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  • pySerial writes to Arduino Uno get buffered

    - by Bhaktavatsalam Nallanthighal
    I have a Python script that writes short messages to the serial port on my Arduino Uno board using pySerial. There is a loop and depending on some conditions, multiple writes can happen within a loop, something like this: while True: #Conditions block 1 if <CONDITION1>: serial.writelines("INIT") elif <CONDITION2>: serial.writelines("NEW") ... #Conditions block 2 if <CONDITION1>: # Fetch something from the Internet serial.writelines("CHECK") elif <CONDITION2>: # Fetch something from the Internet serial.writelines("STOP") ... But, when my Arduino board receives this it receives the first message as INIT, but the second one is being read as INITSTOP or INITCHECK and third one gets concatenated to the previous messages. My arduino program checks for specific message in this way: if(msg.equals("CHECK")) { // Do something } else if(msg.equals("INIT")) { // Do Something else } Can anyone guide me on this? BTW, I don't think the problem is with the Arduino as it works perfectly when I test it with the Serial Monitor available with the IDE. I've tried adding sleeps of upto 10 seconds before every write, but that did not work out.

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  • Pyserial : How to send data to drive SIPO

    - by bino oetomo
    Dear All .. I'm learning to drive a stepper motor with Python. It's hard now to find a PC with paralel port. So My plan is using a USB-Serial .. and a SIPO (serial in parallel out) shift register circuit. As you know with this circuit we need to send a binary data in series and this data will be stored in it's register. Next we need to send another one pulse to make it shift the data out to the out-port. How to do it using pyserial ? Sincerely -bino-

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  • Why is /dev/rfcomm0 giving PySerial problems?

    - by Travis G.
    I am connecting my Ubuntu box to a wireless readout setup over Bluetooth. I wrote a Python script to send the serial information through /dev/rfcomm0. The script connects fine and works for a few minutes, but then Python will start using 100% CPU and the messages stop flowing through. I can open rfcomm0 in a serial terminal and communicate through it by hand just fine. When I open it through a terminal it seems to work indefinitely. Also, I can swap the Bluetooth receiver for a USB cable, and change the port to /dev/ttyUSB0, and I don't get any problems over time. It seems either I'm doing something wrong with rfcomm0 or PySerial doesn't handle it well. Here's the script: import psutil import serial import string import time sampleTime = 1 numSamples = 5 lastTemp = 0 TEMP_CHAR = 't' USAGE_CHAR = 'u' SENSOR_NAME = 'TC0D' gauges = serial.Serial() gauges.port = '/dev/rfcomm0' gauges.baudrate = 9600 gauges.parity = 'N' gauges.writeTimeout = 0 gauges.open() print("Connected to " + gauges.portstr) filename = '/sys/bus/platform/devices/applesmc.768/temp2_input' def parseSensorsOutputLinux(output): return int(round(float(output) / 1000)) while(1): usage = psutil.cpu_percent(interval=sampleTime) gauges.write(USAGE_CHAR) gauges.write(chr(int(usage))) #write the first byte #print("Wrote usage: " + str(int(usage))) sensorFile = open(filename) temp = parseSensorsOutputLinux(sensorFile.read()) gauges.write(TEMP_CHAR) gauges.write(chr(temp)) #print("Wrote temp: " + str(temp)) Any thoughts? Thanks. EDIT: Here is the revised code, using Python-BlueZ instead of PySerial: import psutil import serial import string import time import bluetooth sampleTime = 1 numSamples = 5 lastTemp = 0 TEMP_CHAR = 't' USAGE_CHAR = 'u' SENSOR_NAME = 'TC0D' #gauges = serial.Serial() #gauges.port = '/dev/rfcomm0' #gauges.baudrate = 9600 #gauges.parity = 'N' #gauges.writeTimeout = 0 #gauges.open() gaugeSocket = bluetooth.BluetoothSocket(bluetooth.RFCOMM) gaugeSocket.connect(('00:06:66:42:22:96', 1)) filename = '/sys/bus/platform/devices/applesmc.768/temp2_input' def parseSensorsOutputLinux(output): return int(round(float(output) / 1000)) while(1): usage = psutil.cpu_percent(interval=sampleTime) #gauges.write(USAGE_CHAR) gaugeSocket.send(USAGE_CHAR) #gauges.write(chr(int(usage))) #write the first byte gaugeSocket.send(chr(int(usage))) #print("Wrote usage: " + str(int(usage))) sensorFile = open(filename) temp = parseSensorsOutputLinux(sensorFile.read()) #gauges.write(TEMP_CHAR) gaugeSocket.send(TEMP_CHAR) #gauges.write(chr(temp)) gaugeSocket.send(chr(temp)) #print("Wrote temp: " + str(temp)) It seems either Ubuntu must be closing /dev/rfcomm0 after a certain time or my Bluetooth receiver is messing things up. Even when the BluetoothError arises, the "connected" light on the receiver stays illuminated, and it is not until I power-cycle to receiver that I can reconnect. I'm not sure how to approach this problem. It's odd that the connection would work fine for a few minutes (seemingly a random amount of time) and then seize up. In case it helps, the Bluetooth receiver is a BlueSmirf Silver from Sparkfun. Do I need to be trying to maintain the connection from the receiver end or something?

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  • getting a pyserial not loaded error

    - by skinnyTOD
    I'm getting a "pyserial not loaded" error with the python script fragment below (running OSX 10.7.4). I'm trying to run a python app called Myro for controlling the Parallax Scribbler2 robot - figured it would be a fun way to learn a bit of Python - but I'm not getting out of the gate here. I've searched out all the Myro help docs but like a lot in-progress open source programs, they are a moving target and conflicting, out of date, or not very specific about OSX. I have MacPorts installed and installed py27-serial without error. MacPorts lists the python versions I have installed, along with the active version: Available versions for python: none python24 python25 python25-apple python26 python26-apple python27 python27-apple (active) python32 Perhaps stuff is getting installed in the wrong places or my PATH is wrong (I don't much know what I am doing in Terminal and have probably screwed something up). Trying to find out about my sys.path - here's what I get: import sys sys.path ['', '/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python27.zip', '/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7', '/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/plat-darwin', '/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/plat-mac', '/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/plat-mac/lib-scriptpackages', '/System/Library/Frameworks/Python.framework/Versions/2.7/Extras/lib/python', '/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-tk', '/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-old', '/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload', '/System/Library/Frameworks/Python.framework/Versions/2.7/Extras/lib/python/PyObjC', '/Library/Python/2.7/site-packages'] Is that a mess? Can I fix it? Anyway, thanks for reading this far. Here's the python bit that is throwing the error. The error occurs on 'try import serial'. # Global variable robot, to set SerialPort() robot = None pythonVer = "?" rbString = None ptString = None statusText = None # Now, let's import things import urllib import tempfile import os, sys, time try: import serial except: print("WARNING: pyserial not loaded: can't upgrade!") sys.exit() try: input = raw_input # Python 2.x except: pass # Python 3 and better, input is defined try: from tkinter import * pythonver = "3" except: try: from Tkinter import * pythonver = "2" except: pythonver = "?"

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  • How can I fix "[Error 6] The handle is invalid." with PySerial

    - by alnorth29
    I'm trying to connect to my phone from my Windows 7 PC using PySerial with the following code: import wmi import serial c = wmi.WMI() modem = c.query("SELECT * FROM Win32_POTSModem").pop() ser = serial.Serial(modem.AttachedTo, modem.MaxBaudRateToSerialPort) try: ser.write('at \r\n') print ser.readline() finally: ser.close() But get the following error on the write call: Traceback (most recent call last): File "D:\Alasdair\Documents\Python Scripts\Phone Interface\test.py", line 14, in <module> ser.write('at \r\n') File "C:\Python26\Lib\site-packages\serial\serialwin32.py", line 255, in write raise SerialException("WriteFile failed (%s)" % ctypes.WinError()) SerialException: WriteFile failed ([Error 6] The handle is invalid.) I've tried connecting with TeraTerm and that works fine, so it's not a problem with the connection to the phone itself. I've been searching around for ages trying to find a solution but haven't come up with anything that works. Any ideas?

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  • Python Access Parallel Port

    - by PPTim
    Hi, I've been trying to access the parallel port with pyParallel, which is in the same sourceforge as PySerial: http://sourceforge.net/projects/pyserial/files/ I'm getting a WidowsError: exception: priviledged instruciton. Has anyone used this module before? import parallel p = parallel.Parallel() Traceback (most recent call last): File "<interactive input>", line 1, in <module> File "C:\Python26\lib\site-packages\parallel\parallelwin32.py", line 74, in __init__ self.ctrlReg = _pyparallel.inp(self.ctrlRegAdr) WindowsError: exception: priviledged instruction

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  • Python PyBluez loses Bluetooth connection after a while

    - by Travis G.
    I am using Python to write a simple serial Bluetooth script that sends information about my computer stats periodically. The receiving device is a Sparkfun BlueSmirf Silver. The problem is that, after the script runs for a few minutes, it stops sending packets to the receiver and fails with the error: (11, 'Resource temporarily unavailable') Noticing that this inevitably happens, I added some code to automatically try to reopen the connection. However, then I get: Could not connect: (16, 'Device or resource busy') Am I doing something wrong with the connection? Do I need to occasionally reopen the socket? I'm not sure how to recover from this type of error. I understand that sometimes the port will be busy and a write operation is deferred to avoid blocking other processes, but I wouldn't expect the connection to fail so regularly. Any thoughts? Here is the script: import psutil import serial import string import time import bluetooth sampleTime = 1 numSamples = 5 lastTemp = 0 TEMP_CHAR = 't' USAGE_CHAR = 'u' SENSOR_NAME = 'TC0D' #gauges = serial.Serial() #gauges.port = '/dev/rfcomm0' #gauges.baudrate = 9600 #gauges.parity = 'N' #gauges.writeTimeout = 0 #gauges.open() filename = '/sys/bus/platform/devices/applesmc.768/temp2_input' def parseSensorsOutputLinux(output): return int(round(float(output) / 1000)) def connect(): while(True): try: gaugeSocket = bluetooth.BluetoothSocket(bluetooth.RFCOMM) gaugeSocket.connect(('00:06:66:42:22:96', 1)) break; except bluetooth.btcommon.BluetoothError as error: print "Could not connect: ", error, "; Retrying in 5s..." time.sleep(5) return gaugeSocket; gaugeSocket = connect() while(1): usage = psutil.cpu_percent(interval=sampleTime) sensorFile = open(filename) temp = parseSensorsOutputLinux(sensorFile.read()) try: #gauges.write(USAGE_CHAR) gaugeSocket.send(USAGE_CHAR) #gauges.write(chr(int(usage))) #write the first byte gaugeSocket.send(chr(int(usage))) #print("Wrote usage: " + str(int(usage))) #gauges.write(TEMP_CHAR) gaugeSocket.send(TEMP_CHAR) #gauges.write(chr(temp)) gaugeSocket.send(chr(temp)) #print("Wrote temp: " + str(temp)) except bluetooth.btcommon.BluetoothError as error: print "Caught BluetoothError: ", error time.sleep(5) gaugeSocket = connect() pass gaugeSocket.close() EDIT: I should add that this code connects fine after I power-cycle the receiver and start the script. However, it fails after the first exception until I restart the receiver. P.S. This is related to my recent question, Why is /dev/rfcomm0 giving PySerial problems?, but that was more about PySerial specifically with rfcomm0. Here I am asking about general rfcomm etiquette.

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  • As a Qt GUI programmer, how to improve (career & skill)?

    - by linjunhalida
    hello, I'm a python & Qt programmer, and my daily job is create small PC GUI programs ship with hardware devices. the problem is, My job is simple, read/write data to device by using serial port(pyserial), display and edit data(PyQt + PyQwt), that's all. although I'm a linux user, my program is running under windows XP, but thanks to PyQt, I can still develop under linux. And I'm always afraid of being replaced by the people cheaper and younger than me in the future. (I'm 26 now.. not too much time for playing..) So I need improve myself, and make me more competitive in the global market, and I like programming, and want coding till the end of my life. any roadmap suggestion?

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  • How do I make a USB RS232 dongle show up in /dev/ttyUSB* ?

    - by mtrw
    I have a couple of FTDI based USB to Rs232 serial dongles. Sometimes when I plug them into my Ubuntu 10.04 laptop, they show up as /dev/ttyUSB0 and /dev/ttyUSB1, which is what I want to have happen. But sometimes they don't. When they don't, sometimes rebooting fixes the problem and sometimes it doesn't. They always show up in lsusb hanging off of Bus 5: Bus 005 Device 003: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC Bus 005 Device 002: ID 0403:6001 Future Technology Devices International, Ltd FT232 USB-Serial (UART) IC Bus 005 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub I can see them if I do ls /dev/bus/usb/005 as 002 and 003. But if I pass /dev/bus/usb/005/002 to pyserial, which is what I'm using to access /dev/ttyUSBx, I get SerialException("Could not open port: [Errno 13] Permission denied: '/dev/bus/usb/005/002'",).

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  • C: cross-platform RS232 serial library?

    - by Hamza
    Hi folks, I am looking for an open source cross-platform library for working with the serial port in C, something along the lines of the awesome pyserial library (Unfortunately I have to use C for this application) I have only found this one: http://www.teuniz.net/RS-232/ and that doesn't seem to have mention OSX compatibility. Any recommendations/comments would be greatly appreciated. Thanks.

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  • receive string with chars

    - by Meloun
    Hi all, i am quite new in python. I am receiving (through pyserial) string with data values. How can I parse these data to particular data structure? I know that 0-1 byte : id 2-5 byte : time1 =>but little endian (lsb first) 6-9 byte : time2 =>but little endian (lsb first) and I looking for a function: def parse_data(string): data={} data['id'] = ?? data['time1'] = ?? data['time2'] = ?? return data thanks

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  • Python, Raspberry, and Arduino Communication

    - by user2924156
    I have been working with my Raspberry, Arduino and applying some Python to make them communicate. I also installed pyserial. If I use IDLE and try the following I get my expected results. >>> import serial >>> ser = serial.Serial('/dev/ttyUSB0',115200) >>> ser.write('x:1\n') 8 >>> ser.readline() 'X:1\r\n' If I write a python scrip and run it I don't get anything back. Here is my python script. import serial ser = serial.Serial('/dev/ttyUSB0', 115200) ser.write('!x:1\n') ser.readline() I am new to Python so looking for some help to understand they this works in IDLE but not as a python script run from terminal. Thanks.

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  • USB packets - receive wrong data

    - by regorianer
    i have a little python script which shows me the packets of an enocean device and does some events depending on the packet type. unfortunately it doesn't work because i'm getting wrong packets. Parts of the python script (used pySerial): Blockquote ser = serial.Serial('/dev/ttyUSB1',57600,bytesize = serial.EIGHTBITS,timeout = 1, parity = serial.PARITY_NONE , rtscts = 0) print 'clearing buffer' s = ser.read(10000) print 'start read' while 1: s = ser.read(1) for character in s: sys.stdout.write(" %s" % character.encode('hex')) print 'end' ser.close() output baudrate 57600: e0 e0 00 e0 00 e0 e0 e0 e0 e0 00 e0 e0 00 00 00 00 00 00 00 e0 e0 e0 00 00 00 00 e0 e0 e0 00 00 e0 e0 e0 e0 e0 00 e0 00 e0 e0 e0 e0 e0 00 e0 e0 00 00 00 00 00 00 e0 e0 e0 00 00 00 00 e0 e0 e0 00 00 e0 e0 e0 output baudrate 9600: a5 5a 0b 05 10 00 00 00 00 15 c4 56 20 6f a5 5a 0b 05 00 00 00 00 00 15 c4 56 20 5f linux terminal baudrate 57600: $stty -F /dev/ttyUSB1 57600 $stty < /dev/ttyUSB1 speed 57600 baud; line = 0; eof = ^A; min = 0; time = 0; -brkint -icrnl -imaxbel -opost -onlcr -isig -icanon -iexten -echo -echoe -echok -echoctl -echoke $while (true) do cat -A /dev/ttyUSB1 ; done myfile $hexdump -C myfile 00000000 4d 2d 60 4d 2d 60 5e 40 4d 2d 60 5e 40 4d 2d 60 |M-M-^@M-^@M-| 00000010 4d 2d 60 4d 2d 60 4d 2d 60 4d 2d 60 5e 40 4d 2d |M-M-M-M-^@M-| 00000020 60 4d 2d 60 5e 40 5e 40 5e 40 5e 40 5e 40 5e 40 |M-^@^@^@^@^@^@| 00000030 5e 40 4d 2d 60 4d 2d 60 4d 2d 60 5e 40 5e 40 5e |^@M-M-M-`^@^@^| 00000040 40 5e 40 4d 2d 60 4d 2d 60 4d 2d 60 |@^@M-M-M-`| 0000004c linux terminal baudrate 9600: $hexdump -C myfile2 00000000 5e 40 5e 55 4d 2d 44 56 30 4d 2d 3f 5e 40 5e 40 |^@^UM-DV0M-?^@^@| 00000010 5e 55 4d 2d 44 56 20 5f |^UM-DV _| 00000018 the specification says: 0x55 sync byte 1st 0xNNNN data length bytes (2 bytes) 0x07 opt length byte 0x01 type byte CRC, data, opt data und nochmal CRC but I'm not getting this packet structure. The output of the python script differs from the one I get via the terminal. I also wrote the python part with C, but the output is the same as with python As the USB receiver a BSC-BoR USB Receiver/Sender is used The EnOcean device is a simple button

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  • Re-order list in Python to ensure it starts with check values.

    - by S_Swede
    Dear all, I'm reading in serial data using Pyserial, to populate a list of 17 values (1byte each) at a sampling rate of 256Hz. The bytes I ultimately want to use are the 5th to 8th in the list. Providing no bytes are dropped, the first two values of the stream are always the same ('165','90'). I'm getting quite a few dropped values though, and my list values are shifting, so when I read the 5th-8th bytes, they aren't the correct values. I've partially combatted this by ensuring that before the wanted segement is captured, the first few values are checked against what they should be (i.e. if mylist[0]==165 &....). This is crude but ok since the chances of these two values appearing adjacent to each other in the list elsewhere is small. The problem is that this means as soon as the bytes shift, I'm losing a load of values, until it eventually realigns. My question is: what code can I use to either: a) Force the list to realign once it has been detected that it no longer starts with 165,90. (elif....). b) Detect where '165' & '90' are (next to each other) in the list and extract the values I want in relation to their position (next but one, onwards). Thanks in advance S_S Just noticed from the related Qs that I could use mylist.append(mylist.pop(0)) multiple times until they are in the right place. Is there a better way that anyone can suggest?

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