Do not insert or remove an SD Card while the game is running. It is may corrupt the file system and the game will need to be reloaded. It may also corrupt the save file and all progress will be lost.
Progress of the game is automatically saved as you complete or unlock each level. This includes the password for the level, the score, and the amount of time left when you complete the level. The amount of space required is too much to be stored in nvram, so an SD card is used. It is automatically remounted as read/write when the game is loaded. You can still play the game without an SD card, but the state is not saved between loads of the game.
The purposes of the SaveState class include:
- Handling automatically mounting the SD Card and marking it as unavailable if it fails to load
- Handling loading the data and saving it as it is updated
- Keeping track of the passwords and scores as the game is played
By default, the save file is named chips.json, but can be renamed. If you do not have an SD card, that is detected when the game is first loaded and the game will continue to function like normal for the duration of the session. The only difference is that progress with regards to scoring and unlocking levels is not saved. You can tell if the SD Card has successfully loaded by watching the serial output.
If it loads successfully, you should see "SD Card detected" and if not, you should see "SD Card not detected. Level data will NOT be saved."
# SPDX-FileCopyrightText: 2025 Melissa LeBlanc-Williams
#
# SPDX-License-Identifier: MIT
from math import floor
import json
import board
from microcontroller import nvm
from digitalio import DigitalInOut, Pull
import busio
import sdcardio
import storage
SAVESTATE_FILE = "chips.json"
class SaveState:
def __init__(self):
self._levels = {}
self._has_sdcard = self._mount_sd_card()
if self._has_sdcard:
print("SD Card detected")
else:
print("SD Card not detected. Level data will NOT be saved.")
self.load()
self._sdcard = None
def _mount_sd_card(self):
self._card_detect = DigitalInOut(board.SD_CARD_DETECT)
self._card_detect.switch_to_input(pull=Pull.UP)
if self._card_detect.value:
return False
# Attempt to unmount the SD card
try:
storage.umount("/sd")
except OSError:
pass
spi = busio.SPI(board.SD_SCK, MOSI=board.SD_MOSI, MISO=board.SD_MISO)
try:
sdcard = sdcardio.SDCard(spi, board.SD_CS, baudrate=20_000_000)
vfs = storage.VfsFat(sdcard)
storage.mount(vfs, "/sd")
except OSError:
return False
return True
def save(self):
if not self._has_sdcard:
return
with open("/sd/" + SAVESTATE_FILE, "w") as f:
json.dump({"levels": self._levels}, f)
def load(self):
if not self._has_sdcard:
return
# Use try in case the file doesn't exist
try:
with open("/sd/" + SAVESTATE_FILE, "r") as f:
data = json.load(f)
self._levels = data["levels"]
except (OSError, ValueError):
pass
def set_level_score(self, level, score, time_left):
level_key = f"level{level}"
new_high_score = False
lower_time = False
if level_key not in self._levels:
self._levels[level_key] = {}
if score > self._levels[level_key].get("score", 0):
new_high_score = True
self._levels[level_key]["score"] = score
if time_left > self._levels[level_key].get("time_left", 0):
lower_time = True
self._levels[level_key]["time_left"] = time_left
self.save()
return new_high_score, lower_time
def add_level_password(self, level, password):
nvm[0] = level
for byte, char in enumerate(password):
nvm[1 + byte] = ord(char)
level_key = f"level{level}"
if level_key not in self._levels:
self._levels[level_key] = {}
self._levels[level_key]["password"] = password.upper()
self.save()
def find_unlocked_level(self, level_or_password):
if isinstance(level_or_password, int):
level_key = f"level{level_or_password}"
password = None
else:
level_key = None
password = level_or_password
# Look for level by number
if level_key in self._levels:
return level_or_password
for key, data in self._levels.items():
if "password" in data and data["password"] == password:
return int(key[5:])
return None
def calculate_score(self, level, time_left, deaths):
time_bonus = time_left * 10
level_bonus = floor(level * 500 * 0.8**deaths)
level_score = time_bonus + level_bonus
total_score = self.total_score
return time_bonus, level_bonus, level_score, total_score
def has_password(self, level, password):
level_key = f"level{level}"
if level_key in self._levels:
return self._levels[level_key]["password"] == password.upper()
return False
def level_score(self, level):
level_key = f"level{level}"
if (level_key in self._levels and "score" in self._levels[level_key] and
"time_left" in self._levels[level_key]):
return self._levels[level_key]["score"], self._levels[level_key]["time_left"]
return 0, 0
def is_level_unlocked(self, level):
level_key = f"level{level}"
if level_key in self._levels and "password" in self._levels[level_key]:
return True
return False
@property
def has_sdcard(self):
return self._has_sdcard
@property
def total_score(self):
total_score = 0
for data in self._levels.values():
if "score" in data:
total_score += data["score"]
return total_score
@property
def total_completed_levels(self):
completed_levels = 0
for data in self._levels.values():
if "score" in data:
completed_levels += 1
return completed_levels
Page last edited April 08, 2025
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