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Read multiple DS18B20 temperature sensors faster using Raspberry Pi

My custom sensor dashboard requests new readings every second.
This worked well, until I hooked up 3 DS18B20 temperature sensors (1-wire protocol, so all on 1 pin), which each take 750ms to provide new data.
This is the class I currently use to read the temperature of each sensor:
# ds18b20.py
# written by Roger Woollett
import os
import glob
import time
class DS18B20:
# much of this code is lifted from Adafruit web site
# This class can be used to access one or more DS18B20 temperature sensors
# It uses OS supplied drivers and one wire support must be enabled
# To do this add the line
# dtoverlay=w1-gpio
# to the end of /boot/config.txt
#
# The DS18B20 has three pins, looking at the flat side with the pins pointing
# down pin 1 is on the left
# connect pin 1 to GPIO ground
# connect pin 2 to GPIO 4 *and* GPIO 3.3V via a 4k8 (4800 ohm) pullup resistor
# connect pin 3 to GPIO 3.3V
# You can connect more than one sensor to the same set of pins
# Only one pullup resistor is required
def __init__(self):
# Load required kernel modules
os.system('modprobe w1-gpio')
os.system('modprobe w1-therm')
# Find file names for the sensor(s)
base_dir = '/sys/bus/w1/devices/'
device_folder = glob.glob(base_dir + '28*')
self._num_devices = len(device_folder)
self._device_file = list()
i = 0
while i < self._num_devices:
self._device_file.append(device_folder[i] + '/w1_slave')
i += 1
def _read_temp(self, index):
# Issue one read to one sensor
# You should not call this directly
# First check if this index exists
if index >= len(self._device_file):
return False
f = open(self._device_file[index], 'r')
data = f.read()
f.close()
return data
def tempC(self, index=0):
# Call this to get the temperature in degrees C
# detected by a sensor
data = self._read_temp(index)
retries = 0
# Check for error
if data == False:
return None
while (not "YES" in data) and (retries > 0):
# Read failed so try again
time.sleep(0.1)
#print('Read Failed', retries)
data = self._read_temp(index)
retries -= 1
if (retries == 0) and (not "YES" in data):
return None
(discard, sep, reading) = data.partition(' t=')
if reading == 85000:
# 85ºC is the boot temperature of the sensor, so ignore that value
return None
temperature = float(reading) / 1000.0
return temperature
def device_count(self):
# Call this to see how many sensors have been detected
return self._num_devices
I already tried to return the previous temperature reading if the current one isn't finished yet, however this didn't reduce the time it took to read a sensor, so I guess the only way is to do things asynchronously.
I could reduce the precision to reduce the time it takes per reading, but ideally I would read all of the sensors simultaneously on separate threads.
How can I best implement this? Or are there other ways to improve the reading speed of multiple DS18B20 sensors?
Thanks for any insights!

You're facing some limitations introduced by the Linux kernel driver. If you were interacting with the OneWire protocol directly, you would only have a single 750ms read cycle for all three sensors, rather than (3 * 750ms). When speaking the 1-wire protocol directly, you can issue a single "convert temperature" command to all devices on the bus, as described here, and then read all the sensors.
The Linux driver explicitly doesn't support this mode of operation:
If none of the devices are parasite powered it would be possible to convert all the devices at the same time and then go back to read individual sensors. That isn’t currently supported. The driver also doesn’t support reduced precision (which would also reduce the conversion time) when reading values.
That means you're stuck with a 750ms per device read cycle. Your best option is probably placing the sensor reading code in a separate thread, e.g.:
import glob
import threading
import time
# Note that we're inheriting from threading.Thread here;
# see https://docs.python.org/3/library/threading.html
# for more information.
class DS18B20(threading.Thread):
default_base_dir = "/sys/bus/w1/devices/"
def __init__(self, base_dir=None):
super().__init__()
self._base_dir = base_dir if base_dir else self.default_base_dir
self.daemon = True
self.discover()
def discover(self):
device_folder = glob.glob(self._base_dir + "28*")
self._num_devices = len(device_folder)
self._device_file: list[str] = []
for i in range(self._num_devices):
self._device_file.append(device_folder[i] + "/w1_slave")
self._values: list[float | None] = [None] * self._num_devices
self._times: list[float] = [0.0] * self._num_devices
def run(self):
"""Thread entrypoint: read sensors in a loop.
Calling DS18B20.start() will cause this method to run in
a separate thread.
"""
while True:
for dev in range(self._num_devices):
self._read_temp(dev)
# Adjust this value as you see fit, noting that you will never
# read actual sensor values more often than 750ms * self._num_devices.
time.sleep(1)
def _read_temp(self, index):
for i in range(3):
with open(self._device_file[index], "r") as f:
data = f.read()
if "YES" not in data:
time.sleep(0.1)
continue
disacard, sep, reading = data.partition(" t=")
temp = float(reading) / 1000.0
self._values[index] = temp
self._times[index] = time.time()
break
else:
print(f"failed to read device {index}")
def tempC(self, index=0):
return self._values[index]
def device_count(self):
"""Return the number of discovered devices"""
return self._num_devices
Because this is a thread, you need to .start() it first, so your
code would look something like:
d = DS18B20()
d.start()
while True:
for i in range(d.device_count()):
print(f'dev {i}: {d.tempC(i)}')
time.sleep(0.5)
You can call the tempC method as often as you want, because it's
just return a value from the _values array. The actual update
frequency is controlled by the loop in the run method (and the
minimum cycle time imposed by the sensors).

python-vlc switching playback media between launches

I'm trying to set up a system where my start-screen video loops until 1 of 2 buttons is pressed (GPIO buttons).
Then, the playback changes to either a video with subtitles or no-subtitles.
Once that has finished its play-through, it reverts back to the splash screen video.
I have additional tickers in here just to count the number of play-throughs per day for analytics. My Test device also only has 1 button hooked up which is why GPIO 18 is never used. Implementation will be identical to GPIO 17's, so once one is working the other won't be hard to match up.
Problem
When I launch the script, the media played is not always splash. The script also closes the window at the end of playback, and opens a new one to play the media. I believe this may be due to not establishing an xwindow (for raspberry pi).
Any advice?
#Vars
GPIO.setmode(GPIO.BCM)
GPIO.setup(17,GPIO.IN)
GPIO.setup(18,GPIO.IN)
update = True #Update to false to exit
def Main():
# Setup logs
print(date.today())
# Media Paths
path = "/home/pi/Videos/"
nosubs = path+"Content-NoSubs.mp4"
subs = path+"Content-Subtitles.mp4"
splash = path+"StartScreen.mp4"
Instance = vlc.Instance("-f")
playlist = set([splash,subs,nosubs])
url = [str(splash),str(subs),str(nosubs)] #Yes, this looks pretty redundant. Hopefully it's not.
#Setup the player
player = Instance.media_list_player_new()
Media = Instance.media_new(url[1])
Media_list = Instance.media_list_new(playlist)
Media.get_mrl()
player.set_media_list(Media_list)
playerState = {'State.NothingSpecial',
'State.Opening',
'State.Buffering',
'State.Playing',
'State.Paused',
'State.Stopped',
'State.Ended',
'State.Error'}
subsPlayed = 0
nosubsPlayed = 0
active = 0
playingMedia = 0
while update:
input = GPIO.input(17)
state = str(player.get_state())
if(state == playerState[0]):
player.play_item_at_index(0)
player.set_playback_mode(2)
if(state == playerState[7]):
player.play_item_at_index(0)
playingMedia = 0
if input == 1 and playingMedia == 0:
playingMedia = 1
player.play_item_at_index(1)
active +=1
nosubsPlayed +=1
print(playingMedia)
with open(str(date.today()))+'.txt','w' as file:
file.write("Active Views: " + active)
file.write("SubsPlayed: " + subsPlayed)
file.write("No Subs Played: " + nosubsPlayed)
Main()

So I figured out the solution, but not the problem's origin.
# Make my media paths into vlc.Media Objects
nosubs = vlc.Media(path+"Content-NoSubs.mp4")
subs = vlc.Media(path+"Content-Subtitles.mp4")
splash = vlc.Media(path+"SplashScreen.mp4")
#Setup the player
player = Instance.media_list_player_new()
Media_list = Instance.media_list_new()
Media_list.add_media(splash)
Media_list.add_media(subs)
Media_list.add_media(nosubs)
player.set_media_list(Media_list)
Media_list.lock()
Setting up each of the media by name in my list helps by switching the play function from play_item_at_index(int) to play_item(media)
Still not sure why it was kind of randomizing. My guess was that it changed the position of media in the list based on play through.
My next step will be to adjust this to work off of media_player and embedding playback into a tkinter window.

Stopping a function based on a value

I am running a python script on a raspberry-pi.
Essentially, I would like a camera to take a picture every 5 seconds, but only if I have set a boolean to true, which gets toggled on a physical button.
initially I set it to true, and then in my while(true) loop, I want to check to see if the variable is set to true, and if so, start taking pictures every 5 seconds. The issue is if I use something like time time.sleep(5), it essentially freezes everything, including the check. Combine that with the fact that I am using debouncing for the button, it then becomes impossible for me to actually toggle the script since I would have to press it exactly after the 5s wait time, right for the value check... I've been searching around and I think the likely solution would have to include threading, but I can't wrap my head around it. One kind of workaround I thought of would be to look at the system time and if the seconds is a multiple of 5, then take picture (all within the main loop). This seems a bit sketchy.
Script below:
### Imports
from goprocam import GoProCamera, constants
import board
import digitalio
from adafruit_debouncer import Debouncer
import os
import shutil
import time
### GoPro settings
goproCamera = GoProCamera.GoPro()
### Button settings
pin = digitalio.DigitalInOut(board.D12)
pin.direction = digitalio.Direction.INPUT
pin.pull = digitalio.Pull.UP
switch = Debouncer(pin, interval=0.1)
save = False #this is the variable
while(True):
switch.update()
if switch.fell:
print("Pressed, toggling value")
save = not save
if save:
goproCamera.take_photo()
goproCamera.downloadLastMedia()
time.sleep(5)

Here's something to try:
while(True):
switch.update()
if switch.fell:
print("Pressed, toggling value")
save = not save
if save:
current_time = time.time()
if current_time - last_pic_time >= 5:
goproCamera.take_photo()
goproCamera.downloadLastMedia()
last_pic_time = current_time
Depending on exactly what sort of behavior you want, you may have to fiddle with when and how often time.time() is called.

Cheers!
Maybe something like this?
import threading
def set_interval(func, sec):
def func_wrapper():
set_interval(func, sec)
func()
t = threading.Timer(sec, func_wrapper)
t.start()
return t
We call the function above inside the main loop.
Wrap your while loop content on a function:
def take_photo:
goproCamera.take_photo()
goproCamera.downloadLastMedia()
Now we create a flag initially set to False to avoid creating multiple threads.
Notice that I did this before the while loop. We just need a starting value here.
active = False
while(True):
switch.update()
if switch.fell:
print("Pressed, toggling value")
save = not save
if save: # we need to start taking photos.
if not active: # it is not active... so it is the first time it is being called or it has been toggled to save as True again.
photo_thread = set_interval(take_photo, 5) # grabbing a handle to the thread - photo_thread - so we can cancel it later when save is set to False.
active = True # marking as active to be skipped from the loop until save is False
else:
try: # photo_thread may not exist yet so I wrapped it inside a try statement here.
photo_thread.cancel() # if we have a thread we kill it
active = False #setting to False so the next time the button is pressed we can create a new one.
Let me know if it works. =)

What I ended up doing:
### Imports
from goprocam import GoProCamera, constants
import board
import digitalio
from adafruit_debouncer import Debouncer
import os
import time
import threading
### GoPro settings
gopro = GoProCamera.GoPro()
### Button settings
pin = digitalio.DigitalInOut(board.D12)
pin.direction = digitalio.Direction.INPUT
pin.pull = digitalio.Pull.UP
switch = Debouncer(pin, interval=0.1)
### Picture save location
dir_path = os.path.dirname(os.path.realpath(__file__))
new_path = dir_path+"/pictures/"
save = False
### Functions
def takePhoto(e):
while e.isSet():
gopro.take_photo()
gopro.downloadLastMedia()
fname = '100GOPRO-' + gopro.getMedia().split("/")[-1]
current_file = dir_path+'/'+fname
if os.path.isfile(current_file):
os.replace(current_file, new_path+fname) #move file, would be cleaner to download the file directly to the right folder, but the API doesn't work the way I thought it did
e.wait(5)
### Initial settings
e = threading.Event()
t1 = threading.Thread(target=takePhoto, args=([e]))
print("Starting script")
while(True):
switch.update()
if switch.fell:
#toggle value
save = not save
if save:
e.set() #should be taking pictures
else:
e.clear() #not taking pictures
if not t1.is_alive(): #start the thread if it hasn't been yet
if e.is_set():
t1.start()

How to automate control of Wemo light switch based on iPhone GPS

I'm writing a program to toggle the lights at my house based on my iPhone's GPS coordinates. Below is what I have so far. However, I feel like there must be a better way to do this. Is there a way to get GPS data without pinging my phone every five minutes?
So far I've tried the following with no joy:
Using Shortcuts and Scriptable I tried to write some JavaScript that would trigger when I got close to home. However, I could not figure out how to use await require('wemo-client') using scriptablify. I kept getting an error, "ReferenceError: Can't find variable: require".
IFTTT does not have a variable timed trigger so the lights won't turn off after 15 minutes. Also, I plan on adding a motion sensor trigger that is unsupported.
Pythonista is $10. Yes, I am that cheap.
Apple HomeKit does not support the model I'm using, Wemo Smart Light Switch F7C030.
The code below works, but I hate that I have to ping my phone every five minutes. I'd rather save battery life by firing this code once or twice a day, as needed.
Any suggestions would be greatly appreciated.
Code:
import sys
import time
import datetime
import os
from pyicloud import PyiCloudService
import pywemo
APPLE_ID = os.getenv('APPLE_ID') # Apple ID username
APPLE_ID_PASSWORD = os.getenv('APPLE_ID_PASSWORD') # Apple ID password
API = PyiCloudService(APPLE_ID, APPLE_ID_PASSWORD)
IPHONE = API.devices[1]
LOCATION = IPHONE.location()
FIVE = 300 # 5 * 60 seconds
FIFTEEN = 900 # 15 * 60 seconds
ONEMILE = 0.01449275362318840579710144927536 # one mile is 1/69 degrees lat or long
HOMELAT = # my home's latitude
HOMELONG = # my home's longitude
WEMOS = pywemo.discover_devices()
LEN_WEMOS = range(len(WEMOS))
# Two factor authentication to retrieve iPhone data
if API.requires_2fa:
import click
print("Two-step authentication required. Your trusted devices are:")
DEVICES = API.devices
for i, device in enumerate(DEVICES):
print(" %s: %s" % (i, device.get('deviceName', "SMS to %s" % device.get('phoneNumber'))))
DEF_DEVICE = click.prompt('Which device would you like to use?', default=0)
DEVICE = DEVICES[DEF_DEVICE]
if not API.send_verification_code(DEVICE):
print("Failed to send verification code")
sys.exit(1)
CODE = click.prompt('Please enter validation code')
if not API.validate_verification_code(DEVICE, CODE):
print("Failed to verify verification code")
sys.exit(1)
# Turn off the lights when I leave
def leavehome():
timenow = datetime.datetime.now()
print("Left home on {}".format(timenow.strftime("%B %d, %Y at %H:%M:%S")))
for wemo in LEN_WEMOS:
WEMOS[wemo].off()
# Turn on the lights for 15 minutes when I get home
def arrivehome():
timenow = datetime.datetime.now()
print("Arrived home on {}".format(timenow.strftime("%B %d, %Y at %H:%M:%S")))
# Loop through all Wemo devices
for wemo in LEN_WEMOS:
WEMOS[wemo].on()
time.sleep(FIFTEEN)
for wemo in LEN_WEMOS:
WEMOS[wemo].off()
# Automatically turn off the lights after 15 minutes - save electricity
def timeoff():
time.sleep(FIFTEEN)
for wemo in LEN_WEMOS:
WEMOS[wemo].off()
# Ping my phone for GPS data
def pingphone(prev):
mylat = LOCATION["latitude"]
mylong = LOCATION["longitude"]
logic(prev, mylat, mylong)
time.sleep(FIVE)
# Perform logic to determine if I'm home, out, arriving, or leaving
def logic(prev, lat, long):
inrange = (HOMELAT+ONEMILE >= lat >= HOMELAT-ONEMILE and HOMELONG+ONEMILE >= long >= HOMELONG-ONEMILE)
current = bool(inrange)
previous = prev
if current and not previous:
arrivehome()
elif previous and not current:
leavehome()
else:
timeoff()
pingphone(current)
# Run the script
pingphone(False)

How to watch tasklist for running tasks

I've been dealing with this for a while. I don't think I can find an easy solution. What I want to know is how many hours I play games.
Why does printing result_1 return 0 sometimes and 1 other times? Why doesn't it return "No tasks are running..." or show me the running task?
import subprocess
from time import *
from datetime import *
command_1 = "TASKLIST /FI \"IMAGENAME eq Application-steam*\"" #Code for finding the "Banished" game
no_task_respond_0 = "INFO: No tasks are running which match the specified criteria."
while True:
the_time = datetime.now()
result_1 = subprocess.call(command_1, shell=True) # running this code prints the result whether i want it or not
open_file = open("watcher.txt","w")
current_task_file = open_file.write(str(result_1))
print(current_task_file,"Inside of Current task FILE!!")
if str(current_task_file) == str(no_task_respond_0): #If no games are running then continue
continue
else: #If the game started then note the time
date_file = open("datefile.txt","a")
date_watcher = date_file.write(str(the_time)+"\n")
sleep(4)
When I close the game, this is the result that it returns:
**INFO: No tasks are running which match the specified criteria.**
**1 Inside of Current Task FILE!!**
This is the output while the game is running:
Image Name PID Session Name Session# Mem Usage
========================= ======== ================ =========== ============
Application-steam-x64.exe 14684 Console 1 298.588 K
**1 Inside of Current task FILE!!**
These 1s are from printing result_1.