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# Copyright (c) 2022 David Steele <dsteele@gmail.com>
#
# SPDX-License-Identifier: GPL-2.0-or-later
# License-Filename: LICENSE
#
"""
blink.py
Add support to blink the green led on a Raspberry pi one time, for a half sec.
https://mlagerberg.gitbooks.io/raspberry-pi/content/5.2-leds.html
"""
import re
import time
from pathlib import Path
from typing import List
brightPaths: List[Path] = [
Path("/sys/class/leds/led0/brightness"),
Path("/sys/class/leds/ACT/brightness"),
]
triggerPaths: List[Path] = [
Path("/sys/class/leds/led0/trigger"),
Path("/sys/class/leds/ACT/trigger"),
]
modelPath: Path = Path("/sys/firmware/devicetree/base/model")
def bright_path():
try:
return [x for x in brightPaths if x.exists()][0]
except IndexError:
return None
def trigger_path():
try:
return [x for x in triggerPaths if x.exists()][0]
except IndexError:
return None
def onval() -> str:
"""A "1" turns on the led."""
return "1"
def offval() -> str:
"""Value to turn the led off."""
return "0" if onval() == "1" else "1"
def can_blink() -> bool:
"""Is this a Pi with a blinkable green led?"""
return bright_path() and trigger_path()
def get_trigger() -> str:
"""Save the current led trigger, for later restoration."""
text: str = trigger_path().read_text()
match = re.search(r"\[(.+)\]", text)
mode: str
if match:
mode = match.group(1)
else:
mode = "none"
return mode
def set_trigger(trigger: str) -> None:
"""Set the green led trigger."""
trigger_path().write_text(trigger)
def blink(times: int = 1) -> None:
"""Blink the green led once."""
if can_blink():
oldtrig = get_trigger()
try:
set_trigger("gpio")
except OSError:
set_trigger("input")
bright_path().write_text(offval())
for _ in range(times):
time.sleep(0.25)
bright_path().write_text(onval())
time.sleep(0.5)
bright_path().write_text(offval())
time.sleep(0.25)
set_trigger(oldtrig)
if __name__ == "__main__":
print(can_blink())
if can_blink():
print(get_trigger())
blink(3)
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