Technical Ramblings

So, today, I built a small application to demonstrate the use of the accelerometer built into the Nokia N95. I decided to convert a simple example: the ‘ball.py’ example that ships with Nokia’s distribution of Python for Series 60 (SourceForge).

The ball.py example uses the arrow keys to move a ball around the screen. Instead, I wanted to tilt the screen to do it.

The result came out reasonably well: I even used the webcam on the eeepc to put together a little video:

The code is available from my Symbian page, which has received so few changes that it doesn’t actually even mention my 6600 that I got years ago, and have since upgraded from.

In my searches, I wasn’t able to find a lot of source code for pure-Python scripting using the accelerometer, so hopefully if anyone is looking for demos of accelerometer usage, they can take this as an example in Python.

Love to hear any feedback if anyone else gives it a shot…

If you have a Macbook, and at some point, you get “Bluetooth not available” from your laptop, and “No information found” in your System Information app for Bluetooth, it might help if you try to reset the Macbook SMC, as described in Resetting MacBook and MacBook Pro System Management Controller (SMC). I had this problem for the past couple days, and doing this fixed it for me.

(This article is largely published so that others searching for “Bluetooth Not Available” may be able to find it before taking their Mac into the shop.)

Note to self:

The NMEA\_to\_DecDeg function is documented in Mapping Hacks, hack #62, “Build a Car Computer”.

(I’m going to be working quite a bit on my gsmlocation stuff in the next couple weeks, building up to a lightning talk presentation at Where 2.0 on June 13th. If you have a Bluetooth GPS and a Series 60 Symbian cell phone, please talk to me: I could use your help in building up a larger dataset.)

One of my biggest problems so far in my writing of mobile software is that I don’t have any form of regular communication with the users of these applications. Support queries, questions, etc. get posted in blogs and so on that I never read, feedback is posted to wikis I never use, or worse, it goes into email and conversations are lost forever.

In a possibly misguided attempt to fix this, I’ve set up a Symbian Hacks mailing list. This mailing list is designed to serve as a feedback mechanism for the code that I’ve written for the mobile platform, and hopefully will encourage me to give back to the community in more meaningful ways.

If you’ve ever used something I’ve written on your phone, please join the list and just send an email saying “I used $foo and I loved it!” You will really make my day.

Today, there are a large number of cheap bluetooth GPS devices on the market. These devices allow you to connect to the device wirelessly, which is great for when you’re driving and don’t want cables draped all over the car.

However, what happens when you can’t drag your computer out to act as a display of your position? No bluetooth GPS on the market today for under $500 has a display of any kind. When you consider that these things can be had for $70, that makes purchasing one go from likely, to ridiculous. What’s the point of a handheld, easy to use GPS if you can’t use it to see where you are?

If you’ve been asking this question, I’ve got software which has an answer for you. GPSDisplay will allow you to connect to NMEA compatible Bluetooth GPS devices and display your position fix. It is written entirely in Python, using NMEA code from Forum Nokia. It requires only that you first install Python for Series 60 on your device, and should work on all first and second generation Series 60 phones. Simply download the .sis file, send it to your phone, and you’ll be all set to go — you can use your phone as a display for that new cheap Bluetooth GPS you bought, and stop dragging your laptop out into the woods to go Geocaching.

I’m prepping my first actual .sis file release for the Symbian platform today. I’ve actually been doing it for the past couple days, but today is when I’m going to put in the brunt of the effort.

Most people don’t realize that for me, a release is a process, similar to the way any software company would do it. Prior to a release, I do many things, like checking in code to a revision control system, creating a webpage for the application, gathering screenshots, writing instructions and simple informational blurbs on a product, and so on.

It also leads up to me doing a markeitng blitz for the “product”, even if it’s free: doing my best to inform the persons who would be most interested in the newly released product that it is available. This includes posting in weblog, listing in IRC channels, etc.

Really, to create a full release, it takes me about a half day to get code from “Working on my phone” to the condition where I want to declare a release point, with ample documentation of what I’ve done, why I’ve done it, and why I think it might be useful.

This is going to be my first release using some new tools: specifically Py2SisNG, an *excellent* tool for creating .sis files out of Python applications. The documentation for the app is very good, and if you read the README in the distribution, it really does tell you step by step everything you need to do. I can’t thank the creators of this application enough. It has allowed me to turn my amatuerish Python script into an actual application, something I thought I’d never be able to do on a non-Windows platform.

Of course, there is still one limitation to what I can do: I can’t figure out how to create a .mbm image for the icon of the application. It seems like this little-used format is popular in the mobile world for storing multiple bitmaps in one file, but that there is little information on how to create these images under non-Windows platforms. I’m not sure if I’m going to delay the release until I have an icon for the application, but I’m considering it.

If anyone has any experience in creating .mbm images under non-Windows platforms, please let me know! I’d love to be able to put an icon onto my application to make it look just a little more complete.

In my spare time (hah!) I’ve been hacking on an app on Ning, called PeopleFinder. The goal is to be a geolocation app, supporting a variety of things social. One of my many goals for a long time has been to create and use some kind of tool which allows me to generate MeNow data with no effort.

I’ve finally got it.

With the help of Geocoder, I can now type in an address, and have it automatically update my location on the website, including showing my position on a GMaps interface. The PeopleFinder API is still a bit weak, but using it, I can write a Client for Series 60 Python, which allows you to update via a GPS lat and long, or via an address.

I’ve created a token system for authentication via the API — when logged in, you simply hit the token link, grab the token, and put it into the client (in the “token” variable).

Eventually, once I write the functionality, it is my hope that I will be able to provide more features via this API — the ability to look for people nearby you, get their information, send them messages, and so on. However, right now this is just a 2-3 hour hack, and I’ve got piles of work to do - but this is so cool I had to share it.

As far as I know, this is the first example of a Ning App exporting a semi-usable API to remote clients. In part, this may be due to previous limitations on Ning’s end which have recently been resolved: looking at the phone client code, you’ll see the ?xn_auth=no parameter, which allows you to skip cookie authentication. It’s a pretty nice solution to the problem in my opinion — it solves what I need while not interfering with the rest of Ning.

So grab your phone, grab a client, and update your address on the go — then, the next time I see you in the neighborhood, I’ll drop by and give you a wave.

crschmidt.net now features a new colorscheme: I’m still not sure how much I like it, but the old black/grey/white scheme was really starting to grate on me. (Note that the weblog uses a different stylesheet which I haven’t updated yet.)

Additionally, all pages now have a feature to allow commenting from users. So you can now leave a comment on any page! This is taken from Eikeon’s websites, which have this feature (although it requires logging in first). I’ve done some very basic escaping of script tags, and I do my best to add newlines if they are appropriate, but if you want to make your content look right, you’re best off just formatting it with HTML yourself.

However, this means that it’s really easy to offer feedback on any page of the site now. If you’re interested in my semantic web tools, you can leave comments on the various ones there. You can comment on the code for any of my Python tools, on my symbian stuff, on pretty much anything. Soon, and very soon, I’ll be writing an RSS feed generator for this. Right now I’m just happy it works, and would love to see people commenting on any page on the site they’d like more info about or would like to offer feedback on.

For those of you who are not yet aware, I will be in San Francisco this weekend, arriving Thursday night (late) and leaving Early Sunday afternoon. I will be in meetings all day on Friday, but if anyone is interested in meeting up, let me know.

People I plan to see so far include, but are not neccesarily limited to: Neil, twid, leora, miker and wombatmobile (possibly) from #mobitopia. I plan to visit tourist sites, as well as stopping by The Mothership in Cupertino while I’m there. I want to ride the famous Trolley’s, I want to eat tacos in the Mission district, I want to visit Unicorn Precinct XIII (note to self, poke zool to fix sf.openguides).

What else should I be doing? Should I go to the DNA Lounge? Muir Woods Redwoods?

Advise me, dear reader, as to what you would do if you were in San Francisco for 36 hours with nothing else on your todo list! Tell me if you want to meet me, and talk about the next hack for the Semantic Web! Tell me if you want to meet me and berate me for not working on location based cell phone computing! Tell me your thoughts on my work, tell me what you’d like to cook up next. Point me out the coolest things in and around downtown San Francisco, and come with me to see them.

The rest is up to you.

Matt Croyden mentioned the other day that there is a new Python for Series 60 Alpha release. Reading through Erik Smartt’s post on the topic, I realized that this offers a number of the features that I had wanted built in in the original release: Camera access, Address Book and Contact APIs, and other similar things.

I had put off working on Symbian Python work for a while, but with the new release, I think I’m going to put some more effort into it: use of the new APIs will make things easier (like automatically uploading pictures taken to flickr, one of my original goals) and makes me want to get hacking again.

Congratulations to the Python-on-Symbian team, and I’m looking forward to starting work with the new alpha release.