I have a program that is supposed to take joystick position readings from an arduino (over serial), and translate them to mouse movements on my computer.
There is only one problem with this...
The string to integer conversion is way too slow, and it takes forever for the movements to register. I need either a faster way to convert a string to an integer value, or a way to skip the conversion altogether.
This is my current code:
import serial
import pyautogui
import time
ser = serial.Serial('COM3', 9600, timeout=1)
while True:
time.sleep(0.0001)
ser_bytes = ser.readline()
decoded_bytes = ser_bytes[0:len(ser_bytes)-2].decode("utf-8")
pos = decoded_bytes.split(':')
xpos = int(pos[0])
ypos = int(pos[1])
print("x:", xpos, " y:", ypos)
pyautogui.move(xpos, ypos)
Note: Output from arduino has 3 values:
0:0:0
First number: x
Second number: y
Third number: joystick button
Perhaps something like this will work? This way you can read more than one line of input for each time you call move(). Some lines of input will be ignored, but that seems necessary if you're getting input faster than you can use it.
import serial
import pyautogui
import time
ser = serial.Serial('COM3', 9600, timeout=1)
while True:
time_to_move = time.time() + 0.001
while True:
ser_bytes = ser.readline()
if time.time() >= time_to_move:
break
x_bytes, y_bytes = ser_bytes[:-2].split(b':')
x, y = int(x_bytes), int(y_bytes)
pyautogui.move(x, y)
Hello friends I need write some script to measure low power on Arduino analog pin and read it on my computer in Python. I write simple script what allow me to read serial data from USB no problem in this I get reading in range 0.00 - 25.00, equal power on analog pin, but I cant make script show me data how I wish.
import serial
import time
import sys
#ser = serial.Serial('/dev/ttyUSB0',9600) # Linux
ser = serial.Serial('COM13', 9600, timeout=0) # Windows
ser.flushInput()
ser.flushOutput()
while True:
data1 = ser.readline()
if data1 == 2.54:
print ("low")
elif data1 == 2.69:
print ("hi")
elif data1 == 2.57:
print ("center")
else:
print (data1)
time.sleep(1)
Some thing I write wrong and script not show me low, center, hi, value then its reached.
Having if data1 == 2.54 is a very limited range in my experience the values will jump around a bit unless you have your Arduino perform some rounding and have it send the value 2.54 else it would be better to use a >=. To decode the received data you can use data1.decode() this will stop you getting the encoded string in the format b'10\r\n' and will instead give you 10.
here is how i would write the code.
data1 = ser.readline()
data1 = data1.decode()
if data1 >= 20:
print ("high")
elif data1 >= 15:
print ("medium")
elif data1 >= 10:
print ("low")
else:
print("the value is below 10")
print (data1)
time.sleep(1)
hope this helps.
I find solution if some one need it :
if (data1.strip() == '2.54'):
works for me perfect , the answer find here : Python checking for serial string in If statement , Big thanks to #micromoses
I am trying to make an LCD display to display both the current temperature and the humidity at the same time in different lines. I have a sample code as below. The problem is that when the temperature goes above say 50C, I want the humidity reading to stop as well. I have 2 thread running at the same time, reading from both sensors.
#all important imports are here
def main():
# Very simplified code, not actual.
tempP = Process(target=temperature)
humidP = Process(target=humidity)
tempP.start()
humidP.start()
def temperature():
while True:
#ADC printing to LCD code is here
temperatureReading = ADC.channel(0)
if temperatureReading > 50:
humidP.terminate() # Does not work, I still see the humidity on
the screen with overlapping characters
I have a MCP3008 connected to RPi and 2 x Force Sensitive Resistor - Square connected to the MCP3008. The sensors are laying side by side horisontal on my desk and I can read and print the data (0-100) from both sensors (sensor1 and sensor2) separately. I just can't come up with any idea of python code to detect when I touch sensor1 (left) and move my finger to sensor2 (right).
In addition I need to know how many milliseconds it takes from that I touch sensor1 until I lifted from sensor2.
from time import sleep
from gpiozero import MCP3008
sensor1 = MCP3008(1) # Pin 2 on the ADC
sensor2 = MCP3008(2) # Pin 3 on the ADC
# Read data from the ADC
def getData(readSensor):
value = readSensor
rawValue = value.value
return rawValue
while True:
print('Sensor1 = {0:.0f}'.format(getData(sensor1)*100))
print('Sensor2 = {0:.0f}'.format(getData(sensor2)*100))
print('')
sleep(0.1)
You are going to need to timestamp the events and then use the time stamps to determine what action to take. Something like the below might help you.
if getData(sensor1) > TOUCH_THRESHOLD:
sensor1LastPressedAt = time.time()
Do the same for sensor2 and compare the time stamps.
(TOUCH_THRESHOLD is the value that you measure to be someone touching the button)
I need to read a temperature reading from a DS18B20 sensor using Raspberry Pi 3 and Python.
The problem is the refresh rate of the sensor (~1 sec)
I need to read from sys/bus/w1/devices/28-041670f43bff/w1_slave and use the integer i get to display a temperature on a 7 segment display connected directly to my GPIOs (not using any hardware multiplexing - i2c....etc)
In order to display a two digit temperature, I need to turn on and off the digits really fast (faster than the sensor refreshes)
This is the small piece of code used to get the integer temperature:
def temperature():
with open ("/sys/bus/w1/devices/28-041670f43bff/w1_slave") as q:
r=q.read()
temp=r[69:71]
t=int (temp)
return t
But i need to call this function many times per second in order to get a good display on the 7 segment display.
This is how i thought of doing it:
#the temperature() function returns a two digit int
while True:
GPIO.output(31,0)
GPIO.output(temp[temperature()/10], 1) # temp is a dictionary used to know which segments to light up to show numbers
time.sleep(0.0005)
GPIO.output(31,1)
GPIO.output(37,0)
GPIO.output(temp[temperature()%10], 1)
time.sleep(0.0005)
GPIO.output(37,1)
But this code just makes one digit light up, wait ~1sec, light up the other digit, wait ~1sec.....and so on.
Any ideas of how to do this are very appreciated.
Rather than implement this functionality on your own, you should instead use the libraries out there that address this particular bit of your code inherently. In this case, I'd suggest you use W1ThermSensor. You can find the documentation at:
https://github.com/timofurrer/w1thermsensor
and you can install it using:
pip install w1thermsensor
It does support the DS18B20, and offers an exact analogue to your use case in the README.
From the docs for the package:
from w1thermsensor import W1ThermSensor
sensor = W1ThermSensor()
temperature_in_celsius = sensor.get_temperature()
temperature_in_fahrenheit = sensor.get_temperature(W1ThermSensor.DEGREES_F)
temperature_in_all_units = sensor.get_temperatures([
W1ThermSensor.DEGREES_C,
W1ThermSensor.DEGREES_F,
W1ThermSensor.KELVIN
])
In many cases, particularly for popular hardware devices, you'll find that there are libraries already available to use within python, and that will all you to quickly move on to writing the bits of code unique to your own particular needs.
Note: According to the technical discussion in the following link, if the DS18B20 is set to 12-bit temperature resolution, the temperature conversion will take 750 ms, or 3/4 of a second. If you set the hardware to do 9-bit resolution, the conversion time in hardware is 93.75 ms. I suspect this is the root of your once-per-second issue.
https://www.maximintegrated.com/en/app-notes/index.mvp/id/4377
There is some discussion of this issue in this Question:
https://raspberrypi.stackexchange.com/questions/14278/how-to-change-ds18b20-reading-resolution
See the second Answer, regarding the configDS18B20 utility.
With the resolution set to 9-bit, you may be able to adjust the w1thermsensor RETRY_DELAY_SECONDS / RETRY_ATTEMPTS value combination in the source code and get what you need. It's unclear to me if the retry delay has any affect on the actual polling of the device. It looks like it is there for device finding. Though, as I said, that interval may impact polling a single device. I simply didn't read through the source code enough to see when and where it comes into play.
Happy New Year!
I'd throw the display routine into its own thread so that you don't have to think about it in your main loop. The code below should demonstrate this concept. Set "testing" to False to see if it works with your hardware.
#!/usr/bin/python
import time
import threading
import Queue
import random
# Set this to False to read the temperature from a real sensor and display it on a 7-digit display.
testing = True
def temperature_read(q):
# Read the temperature at one second intervals.
while True:
if testing:
r = '-' * 69 + '%02d' % (random.randrange(100)) + 'blahblah' * 4
else:
r = open('/sys/bus/w1/devices/28-041670f43bff/w1_slave', 'r').read()
print r
# The temperature is represented as two digits in a long string.
# Push the digits into the queue as a tuple of integers (one per digit).
q.put((int(r[69]), int(r[70])))
# Wait for next reading.
# (Will w1_slave block until the next reading? If so, this could be eliminated.)
time.sleep(1.0)
def temperature_display(q):
# Display the temperature.
# Temperature is two digits, stored separately (high/low) for more efficient handling.
temperature_h = temperature_l = 0
while True:
# Is there a new temperature reading waiting for us?
if not q.empty():
temperature = q.get()
# If it's None, we're done.
if temperature is None:
break
# Load the two digits (high and low) representing the temperature.
(temperature_h, temperature_l) = temperature
if testing:
print 'displayH', temperature_h
time.sleep(0.05)
print 'displayL', temperature_l
time.sleep(0.05)
else:
GPIO.output(31,0)
GPIO.output(temperature_h, 1) # temp is a dictionary used to know which segments to light up to show numbers
time.sleep(0.0005)
GPIO.output(31,1)
GPIO.output(37,0)
GPIO.output(temperature_l, 1)
time.sleep(0.0005)
GPIO.output(37,1)
# Clean up here. Turn off all pins?
# Make a queue to communicate with the display thread.
temperature_queue = Queue.Queue()
# Run the display in a separate thread.
temperature_display_thread = threading.Thread(target=temperature_display, args=(temperature_queue,))
temperature_display_thread.start()
# Run the reader.
try:
temperature_read(temperature_queue)
except:
# An uncaught exception happened. (It could be a keyboard interrupt.)
None
# Tell the display thread to stop.
temperature_queue.put(None)
# Wait for the thread to end.
temperature_display_thread.join()
To support another reading (transmission), I just put it in the read loop rather than adding another thread for it. I changed the queue so that you could easily move it to another thread but I suspect you'll add more inputs so this is probably a reasonable way to do it unless the read frequency of one needs to be much different. (Even then, you could do things with counters in the loop.)
#!/usr/bin/python
import time
import threading
import Queue
import random
# Set this to False to read the temperature from a real sensor and display it on a 7-digit display.
testing = True
def observe(q):
while True:
# Make a temperature reading.
if testing:
r = '-' * 69 + '%02d' % (random.randrange(100)) + 'blahblah' * 4
else:
r = open('/sys/bus/w1/devices/28-041670f43bff/w1_slave', 'r').read()
print 'temperature ->', r
# The temperature is represented as two digits in a long string.
# Push the digits into the queue as a tuple of integers (one per digit).
q.put(('temperature', int(r[69]), int(r[70])))
# Make a transmission reading.
if testing:
r = random.randrange(1,6)
else:
r = 0 # Put your transmission reading code here.
print 'transmission ->', r
q.put(('transmission', r))
# Wait for next reading.
# (Will w1_slave block until the next reading? If so, this could be eliminated.)
time.sleep(1.0)
def display(q):
# Display the temperature.
# Temperature is two digits, stored separately (high/low) for more efficient handling.
temperature_h = temperature_l = transmission = 0
while True:
# Is there a new temperature reading waiting for us?
if not q.empty():
reading = q.get()
# If it's None, we're done.
if reading is None:
break
elif reading[0] == 'temperature':
# Load the two digits (high and low) representing the temperature.
(x, temperature_h, temperature_l) = reading
elif reading[0] == 'transmission':
(x, transmission) = reading
if testing:
print 'displayH', temperature_h
time.sleep(0.05)
print 'displayL', temperature_l
time.sleep(0.05)
print 'transmission', transmission
time.sleep(0.05)
else:
GPIO.output(31,0)
GPIO.output(temperature_h, 1) # temp is a dictionary used to know which segments to light up to show numbers
time.sleep(0.0005)
GPIO.output(31,1)
GPIO.output(37,0)
GPIO.output(temperature_l, 1)
time.sleep(0.0005)
GPIO.output(37,1)
# Clean up here. Turn off all pins?
# Make a queue to communicate with the display thread.
readings_queue = Queue.Queue()
# Run the display in a separate thread.
display_thread = threading.Thread(target=display, args=(readings_queue,))
display_thread.start()
# Observe the inputs.
try:
observe(readings_queue)
except:
# An uncaught exception happened. (It could be a keyboard interrupt.)
None
# Tell the display thread to stop.
readings_queue.put(None)
# Wait for the thread to end.
display_thread.join()
Here's a version which only reads the temperature every tenth time but reads the transmission every time. I think you'll see how to easily tweak this to meet your needs.
I would make separate threads for each reader but it would complicate the thread management quite a bit.
#!/usr/bin/python
import time
import threading
import Queue
import random
# Set this to False to read the temperature from a real sensor and display it on a 7-digit display.
testing = True
def observe(q):
count = 0
while True:
# Only read the temperature every tenth time.
if (count % 10 == 0):
# Make a temperature reading.
if testing:
r = '-' * 69 + '%02d' % (random.randrange(100)) + 'blahblah' * 4
else:
r = open('/sys/bus/w1/devices/28-041670f43bff/w1_slave', 'r').read()
print 'temperature ->', r
# The temperature is represented as two digits in a long string.
# Push the digits into the queue as a tuple of integers (one per digit).
q.put(('temperature', int(r[69]), int(r[70])))
# Make a transmission reading.
if testing:
r = random.randrange(1,6)
else:
r = 0 # Put your transmission reading code here.
print 'transmission ->', r
q.put(('transmission', r))
# Wait for next reading.
if testing:
time.sleep(0.5)
else:
time.sleep(0.1)
count += 1
def display(q):
# Display the temperature.
# Temperature is two digits, stored separately (high/low) for more efficient handling.
temperature_h = temperature_l = transmission = 0
while True:
# Is there a new temperature reading waiting for us?
if not q.empty():
reading = q.get()
# If it's None, we're done.
if reading is None:
break
elif reading[0] == 'temperature':
# Load the two digits (high and low) representing the temperature.
(x, temperature_h, temperature_l) = reading
elif reading[0] == 'transmission':
(x, transmission) = reading
if testing:
print 'displayH', temperature_h
time.sleep(0.05)
print 'displayL', temperature_l
time.sleep(0.05)
print 'transmission', transmission
time.sleep(0.05)
else:
GPIO.output(31,0)
GPIO.output(temperature_h, 1) # temp is a dictionary used to know which segments to light up to show numbers
time.sleep(0.0005)
GPIO.output(31,1)
GPIO.output(37,0)
GPIO.output(temperature_l, 1)
time.sleep(0.0005)
GPIO.output(37,1)
# Clean up here. Turn off all pins?
# Make a queue to communicate with the display thread.
readings_queue = Queue.Queue()
# Run the display in a separate thread.
display_thread = threading.Thread(target=display, args=(readings_queue,))
display_thread.start()
# Observe the inputs.
try:
observe(readings_queue)
except:
# An uncaught exception happened. (It could be a keyboard interrupt.)
None
# Tell the display thread to stop.
readings_queue.put(None)
# Wait for the thread to end.
display_thread.join()