Python Programming for Nokia N95: A Beginner's Guide - Prof. Timothy W. Bretl, Study notes of Aerospace Engineering

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Lecture 1

Symbian/Python Basics

Tim Bretl

Department of Aerospace Engineering

Beckman Institute for Advanced Science and Technology

University of Illinois at Urbana-Champaign

AE498MPA

August 29, 2007

Some facts about the Nokia N

• (^) Symbian OS
• (^) 332 MHz CPU
• (^) 64 MB RAM
• (^) 160 MB internal memory + microSD memory card
• (^) 240x320 color screen
• (^) GSM 850/900/1800/1900 MHz + GPRS
• (^) Hardware accelerated 3D graphics (OpenGL ES)
• (^) Two cameras (5 megapixel)
• (^) Internal, fully-functional GPS (1 Hz)
• (^) Bluetooth, wifi, infrared, fm radio, mp3 player, audio recorder, ... , and also a phone

Why Python?

• (^) It is an object-oriented programming language that supports integration with Java

and C/C++, has extensive standard libraries, and is easy to learn.

• (^) It is open-source (download for your PC from here) and cross-platform, although

extensions are often specific to particular hardware or operating systems.

• (^) The syntax is simple, so code is typically 1/3 to 1/5 the size of Java/C++.
• (^) Any text editor can be used to create python scripts. No compiler is required (you

only need a python interpreter, similar to MATLAB). Try to get a text editor that does

syntax highlighting, like ConTEXT, Emacs/XEmacs, or TextWrangler (a.k.a. a poor

man’s “BBEdit” on a mac).

• (^) It is supported by Nokia with the port “Python for S60” (PyS60). This port provides

extensions that access most of the phone’s important features (camera, contacts,

calendar, audio input/output, TCP/IP, bluetooth, telephony, GPS, etc.). In fact, the

folks at Nokia use python for their own research and product development.

Why not Python?

• (^) As an interpreted language, execution speed is not always so fast as compiled

languages like Java or C/C++.

• (^) MATLAB has the same drawback, by the way.
• (^) But... it is much easier to use than C/C++ (which is very weird for Symbian OS) and,

through extensions, has more access to the phone’s features than Java.

A quick way to test your installation

• (^) In the python interpreter (on the phone), select Options->Interactive Console.
• (^) Turn off the dictionary (essentially word completion) by typing # twice.
• (^) Then use your keypad to enter our favorite command:

>>> print “Hello, world!”

• (^) You can do everything directly on the phone in this way, if you want. But it will be

more productive to (1) use scripts, and (2) use a bluetooth console.

Using scripts

• (^) In a text editor on your PC, create a file called “helloworld.py” with the following

lines:

• (^) Transfer this file to E:/Python/.
• (^) In the python interpreter, do Option->Run Script, and choose helloworld.py from the

list. You should see the alert, then the result (should be 1.38) of math in the console.

• (^) This is an example of running a script. (Like an m-file in MATLAB.)

  import the user interface module

  import appuifw

  create an alert (shows up in the UI)

  appuifw.note(u"Hello, world!","info")

  do some math (shows up in the console)

  print (1.2+2.3+3.4)/

Some syntax examples (numbers, strings)

• (^) Numbers
• (^) Strings

>>> int(2.6) 2 >>> s='hello' >>> s 'hello' >>> print s hello >>> print s,'world!' hello world! >>> print s+'world!' helloworld! >>> s[1] 'e' >>> s[-1] 'o' >>> s* 'hellohellohello'

Some syntax examples (lists)

• (^) Lists (think of them as lists of objects) >>> list=[1,2,3] >>> list [1, 2, 3] >>> list[0] 1 >>> list.append(4) >>> list [1, 2, 3, 4] >>> list.append('string') >>> list.append(['firstitem','seconditem']) >>> list [1, 2, 3, 4, 'string', ['firstitem', 'seconditem']] >>> list.pop() ['firstitem', 'seconditem'] >>> list [1, 2, 3, 4, 'string'] >>> list.pop(0) 1 >>> list [2, 3, 4, 'string']

Some syntax examples (if/else, for)

• (^) If/else (note the colon and the indent, and note the lack of semi-colons)
• (^) For (note we can iterate over elements of a list) >>> name='tim' >>> if name=='andrea': ... print 'Same name!' ... else: ... print 'Different name!' ... Different name! >>> for i in range(0,5): ... print i ... 0 1 2 3 4 >>> list [2, 3, 4, 'string'] >>> for i in list: ... print i ... 2 3 4 string

Some syntax examples (while, functions)

• (^) While

• (^) Functions (think of these, too, as objects) >>> i= >>> while i<4: ... print i ... i=i+ ... 1 2 3 >>> def f(n): ... print 2*n ... >>> f(5) 10 >>> f('tim') timtim >>> f

  &gt;&gt;&gt; g=f &gt;&gt;&gt; g &gt;&gt;&gt; g('andrea') andreaandrea

More information

• (^) For the standard library and basic syntax, see the documentation from python.org.

In particular, you should go through the tutorial (or at least parts of it) before next

class. This should not take you more than about 2 hours.

• (^) For the pyS60 phone API, download PythonFoS60_1_4_0_doc.pdf from the

sourceforge site. (Make sure you get the right version of the documentation.)

• (^) Also see the Nokia opensource site.
• (^) Also see this tutorial, which is filled with examples.
• (^) If you want a book, try Learning Python.
• (^) The python for s60 discussion board may also be helpful. Yes, people do respond

to your questions fairly quickly, in most cases.

Emulator

• (^) It is possible to test and debug code on your PC only.
• (^) I don’t necessarily recommend this, since the setup process is not trivial, since what

you get is really a “simulator” and not an “emulator,” and since certain key elements

of the phone (camera, GPS, etc.) are not simulated.

• (^) Moreover, a lot of your syntax can be tested/debugged just by running python on

your PC (eliminating calls to the phone API, of course).

• (^) And of course, by using a bluetooth console, you have a lot of the benefits of PC

testing while actually running things on the phone.

• (^) But if you are using a windows machine and are gung-ho...

An important note

• (^) Symbian OS is fairly open to developers. It does this by using a special certification

system, called “Symbian Signed”. The *.sis files that you install on the phone are all

signed using this system. If you install something that is unsigned, or that is “self-

signed”, you won’t have access to all of the phone’s features.

• (^) Currently, we are unable to register new accounts with the Symbian Signed website,

hence cannot certify the Python installations on our own phones.

• (^) Consequently, we don’t have access yet to certain key modules, such as the GPS

(positioning) module.

• (^) Don’t worry, I am working to correct this problem.
• (^) In the meantime, we have access to a LOT of other stuff, including the camera,

bluetooth, file input/output, the user interface, etc.

Acknowledgments

• (^) Some of the material for these notes was taken from the following sources:
  • (^) Vidya Setlur, Nokia Research Center (Palo Alto)
  • (^) Larry Rudolph, MIT
  • (^) Nathan Eagle, MIT