A few days ago an appeals court in the US has substantially reduced the amount
of patentable non-things: business-method patents were flushed down the drain. To-be-patented thingies
are to be scrutinised a lot more before a patent can be granted. Software gets harder to patent.
More on this quite interesting issue at groklaw.
[ published on Fri 14.11.2008 12:05 | filed in interests/anti
(Somewhat) apropos yesterday's article on tinkering:
I wanted a simple setup to mount my Treo phone/pda in the car. None
of the kludges for sale impressed me favourably,
all being expensive/clunky/both or worse.
Being the Dismantler and Recycler Of Crap that I am, I have a few
dead hard disks sitting around. Dead hard disk = two large and strong magnets,
iff you manage to get them off their backing
without breaking the brittle material. Sometimes I do manage, sometimes
So here's my ghetto mount: a fat magnet in heatshrink tubing, embedded in
the back of a slab of coreflute which is stickytaped
to the car dash. The Treo-side consists of a bit of thin sheet metal
(was once part of a floppy drive housing) taped to the back of the treo with
super-thin packing tape.
The hard disk magnet is easily strong enough to work through one layer
of heatshrink, coreflute, the silicon glove and the packing tape.
With the packing tape no irreversible mods to the Treo are necessary.
Simple, neat and zero-cost. I like that.
[ published on Tue 11.11.2008 12:26 | filed in interests/tinkering
It's Conny's laptop and I'll paint if she wants that.
Actually, she does, and not surprisingly, I did.
She wanted a skull and crossbones design and who am I to object to that
Sound Sensible Choice :-)
I found a tiny image on the web and used that as an inspiration to
come up with this design. Then I reused an old conference presentation
slide and cut that for a mask, and went shopping for paint: fluoro pink.
The mask I fixed to the lapdog lid with spray glue (sprayed onto
the mask, of course), and then I rattlecan-sprayed four layers: plastic primer,
a thin coat of silver as a lightening base and two layers of pink.
Removed the mask, cleaned the glue residue off and neatened some of the
spots where I had been too generous with the paint (raised edges).
The stupid pink paint decided not to be very fluorescent (even with the
silver base), but pink it is.
Another coat of gloss enamel for the whole lid is forthcoming, but Conny is
pleased with the result - and so am I.
[ published on Tue 11.11.2008 12:11 | filed in interests/tinkering
I just saw a really interesting article, titled
reflections on tinkering. Recommended.
[ published on Mon 10.11.2008 08:49 | filed in interests/tinkering
My newish Treo 680 has blue teeth, which is better than a kick
in selfsame (but not very much as shoddily as it was implemented by Palm). Being only a moderate
gadgeteer (and far from rich) I've been lusting after a
good/cheap/simple (yeah, I know RFC1925) navigation setup for the
car - and cable-less as much as possible.
So I got a cheap Bluetooth GPS receiver which is branded
"HP iPAQ Bluetooth GPS BTG-10H". Interestingly that model seems to have been orphaned by HP
and is now sold under the name Siraya. $20
for a new 12-channel receiver with data logging, some other goodies and a car charger;
not bad I think.
A bit of digging determined that it uses an iTrax03 GPS chip made by Fastrax, a Finnish company.
Now I don't know about Finnish attitudes towards the Dutch in general, but
this Finnish piece of electronic wizardry absolutely killed the Dutch fount
of navigational wisdom. (Apropos nothing in particular: the Dutch have a reputation as
lousy drivers all across the mountainous parts of Europe.)
Tomtom Navigator 6 works quite well - when it works at all. Specifically
Treos and Bluetooth receivers are well known sources of
horrible interoperability problems. Same here: my receiver gets
a fix moderately quickly and the TomTom shows the way, but after no more than 10 minutes
the TomTom locks up my Treo completely - until the GPS is switched off or
the BT connection is lost.
This obviously sucks, and is a tale of woe oft repeated
elsewhere on the intertubes.
I am, however, really stubborn about fixing problems. So I started digging
through all the horror stories, tried all kinds of suggested things, learned a bit
about NMEA, to no avail - until the really simple,
really stupid cause dawned on me: During a session
with a serial terminal reading the NMEA data from the iTrax I realized
that the volume of stuff it sends is quite..substantial.
The FasTrax docs about NMEA and their
chips are quite good.
NMEA has a bunch of required and optional messages, and I learned that for barebones navigation
one only needs RMC messages as often as possible;
if one also wants to know things like satellite positions and fix quality, one needs GSA and GSV.
Other GPSs seem to have configurable separate output rates for these messages; most tips I found
mentioned setting RMC to 1/sec and GSA/GSV to once every 5 secs - which makes a lot of sense,
because there will be multiple GSV messages depending on the number of satellites in view.
Not so with the iTrax: you can configure the output rate very precisely (up to 5Hz) but only one
rate for all messages - and by default it spews its (nonstandard) figure-of-merit message as well
as a full set of GSVs every second. At least on the Treo this overwhelms TomTom after a few
minutes (which sounds like very shoddy programming to me) and everything locks up hard.
The fix? Get rid of the GSV messages: you do lose
the per-satellite signal quality and azimuth/elevation info, but that's all.
The satellite status screen simply shows blank bars with the satellite number and
the GGA and GSA messages still tell the TomTom enough to know how many and which
satellites are in use and how good the nav fix is, so all is well.
FasTrax has made configuring the iTrax very simple: you send it
ascii (nonstandard-but-NMEA-formatted) commands over the serial/BT connection and it
stores them persistently in flash, done.
I used BT Serial on the Treo,
which works very well.
The online docs have all the necessary configuration info and
the only thing you'll actually have to do is send it this one message, once:
22 is the SYS_NMEA_MASK parameter, controlling which messages you want, and A002 means
"send only RMC, GGA and GSA". (The default mask is A023, which includes the above plus FOM and GSV.
$PFST,CONF,22 shows you the current value of that parameter.)
Wasn't that easy?
[ published on Tue 04.11.2008 23:00 | filed in brainfarts
So you have a nice, nifty RC car which is shiny and very fast
(and therefore cool) or dirty and really slow (and therefore cool) and
yet you are unhappy with its turning radius?
You might consider rigging it for four-wheel steering, which is very nice
for tight turns but not so much fun or stable for high-speed runs.
Which do you choose, stability and 2WS or tight turns and 4WS? Can't
one have both?
Indeed you can. Faced with this very challenge for my Wheely-King-based rock crawler,
I've built a four-wheel steering controller (4WSC) which gives you
that choice and lots more, provided that you have a radio with
one free channel: with that channel you can switch between proportional
four-wheel steering, two-wheel steering front or rear and
crabbing, on the go and without stopping. Your one steering wheel controls both
servos appropriately, based on your chosen mode of operation. The 4WSC also
includes a servo reversing cabability for your year servo and
is configured/programmed using your rc transmitter.
You might have a look at the manual to see what other goodies I managed to program in.
Here is what the 4WSC looks like: tiny (that's a 1cm grid) but
quite capable and cool.
As always with my stuff, it's open source software: the commented
source code is available right here for your perusal/modifications/other
weird applications. Share and Enjoy.
You might almost call the 4WSC an example of
"open source hardware": I'm also providing a printable
circuit board design, ready for making your own pcb's
with the toner transfer method.
The hardware side of the 4WSC is really simple: it is microcontroller-based,
uses a PIC12F635 or 12F683 or similar, and because PICs are great devices it
does not need any external components (except for plugs/leads and a buzzer).
All you need to build your own is such a microcontroller, a PIC programmer
interface for programming it, soldering gear and either some protoboard
or minimal PCB-making skills.
If that sounds too tedious/complicated, you can simply pay me
a little money and get one finished and ready:
I made a few of the controllers and am sufficiently happy with the outcome
to sell them. Contact me here and we can discuss the details; I might also do custom firmware for your
specific requirements (for a fee, mind you).
For the do-it-yourself afficionados (like me) here are the goodies:
[ published on Tue 04.11.2008 13:44 | filed in mystuff