Solder In The Veins » Python

Simple Power Loss Detector with SMS Notification

Peter — Mon, 28 Jun 2010 21:40:26 +0000

After having a few un-expected power outages this year, it got me thinking about how I could easily (and cheaply) be alerted (preferably via SMS) should one occur. With a laptop running Linux, a little bit of Python and some easily obtainable hardware and software, I come up with a simple method of doing just that. Read on for the code and set-up instructions.

What You’ll Need

A Laptop or netbook running Linux (This won’t work with a Desktop PC)
Gammu (a management application for cellular devices)
The acpi system utility.
The Python Interpreter (Version 2.6.)
The commands, time and datetime Python modules
The Python bindings for Gammu.
A GSM modem or Phone that is compatible with Gammu (in my case, I’m using a Huawei E160 HSDPA USB modem with a Prepaid SIM card on the O2 network in the UK.)

Installing and Configuring the Software

Ubuntu/Debian users can install Gammu, the Gammu Python bindings and the acpi utility using the following command:

apt-get install gammu python-gammu acpi

The only configuration we’ll have to do here is to Gammu. First, determine what serial port device your GSM modem is connected to by running the dmesg command. If your using a USB dongle like me, the serial port device will be prefixed with /dev/ttyUSB

Once you’ve found the serial port device, enter the command gammu-config into the terminal to configure Gammu for use with your modem. You should be presented with something similar to the screenshot below:

gammu-config Configuration Menu Screen (Click on the image for a full-sized version.)

The only thing you need to worry about here is the Port option. Just replace the value in this option with the serial port device that corresponds to your GSM modem, then select the Save option to save the new configuration.

The Code

The Python script (pwralarm.py) which handles the job of detecting mains power outages and sending notifications can be found on the Software page. You will need to extract the script from the zip archive and configure it for your own use before it can be used. To configure the script for your own use, just set the variable mobileno at the top of the script to the Mobile/Cellular number you would like SMS notifications to be sent to by entering the number between the quotes.

Everything should now be good to go. To use the script,, make sure you have your GSM modem connected and your laptop/netbook plugged into the mains first, then type the command ./pwralarm.py to execute the script.

The script will run in an infinite loop and If the mains power source is disconnected (which is determined by the script running the acpi -a command and looking at the output) this will be detected by the script and an SMS notification message sent using the SendSMS() method of the Gammu module. To stop the script, just hold down the CTRL and C keys in the terminal you’re running the script in.

In Conclusion…

Ok, so this is a very, very, very ugly hack, but if you’re like me and you use a laptop as your main PC, which spends most of it’s time anchored to a desk and connected to the mains, you should find this useful as a way to alert you to possible power cuts or if your laptop is disconnected from the mains for any reason, for that matter (theft detection device, anyone?)

Hope it’s useful to someone. Feel free to leave any feedback in the comments or you can always get in touch with me via the Contact page on this site.

From HPR: Python Roundtable Discussion

Peter — Thu, 11 Feb 2010 06:55:20 +0000

This may be old news to some of you but I thought it was interesting enough to warrant a blog post.

The Podcast site Hacker Public Radio has a rather interesting episode about the current and future plans for the development of Python. Hope it’s useful to someone.

Handy Link: bpython

Peter — Thu, 31 Dec 2009 18:56:32 +0000

bpython is a Python interpreter interface on steroids! It’s main features are:

Syntax Highlighting
A save function (to save code you’ve entered to a file)
Auto-intending (we all know how important correct indenting is when you’re writing python scripts!)
Auto-Completion which displays suggestions for any built-in functions, helping you to get the syntax for a statement spot-on without having to dig through reference manuals. The auto-completion feature also helps with import declarations, showing you a list of available modules as you type.

Installation in Ubuntu is as painless as typing sudo apt-get install bpython Other packages are available for Debian, Fedora and OpenSUSE as well. You can also obtain the source code from here and compile it yourself if need be.

If you need any help with using bpython, then check out the project’s webpage. Hope this is useful to someone.

Happy new year!

Handy Link: “Invent with Python”

Peter — Tue, 29 Dec 2009 23:33:57 +0000

Need an accessible guide to learning Python that won’t send you to sleep? “Invent with Python” is just what you need!

Invent Your Own Computer Games with Python, 2nd Edition (to give it its full title) is a book written by Al Sweigart. It is available for free on-line in both HTML and PDF format. You can download the PDF format from here.

The book is released under a Creative Commons licence and is aimed at people who are completely new to programming.

Comprised of 19 Chapters (at the time this post was written), it guides the reader through the basic concepts (Installation of Python, use of the Python interactive shell, Variables, functions, etc) and some of the more advanced stuff as well.

The coding examples in the book are all games (so you can actually have some fun with what you create as you go through the book!), which increase in complexity as the chapters progress.

There is also a Blog related to the book, so you can keep up with any future additions that are made to it.

Taken the Python Challenge?

Peter — Fri, 16 Oct 2009 22:59:27 +0000

Want a great way to learn a programming language and have some fun? Why not take the Python Challenge. Just found out about this little gem on hackaday and thought I’d post it here to help spread the word.

The Python Challenge site consists of a series of levels ( 33 levels at present) in which you have to solve puzzles of increasing complexity using code you write yourself. Each puzzle solution then gives you access to the next level.

The site also has a great community behind it, with forums if you get really stuck and need a hint.

From Hackaday: Arduino Snow Clock

Peter — Wed, 01 Jul 2009 18:13:23 +0000

This Alarm Clock Arduino hack , featured on hackaday, has to be one of the most innovative uses of an Arduino and Python I have seen! The maker, insingertech, has published full instructions on his hack here.

He goes into great detail on his build process and the diagrams (for the Relay Driver part of his circuit, especially) really help to explain things.

The only critisism I can think of here is that perhaps he should have used an Ethernet Shield for the network connectivity element of his project instead of a PC/Laptop.

Webthermo: Web-based Temperature Monitor

Peter — Fri, 13 Mar 2009 15:58:23 +0000

Ok, so someone has already beaten me to it (and done a excellent job of it as well) with the whole web-based temperature monitoring thing, but anyway… Here’s Webthermo!

Webthermo, my follow-up to Ardthermo, is a small, web-enabled Python script which uses the CherryPy HTTP Python framework. It allows you to monitor temperature (in both Celsius and Fahrenheit units) over the Internet (using the port-fowarding facility of your Router), or on your own LAN via a web browser, your favorite RSS reader or a WAP-capable Mobile phone, using the same Arduino sketch and hardware setup as was used for Ardthermo.

It’s still in the early stages of development at the moment, so its still a bit rough around the edges but it works well enough. You can get a copy of the Python script, which also includes the Arduino sketch needed for the hardware side of things, from the Software page.

System Requirements and instructions on how to use Webthermo can be found below. Enjoy everyone!

System Requirements

Software

Python 2.5.2 or above with the CherryPy (version 3.1.1) and Threading modules installed.
Linux recommended. Use of Ubuntu is assumed in this guide, but this should work under Windows, Mac OS X, etc as well (Could any MAC or Windows users out there post their experiences with using this script? )

You don’t need to use a seperate Webserver, such as Apache, as the server component is provided by the CherryPy module.

Hardware

The hardware requirements and instructions for setting up the Measurement circuit are the same as in the Arduino Remote Thermometer article, so I won’t repeat them here. Have a look at the instructions there and make sure you have everything setup and the thermometer sketch uploaded to the Arduino before continuing.

Installing Software Dependencies

The Threading module should already be included with your Python installation. The CherryPy module can be installed by issuing the following command at the terminal:

sudo apt-get install python-cherrypy3

Configuring Webthermo

Before you use Webthermo, you’ll need to configure it. Open up the webthermo.py file (this is the main program, the obtaindata.py file is just a companion module) in your favorate text editor and scroll down to the Configuration Options section. A description of the Configuration options can be found below:

ArduinoPort: The serial port device your Arduino is connected to.

MonitorLocation: A short description of the location Webthermo is monitoring. This will show on all web pages as well as in the RSS feeds descriptions.

ServerPort: The port webthermo will listen on for connections.

Refresh_Interval: Sets the delay between page auto-refreshes. (This is only applicable to the home page.)

Users: The maximum number of Concurent Users you want Webthermo to be able to serve. The Default setting is 5.

Using Webthermo

To use Webthermo, open a terminal, go to the directory where you unpacked Webthermo, change to the bin subdirectory and issue the following command:

./webthermo.py

The script will then execute. You can stop the script by pressing Ctrl-C.

To check that everything’s working, load up a web browser and point it to the address and port number Webthermo is running on. You should then get the homepage in your browser. (See screenshot below for an example.)

Webthermo homepage. Click for full-sized image.

You can access the RSS feeds by appending /rss to the end of the URL. The WAP readings page can be accessed by appending /wap and the lite (plain-text version, suitable for PDA’s and older web browsers) can be accessed by appending /lite to the end of the URL.

Hope you find this little script useful. Until next time, good bye and Happy Hacking.

Fun with PyRSSI, an Arduino and Twitter

Peter — Sat, 07 Mar 2009 16:40:33 +0000

In this little project, the RSSI value (detected by a small python script) is used to control 3 LED’s on an Arduino. The LED’s are used to indicate the proximity (in terms of Far Away, Slightly Closer and Very Close) of a paired device relative to the PC running the script. The python script can also send a message to Twitter when the paired Bluetooth device is in close proximity to the PC.

The Arduino Sketch and companion Python script are both in the zip file rssitracker.zip which can be downloaded from the Software page.

What you need

Hardware:

1x Arduino
1x Solderless Breadboard
3x LED’s (Different Colours if possible. I’ve used Red, Blue and Green to indicate Far Away, Slightly Closer and Very Close proximity.)
1x Bluetooth Dongle (If you don’t have built-in Bluetooth on your machine.)
A Bluetooth device to pair with the PC.

Software:

Linux
Python with the PyRSSI, pyBluez and Twitter modules installed.
Swig
The Python and Bluetooth development libraries.

You will also need to register a Twitter account to use the Twitter Announce features. You can sign up for free here.

Installing the Software Components

Start off by installing pyBlueZ, swig, python-twitter and the development libraries for Python and Bluetooth. For Ubuntu users, installing these components is as easy as issuing the following command:

sudo apt-get install python-twitter python-bluez swig libbluetooth-dev python-all-dev

The installation of PyRSSI, on the other hand, requires a couple more steps. Here are the steps I taken:

Download the archive (tar.gz or tar.bz2) from here and uncompress to a directory of your choice.
Change to the directory where you uncompressed PyRSSI and issue the following command to complete the installation:

sudo python setup.py install

This should install the PyRSSI module and its dependencies to the correct directory.

Hardware Setup

The hardware side of this project is simple and consists of 3 LED’s connected to the Digital pins 2, 4 and 7 of the Arduino. If anyone wants an pic or Circuit diagram putting up, I’ll be more than happy to do so.

Pairing a Bluetooth device

Now that everything is connected up and all software components are installed, we need a Bluetooth device paired to the PC so we can use it. First, make sure the Bluetooth device is in Discoverable mode.

In Ubuntu, you can just load the Bluetooth Setup Wizard by right-clicking on the Bluetooth icon on the top bar of the desktop and selecting the Setup New Device option then just follow the steps.

Getting the Device’s MAC address

Now that the device is paired to the PC we need to get it’s MAC address. You can use the following command in Ubuntu to get the Name and MAC address of any discoverable device:

hcitool scan

When hcitool has finished scanning for devices, you should get output similar to that in the screenshot below:

hcitool Command: Example Output. Click here to view the full-sized version

Have a look at the top entry that I’ve highlighted. You can see the Devices name ‘V630i‘ on the right-hand side, and it’s corresponding MAC address ‘00:1A:75:A0:32:DC” on the left-hand side.

Using the Software

First of all, upload the Arduino sketch (bthoming_dev.pde) to the Arduino. When the sketch has been uploaded successfully, open up the python script (rssitracker.py) and configure it to your needs. A list of the configuration options and what they do can be found below:

ArduinoPort:

Set to the serial port device your Arduino is connected to.

DEV_MAC:

Sets the MAC address of your paired Bluetooth device.

UseTwitter:

Determines whether the Twitter feature is used. Set to True to use it and False to not use it.

TwitterUser:

The Username of Your Twitter Account.

TwitterPass:

The Password of your Twitter account.

TwitterThis:

The message you want to ‘Twitter’ when the Bluetooth device is in close proximity

The three options below configure the RSSI threshold values. What I’ve found from using pyRSSI is that any RSSI value of 0 and above indicates Very Close Proximity, while a RSSI value of -1 or below indicates Very Far or Out Of Range. So bear that in mind when setting the options below:

VeryClose:

You can set the trigger value for when the bluetooth device is very close to the PC.

AwayFromPC:

You can set the trigger value for when the bluetooth device is away from the PC, but not too far away from it.

VeryFarAway:

You can set the trigger value for when the bluetooth device is very far away from the PC.

When you’ve set all the configuration values to your preferences then connect up the Arduino and execute the Python script. There’s no command line arguments to enter here so just type: ‘./rssitracker.py’ to run it.

Limitations

This was just a 5-minute hack and is bound to have problems, so don’t rely on it for anything just yet; I just wanted get it up on here to show you all what you could do with the PyRSSI module. I should hopefully be able to get an improved version of this up in the next few days or so. Until then, Enjoy.

Arduino-based Talking & Remote Thermometer

Peter — Mon, 02 Mar 2009 03:34:38 +0000

After recently getting my hands on an Arduino Duemilanove, I came across this Sketch on Arduino Playground that allowed an Arduino to function as a temperature measuring device with the addition of a few cheap and easily obtainable components.

Deciding to take things a step further, I wrote a Python script to create a DIY temperature measuring device that could be used both locally, via the command line, as well as remotely, using a googlemail account to check the temperature of a room. You can grab a copy of this script, called “Ardthermo”, from the Software page.

This article should give all the info you need to know to build this little project for yourself and make use of the Ardthermo script. Enjoy.

What you’ll need

Hardware:

1x Arduino with at least 1 free Analog input port.

1x Solderless Breadboard (to try the circuit out on.)

1x 10k resistor

1x 10k NTC (Negative Temperature Coefficient) Thermistor.

Software:

Linux (Ubuntu Recommended. All instructions in this article assume that Ubuntu is installed on your PC.)

The Festival Text To Speech software program. (Optional, but needed if you want the temperature reading ‘Spoke’ to you as well well as printed on the screen.)

A Googlemail account (You can sign up for free here)

Python version 2.5.2 or above with termios support compiled in and the libgmail, pySerial and getpass Python modules installed.

The Arduino IDE software package (Get it from here.)

My Python script, Ardthermo, for the PC (get it from the Software page.)

My slightly modified version of the Temperature Measurement Sketch for the Arduino which is bundled in with the Ardthermo script. (I take NO credit for this Sketch at all, as all I’ve done to it is modify it a little bit to suit my needs.)

Construction

Ok, lets get the Arduino-side of the project up and running by putting the Temperature Measuring circuit together. In the rest of this guide, I make the assumption that you’re using a Solderless Breadboard but soldering the circuit together onto a bit of Vero or Matrix Board should be a trivial task for a beginner.

You’ll need to use the Power (+5v), Gnd (Ground) and one of the Analog-in connectors (Pin 0) on the Arduino. On mine, the Analog-In connectors are located near the bottom right-hand corner of the board and the Power connectors are just to the left of them. The image below should explain this better:

Click for Full-Sized version

You will need to set up the 10K NTC thermistor and 10K resistor on your breadboard (if you have one.) You might be able to see how everything is hooked up from the video near the top of the article (sorry about the rubbish quality), but the schematic diagram below shows how everything should fit together better than the vid.

Schematic Diagram for Temperature Measuring circuit

On the diagram above, VR1 represents the 10K NTC thermistor and R2 represents the 10K resistor. Be sure to check all connections between the Arduino and the Measuring circuit, as well as the USB or Serial connection between the PC and Arduino before continuing.

Installing Software components

So, now we have everything connected up it’s time to configure all the software components you’ll need. This section will concentrate on installing the Python modules, uploading the Thermometer Sketch to the Arduino and using the Ardthermo script. Installation of the Arduino IDE is outside the scope of this article but information on getting it setup under Ubuntu can be found at the Arduino Playground site.

Installing the Python modules

In Ubuntu, the getpass module should already be installed on you system and termios support compiled in (at least, it is on mine. I’m using Ubuntu 8.10.)

You can install the libgmail and serial Python modules in one go by opening up a Terminal window and issuing the following command:

sudo apt-get install python-serial python-libgmail

Installing Festival

In Ubuntu, just load up a Terminal and issue the following command to install the Festival Text To Speech package:

sudo apt-get install festival

Uploading the Sketch to the Arduino

First of all, connect the Arduino to your PC if you haven’t already done so, then execute the Arduino IDE.

When the Arduino IDE has loaded, check that the Board and Serial Port settings are correct for the setup you have. To check the Board setting, select Tools from the top menu then select the Board menu option and check that the name that’s currently selected matches the board you have. For example, my Arduino board is a Duemilanove, so I have the “Arduino Diecimila or Duemilanove” option selected here for my setup.

To check the serial port settings, select Tools from the top menu then select the Serial Port option. If your Arduino uses a USB port and you have no other USB-serial devices plugged in then /dev/ttyUSB0 should be OK here. Otherwise, use /dev/ttyUSB1 instead.

When you’ve configured your Board and serial options and everything checks out OK, it’s time to upload the Sketch to the Arduino. In the Arduino IDE, either use the Ctrl-O keyboard shortcut or select File from the top menu, then Sketchbook and then Open which should bring up the Open Processing Sketch window like the one in the screenshot below:

Open Processing Sketch Window. Click on image to open a full-sized version in a new browser window.

When this window is displayed, navigate to the directory where you unpacked the ardthermo source archive. From there, navigate to the sketch sub-directory, then to the thermometer. sub-directory. In the Files pane you should see thermometer.pde displayed. Click on this file to load the sketch into the IDE.

When the sketch has loaded, use the Ctrl-U keyboard shortcut or go to File, then select Upload to Board. If all went well you should see an LED on the Arduino blinking on and off once a second. This indicated that the sketch has been uploaded and has executed successfully.

About The Ardthermo Script

The Ardthermo script is a command line application and can operate in one of three basic modes:

Standard mode: Prints out a temperature reading (In degrees Celsius) and speak the temperature reading using Festival if its installed on the host system.
Email Listening Mode: Polls a configured email account for a valid command and send a temperature reading to the address the command originated from. A valid request email contains the text CMD:rtemp in the subject line. Any unread message with a valid subject line is treated as a new request and any text in the message body is ignored.
Email Alerts Mode: Monitor the temperature once every minute and send an email to a configured address if the temperature exceeds a threshold specified by the user.

When you first unpack the script, you will need to configure it. To do this, load the file ardthermo.py (this is the main program, all the other files you will see are modules and cannot be run directly!) into your preferred text editor and scroll down until you come across the configuration options.

There are 5 configuration options you will need to set, which are described below:

AlertsAddress: Used by the Email Alerts mode function: Specifies the recipient of alert messages.

FestivalPath: The path to the Festival program on your system.

GmailUser and GmailPass: The username and password of the gmail account that will be used by the Email Listening mode function for incoming requests and responses, as well as by the Email Alerts Mode function in order to send alert messages.

MailCheckDelay: Used by the Email Listening mode function: Specifies how often the configured gmail account should be checked for new incoming requests.

After setting the configuration options, you should also check that the ardthermo.py script has executable permissions. If it does not then issue the following command to enable them:

chmod +x ardthermo.py

Using Ardthermo

In order to run the script, you must supply the serial port the Arduino is connected to as the first argument, then the mode you wish to run it in as the second argument. For example, if you wanted to run ardthermo in Standard Mode and your Arduino was connected to the serial port device /dev/ttyUSB0, you would issue the following command:

ardthermo.py /dev/ttyUSB0 -t

To use Email Listening Mode, you would supply -e as the second command line argument. For Email Alerts Mode, you would supply -ea as a second argument and the trigger-point (or threshold) for the alert email message as a third argument. So, for example, if you wanted to be emailed when the temperature of a room reached or exceeded 20 Degrees Celsius, you would issue the following command:

ardthermo.py /dev/ttyUSB0 -ea 20.0

More details on the command line arguments needed to use the different modes of the script can be obtained by either running ardthermo.py with no additional arguments or by supplying the -h (help) argument on its own, which will print the help message to the terminal. You can also check the comments of the Ardthermo script and its companion modules for more guidance.

Limitations

This script does have a few limitations. For one, its not mult-threaded so you can only use one mode function at a time. Another big limitation is that it only reports the temperature readings in Celsius, with no option for readings to be given in Fahrenheit as well.

If there’s demand for it, I plan to write a multi-threaded version of Ardthermo with an option for Fahrenheit readings as well; If I can get my head around writing mult-threaded apps, that is! Oh, the “joys” of being a Python newbie

Until next time, have fun and happy coding/hacking/whatever floats your boat!