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I love the wireless capabilities of python on the BBC microbit and I’ve been using it with some success in myYear 8 classes.
I thought I’d have a go at writing a wireless Pong game in Python it took me a lot longer than I expected for various reasons. I really wanted to have the same code running on both microbits, but I soon abandoned that as too complex. Much easier to have one microbit Player A controlling the game and deciding who gets a point and when. Player B is the ‘slave’ only sending its left and right paddle moves back to Player A and mirroring (literally) Player A’s screen.
I was keen to have each screen the same rather than extending a long screen like a wired version I’ve seen. This is because I want each player to be able to be quite far apart, so seeing the other player’s screen isn’t necessary.
How to playFlash Player A code (below) on to one Microbit using Mu , and Player B on to a separate microbit. You can optionally connect a headphone or buzzer to pins 0 and 1 on each microbit for some audio feedback joy.
Power up Player B first it will wait for messages from Player A. Then power up Player A. The game starts straight away with the ball the bright dot in the middle of the screen moving in a random direction. Move your paddle left and right using A and B buttons. If you fail to hit the ball when it reaches your end the other player gets a point (points tallies are not shown on the screen) and the first player to 5 points wins. To play again you both need to press the reset button on the back of the microbits.
How it worksPlayer B is the easy one to explain. It runs a loop constantly polling for messages and keypresses. If you press button A to move left, or B to move right, it sends a message with your bat’s new position. It also listens for different kinds of messages from player A’s microbit. They all start with different code letters:
p + a number is the position of player A’s bat.
x and y messages give the current location of the ball, which is then inverted using a dictionary look-up table called ‘ bat_map ‘.
a and b messages give the respective scores or player A and B.
If a player reaches the winning score (5) it breaks out of the loop and plays a happy song (Nyan cat) if player B has won and a sad song (funeral march) is player A has won.
Player A is the master controller. It picks a random direction for the ball to start moving and bounces the ball if it hits any of the sides. If it hits the top or bottom and a player’s bat isn’t in the way, the other player gets a point. It has a crude timer using variables counter and delay every time it reaches 1000 it moves the ball (I couldn’t work out how to get proper timers to work in Microbit Python if indeed this is possible). If a player hits the ball with their bat it speeds up a bit.
It sends messages (as described above) to Player B with the ball position, score and player A bat position. The game ends in the same way as player B’s code described above, except you get the happy tune if player A wins and the sad one if player B wins.
How to modYou can make the game faster by making the value of delay smaller. You can also make it last longer by increasing the value of winning_score in both sets of code.
A nice extension would be to add more sound (when you hit the ball for example) and to add levels with the game getting faster each time someone wins a game.
Let me know how you get on with it and if you have any other ideas for improvements the physics of the ball bouncing is one area that I could do with help on!
Image may be NSFW.
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Here’s the player A code:
# Pongo by @blogmywiki # player A code - with points import radio import random from microbit import * from music import play, POWER_UP, JUMP_DOWN, NYAN, FUNERAL a_bat = 2 # starting position of player A bat b_bat = 2 # starting position of player B bat bat_map = {0: 4, 1: 3, 2: 2, 3: 1, 4: 0} ball_x = 2 # starting position of ball ball_y = 2 directions = [1, -1] # pick a random direction for ball at start x_direction = random.choice(directions) y_direction = random.choice(directions) delay = 1000 # used as a crude timer counter = 0 # used as a crude timer a_points = 0 b_points = 0 winning_score = 5 game_over = False def move_ball(): global ball_x, ball_y, x_direction, y_direction, counter, a_bat, b_bat, a_points, b_points, delay display.set_pixel(ball_x, ball_y, 0) ball_x = ball_x + x_direction ball_y = ball_y + y_direction if ball_x < 0: # bounce if hit left wall ball_x = 0 x_direction = 1 if ball_x > 4: # bounce if hit right wall ball_x = 4 x_direction = -1 if ball_y == 0: if ball_x == b_bat: # bounce if player B hit ball ball_y = 0 y_direction = 1 delay -= 50 # speed up after bat hits else: play(POWER_UP, wait=False) # A gets point if B missed ball a_points += 1 ball_y = 0 y_direction = 1 radio.send('a'+str(a_points)) # transmit points if ball_y == 4: # bounce if player A hits ball if ball_x == a_bat: ball_y = 4 y_direction = -1 delay -= 50 # speed up after bat hits else: play(JUMP_DOWN, wait=False) # player B gets point if A misses b_points += 1 ball_y = 4 y_direction = -1 radio.send('b'+str(b_points)) counter = 0 radio.send('x'+str(ball_x)) # transmit ball position radio.send('y'+str(ball_y)) radio.on() # like the roadrunner while not game_over: counter += 1 display.set_pixel(a_bat, 4, 6) # draw bats display.set_pixel(b_bat, 0, 6) display.set_pixel(ball_x, ball_y, 9) # draw ball if button_a.was_pressed(): display.set_pixel(a_bat, 4, 0) a_bat = a_bat - 1 if a_bat < 0: a_bat = 0 radio.send('p'+str(a_bat)) if button_b.was_pressed(): display.set_pixel(a_bat, 4, 0) a_bat = a_bat + 1 if a_bat > 4: a_bat = 4 radio.send('p'+str(a_bat)) incoming = radio.receive() if incoming: display.set_pixel(b_bat, 0, 0) b_bat = bat_map[int(incoming)] if counter == delay: move_ball() if a_points == winning_score or b_points == winning_score: game_over = True if a_points > b_points: play(NYAN, wait=False) display.scroll('A wins!') else: play(FUNERAL, wait=False) display.scroll('B wins!') display.scroll('Press reset to play again')Here’s the Player B code:
# Pongo by @blogmywiki # player B code import radio from microbit import * from music import play, POWER_UP, JUMP_DOWN, NYAN, FUNERAL a_bat = 2 # starting position of player A bat b_bat = 2 # starting position of player B bat bat_map = {0: 4, 1: 3, 2: 2, 3: 1, 4: 0} ball_x = 2 # starting position of ball ball_y = 2 a_points = 0 b_points = 0 winning_score = 5 game_over = False radio.on() # like the roadrunner def parse_message(): global a_bat, incoming, bat_map, ball_x, ball_y, a_points, b_points msg_type = incoming[:1] # find out what kind of message we have received msg = incoming[1:] # strip initial letter from message if msg_type == 'p': display.set_pixel(a_bat, 0, 0) their_bat = int(msg) # mirror their bat position a_bat = bat_map[their_bat] if msg_type == 'x': display.set_pixel(ball_x, ball_y, 0) ball_x = bat_map[int(msg)] if msg_type == 'y': display.set_pixel(ball_x, ball_y, 0) ball_y = bat_map[int(msg)] if msg_type == 'a': a_points = int(msg) play(JUMP_DOWN, wait=False) if msg_type == 'b': b_points = int(msg) play(POWER_UP, wait=False) while not game_over: display.set_pixel(b_bat, 4, 6) display.set_pixel(a_bat, 0, 6) display.set_pixel(ball_x, ball_y, 9) # draw ball if button_a.was_pressed(): display.set_pixel(b_bat, 4, 0) b_bat = b_bat - 1 if b_bat < 0: b_bat = 0 radio.send(str(b_bat)) if button_b.was_pressed(): display.set_pixel(b_bat, 4, 0) b_bat = b_bat + 1 if b_bat > 4: b_bat = 4 radio.send(str(b_bat)) incoming = radio.receive() if incoming: parse_message() if a_points == winning_score or b_points == winning_score: game_over = True if a_points < b_points: play(NYAN, wait=False) display.scroll('B wins!') else: play(FUNERAL, wait=False) display.scroll('A wins!')