkanoid clone. It would test the 25 pixel display and I could learn about basic input via the buttons.

Below is my code for game (it is terrible and has some bugs in).

from microbit import *

# quickly create a level of two rows, with pixels set to 0 hits and 1 hits
blocks = [[1 - i for j in range(5) ] for i in range(2)]
ball = [2, 3]
ball_direction = [1,-1]
paddle = [2, 4]
previous_game_time = running_time()
ball_timing = running_time()
game_time = running_time()
running = True

# Set up the board.
def setup_line(line, value):
    for i in range(5):
        display.set_pixel(i, line, value)

def draw_blocks():
    for x in range(5):
        for y in range(2):
            display.set_pixel(x, y, blocks[y][x])

def draw_ball():
    display.set_pixel(ball[0], ball[1], 4)

def draw_paddle():
    display.set_pixel(paddle[0], paddle[1], 5)
    display.set_pixel(paddle[0]+1, paddle[1], 5)

def move_ball():
    global ball
    ball = next_position()

def next_position():
    return [ball[0] + ball_direction[0], ball[1] + ball_direction[1]]

def check_ball_collisions():
    global running

    if ball[1] == 4:
        # Has the ball hit the bottom. Stop the ball and Game over
        ball_direction[0] = 0
        ball_direction[1] = 0
        running = False
        return

    # Has the ball hit the paddle.
    if ball[1] == 3 and (ball[0] == paddle[0] or ball[0] == paddle[0] + 1):
        # 3, so it doesn't embed in the paddle
        ball_direction[1] = -ball_direction[1]

    if ball[1] == 3 and (ball[0] == paddle[0] - 1 or ball[0] == paddle[0] + 2):
        # ball hit odd angle of paddle.. note might reflect it back up one day
        ball_direction[0] = -ball_direction[0]

    # Has the ball hit wall (left, right, top).  We can still hit something
    if ball[0] == 0 or ball[0] == 4:
        ball_direction[0] = -ball_direction[0]

    if ball[1] == 0:
        ball_direction[1] = -ball_direction[1]

    if ball[1] <= 2:
        # Blocks can only be in top two rows in this game
        if blocks[ball[1] - 1][ball[0]] > 0:
            # We hit a block, take a life from the block
            blocks[ball[1] -1][ball[0]] = blocks[ball[1] -1][ball[0]] -1
            # send the ball back down.
            ball_direction[1] = -ball_direction[1]


flipflop = 1

while running:
    display.clear()

    # get input
    if button_a.is_pressed() and paddle[0] >= 1:
        paddle[0] = paddle[0] - 1
    if button_b.is_pressed() and paddle[0] < 3:
        paddle[0] = paddle[0] + 1


    if game_time - ball_timing > 500:
        flipflop = flipflop ^ 1
        display.set_pixel(4, 4, flipflop)

        move_ball()
        check_ball_collisions()
        ball_timing = game_time

    # draw state
    draw_blocks()
    draw_ball()
    draw_paddle()

    previous_game_time = game_time
    game_time = running_time()

    sleep(100)

display.clear()
display.scroll('Game Over')

Here is an ever-up-to date gist.

There is a lot to like about the environment, but there are somethings that I think could be smoothed out:

  1. The Web Editor for Python is amazing but you have to DL the hex file and then move it the USB folder. It would be great if it could integrate with the experimental WebUSB API so that I could just press run and it would deploy on the device.
  2. Debugging is a pain, if you get an error the error is display on the 5x5 pixel display :) It would be great if we could either debug easily via my development machine, or if I had an emulator of the device that would have sped up the debug cycle.

Paul Kinlan

Trying to make the web and developers better.

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