CircuitPython Usage
To use the game, you need to update code.py with the game program to the CIRCUITPY drive.
Thankfully, we can do this in one go. In the example below, click the Download Project Bundle button below to download the necessary libraries and the code.py file in a zip file.
Connect your board to your computer via a known good data+power USB cable. The board should show up in your File Explorer/Finder (depending on your operating system) as a flash drive named CIRCUITPY.
Extract the contents of the zip file, copy the lib directory files to CIRCUITPY/lib. Copy the code.py file to your CIRCUITPY drive. The program should self start.
Drive Structure
After copying the files, your drive should look like the listing below. It can contain other files as well, but must contain these at a minimum.
# SPDX-FileCopyrightText: 2025 Tim Cocks for Adafruit Industries
# SPDX-License-Identifier: MIT
import sys
import time
from micropython import const
import board
import picodvi
import framebufferio
import supervisor
import displayio
import terminalio
from adafruit_display_text.text_box import TextBox
from snake_helpers import World, Snake, GameOverException, SpeedAdjuster
# state machine constant
STATE_TITLE = const(0)
STATE_PLAYING = const(1)
STATE_PAUSED = const(2)
STATE_GAME_OVER = const(3)
# begin in the title state
CURRENT_STATE = STATE_TITLE
# movement key bindings, change to different letters if you want.
KEY_UP = "w"
KEY_LEFT = "a"
KEY_DOWN = "s"
KEY_RIGHT = "d"
KEY_PAUSE = "t"
# how many segments the snake will start with
INITIAL_SNAKE_LEN = 3
# variable for the players score
score = 0
# initialize display
displayio.release_displays()
fb = picodvi.Framebuffer(
320,
240,
clk_dp=board.CKP,
clk_dn=board.CKN,
red_dp=board.D0P,
red_dn=board.D0N,
green_dp=board.D1P,
green_dn=board.D1N,
blue_dp=board.D2P,
blue_dn=board.D2N,
color_depth=16,
)
display = framebufferio.FramebufferDisplay(fb)
# In future release the default HSTX display
# will get initialized by default by circuitpython
# display = supervisor.runtime.display
# load title splash screen bitmap
title_bmp = displayio.OnDiskBitmap("snake_splash.bmp")
# create a tilegrid for the title splash screen
title_tg = displayio.TileGrid(bitmap=title_bmp, pixel_shader=title_bmp.pixel_shader)
instructions_txt = TextBox(
terminalio.FONT,
text=f"Move: {KEY_UP}{KEY_LEFT}{KEY_DOWN}{KEY_RIGHT} Pause: {KEY_PAUSE}".upper(),
width=title_bmp.width,
height=16,
align=TextBox.ALIGN_CENTER,
)
instructions_txt.anchor_point = (0, 0)
instructions_txt.anchored_position = (0, title_bmp.height + 1)
# create a group for the title splash screen and put it in the center of the display
title_group = displayio.Group()
title_group.append(title_tg)
title_group.append(instructions_txt)
title_group.x = display.width // 2 - title_bmp.width // 2
title_group.y = display.height // 2 - title_bmp.height // 2
# initialize SpeedAdjuster to control how fast the snake is moving
speed_adjuster = SpeedAdjuster(12)
# initialize the world with enough room unused at the top for the score bar
world = World(height=28, width=40)
# move the world down to make room for the score bar
world.y = 16
# initialize a Snake instance and grow it to the appropriate size
snake = Snake(starting_location=[10, 10])
for i in range(INITIAL_SNAKE_LEN - 1):
snake.grow()
# add one of each type of apple to the world
world.add_apple(snake=snake, apple_sprite_index=World.APPLE_RED_SPRITE_INDEX)
world.add_apple(snake=snake, apple_sprite_index=World.APPLE_GREEN_SPRITE_INDEX)
# create a group to hold everything for the game
game_group = displayio.Group()
# add the world to the game group
game_group.append(world)
# create TextBox to hold the score in a bar at the top of the display
score_txt = TextBox(
terminalio.FONT, text=f"Score: {score}", color=0xFFFFFF, width=320, height=16
)
score_txt.anchor_point = (0, 0)
score_txt.anchored_position = (0, 2)
# add the score text to the game group
game_group.append(score_txt)
# create a TextBox to hold the game over message
game_over_label = TextBox(
terminalio.FONT,
text="",
color=0xFFFFFF,
background_color=0x000000,
width=display.width // 2,
height=80,
align=TextBox.ALIGN_CENTER,
)
# move it to the center of the display
game_over_label.anchor_point = (0, 0)
game_over_label.anchored_position = (
display.width // 2 - game_over_label.width // 2,
40,
)
# make it hidden, we'll show it when the game is over.
game_over_label.hidden = True
# add it to the game group
game_group.append(game_over_label)
# set the title group to show on the display
display.root_group = title_group
# draw the snake in it's starting location
world.draw_snake(snake)
# timpstamp of the game step render
prev_step_time = time.monotonic()
# variable to hold string read from the keyboard to get button presses
cur_btn_val = None
while True:
# current timestamp
now = time.monotonic()
# check if there is any keyboard input
available = supervisor.runtime.serial_bytes_available
# if there is some keyboard input
if available:
# read it into cur_btn_val
cur_btn_val = sys.stdin.read(available)
# change to lower-case before comparison
# so that it's case-insensitive.
cur_btn_val = cur_btn_val.lower()
else: # no keyboard input
# set to None to clear out previous value
cur_btn_val = None
# if the current state is title screen
if CURRENT_STATE == STATE_TITLE:
# if any button was pressed
if cur_btn_val is not None:
# set the visible group on the display to the game group
display.root_group = game_group
# update the current state to playing
CURRENT_STATE = STATE_PLAYING
# if game is being played
elif CURRENT_STATE == STATE_PLAYING:
# if up button was pressed
if cur_btn_val == KEY_UP.lower():
# if the snake is not already moving up or down
if snake.direction not in (snake.DIRECTION_DOWN, snake.DIRECTION_UP):
# change the direction to up
snake.direction = snake.DIRECTION_UP
# if down button was pressed
if cur_btn_val == KEY_DOWN.lower():
# if the snake is not already moving up or down
if snake.direction not in (snake.DIRECTION_DOWN, snake.DIRECTION_UP):
# change the direction to down
snake.direction = snake.DIRECTION_DOWN
# if right button was pressed
if cur_btn_val == KEY_RIGHT.lower():
# if the snake is not already moving left or right
if snake.direction not in (snake.DIRECTION_LEFT, snake.DIRECTION_RIGHT):
# change the direction to right
snake.direction = snake.DIRECTION_RIGHT
# if left button was pressed
if cur_btn_val == KEY_LEFT.lower():
# if the snake is not already moving left or right
if snake.direction not in (snake.DIRECTION_LEFT, snake.DIRECTION_RIGHT):
# change direction to left
snake.direction = snake.DIRECTION_LEFT
# if the pause button was pressed
if cur_btn_val == KEY_PAUSE.lower():
# change the state to paused
CURRENT_STATE = STATE_PAUSED
# if it's time to render a step of the game
if now >= prev_step_time + speed_adjuster.delay:
try:
# move the snake in the direction it's going
result = world.move_snake(snake)
# if a red apple was eaten
if result == World.APPLE_RED_SPRITE_INDEX:
# decrease the speed to slow down movement
speed_adjuster.decrease_speed()
# award score based on current speed and snake size
score += ((20 - speed_adjuster.speed) // 3) + snake.size
# update the score text in the top bar
score_txt.text = f"Score: {score}"
# if a green apple was eaten
elif result == World.APPLE_GREEN_SPRITE_INDEX:
# increase the speed to speed up movement
speed_adjuster.increase_speed()
# award score based on current speed and snake
# size plus bonus points for green apple
score += ((20 - speed_adjuster.speed) // 3) + 3 + snake.size
# update the score text in the top bar
score_txt.text = f"Score: {score}"
# if the game is over due to snake running into the edge or itself
except GameOverException as e:
# update the game over message with the score
output_str = (
f"Game Over\nScore: {score}\nPress P to play again\nPress Q to quit"
)
# set the message into the game over label
game_over_label.text = output_str
# make the game over label visible
game_over_label.hidden = False
# update the state to game over
CURRENT_STATE = STATE_GAME_OVER
# store the timestamp to compare with next iteration
prev_step_time = now
# if the game is paused
elif CURRENT_STATE == STATE_PAUSED:
# if the pause button was pressed
if cur_btn_val == KEY_PAUSE.lower():
# change the state to playing so the game resumes
CURRENT_STATE = STATE_PLAYING
# if the current state is game over
elif CURRENT_STATE == STATE_GAME_OVER:
# if the p button is pressed for play again
if cur_btn_val in {"p", "P"}:
# set next code file to this one
supervisor.set_next_code_file(__file__)
# reload
supervisor.reload()
# if the q button is pressed for exit
if cur_btn_val in {"q", "Q"}:
# break out of main while True loop.
break
Page last edited March 14, 2025
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