&ot Journeys' End: April 2007

Journeys' End

We walk many paths, many roads
Till death halts our steps.
Every day a new adventure,
A new journey of self discovery.

20070429

PIC-PG2C

PIC-PG2C is a simple JDM serial FLASH programmer. It runs directly off the serial port, requiring no external power source. There is some concern it will not work with low power serial ports, such as those found on laptops. I am happy to report however that it works on an IBM Thinkpad T20.


Cheers,
Steve

Labels:

posted by steve @ 11:17 PM  

20070428

For those playing at home

It seems some friends of mine keep track of me through my blog... which seems weird in a way, but OK :-) So for those ppl, I currently have chicken pox but is otherwise well.


Cheers,
Steve

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posted by steve @ 1:40 AM  

20070414

Writing fitting functions for lmfit

lmfit expects fitting functions with prototypes in the form:

double function_name(double, double *);

For example:

double sin_fit(double t, double * p)
{
return p[0] + p[1] * sin ( 2 * M_PI * ( p[2] * t + p[3]));
}

Note that while lm_minimize takes a pointer to an array of parameters, it may not always pass that pointer to the fitting function. Because of this passing fixed parameters to the fitting function using the 3rd argument will yield incorrect results. For example, the following code is wrong:

double wrong_fit(double t, double *p)
{
return p[0]*p[0] + p[1];
}

....

double p[2];

p[0] = 1;
p[1] = magic_number;

...

lm_minimize(..., 1, p, ..., ..., ...., ...);

Here the fitting function wrong_fit relies on a fixed parameter p[1] which it expects to contain the value magic_number. However it will be passed such a p that only p[0] has a valid value and p[1] is undefined. This will lead to incorrect operation.

To work around this, you can use global variables, as follows:

double magic = magic_number;

...

double right_fit(double t, double * p)
{
return p[0]*p[0] + magic;
}

....

double p = 1;

...

lm_minimize(..., 1, &p, ..., ..., ..., ...);

Cheers,
Steve

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posted by steve @ 11:27 PM  

20070406

PIC Programming under Linux with KIT81

To get KIT81 and its variants working under linux, you need picprg, and configure it as follows:

PinPolarity
Vpp-
Vdd-
Clock+
Data out+
Data in+

The following screen shot shows what the configuration screen should look like:


Cheers,
Steve

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posted by steve @ 7:24 PM  

asciigrams

asciigram: n.

A relative of the emoticon, an asciigram is an upright diagram of a gesture or body language construct using ascii characters.

Currently the following are somewhat popular:

\o/hands in the air
\o>salute
<o>hands behind/above head, surrender

Cheers, Steve

posted by steve @ 12:23 PM  

Defending Others

Any people that would beat or kill you for insulting someone are not enlightened, cultural superiors. They simple zealous lunatics.
Cheers, Steve

posted by steve @ 1:24 AM  

20070402

CAT

Emacs and Vi are too bloated. If you must use a utility to compose text files in unix, there is a perfectly usable and full featured word processor right there in /bin on every POSIX compliant system. I speak of the Computer Aided Text processor It has a few command line options depending on whether you want your lines numbered, reduce unnecessary whitespace, and other conveniences. Each line is fully editable until you commit it by hitting the enter key. If something happens while you're typing it, not to worry: it autosaves after each line of text. Just use the -a (append) option when you run it again to finish the file. You only need to remember one control sequence. Unlike those wannabe window managers like emacs and vi with their scores of non-mnemonic commands. When you're done typing in cat, hit ctrl-d (for done, of course) and that's it.
Cheers, Steve

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posted by steve @ 1:45 AM