Re: Basic info needed regarding filters (FIR)

On Nov 24, 10:39 am, John Larkin
<jjlar...@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
On Sat, 24 Nov 2007 11:41:08 -0600, Vladimir Vassilevsky



<antispam_bo...@xxxxxxxxxxx> wrote:

John Larkin wrote:

On Fri, 23 Nov 2007 12:43:10 -0600, Vladimir Vassilevsky
<antispam_bo...@xxxxxxxxxxx> wrote:

Here is the basic realpole filter which is simpler and appears to have
almost identical response:

const u8 order = 4;

s32 LPF(s32 x)
{
static s32 z[order];

for(u8 i = 0; i < order; i++) x = z[i]+= (x - z[i])>>6;

return x;
}

Making digital filter as the simulation of an analog filter is rarely a
good idea.

I've sold over 3000 of the temperature controllers that use this
filter.

McDonalds serves somewhat 10 billion meals per year. But this fact doesn't
make those meals taste any better or worse :)

Selling things for high prices to high-end customers, in volume, for
years, bug-free, means we're doing exactly what we want to do. Any
other criterion for engineering quality is, literally, academic.

Why whining about the Evil Empire of Bill Gates then?

Because it's slow, bloated, and bug-ridden, from a company run by
sociopaths who crush competition out of sheer ruthlessness.

I am sorry if you didn't understand 3 lines of trivial C code without
comments. It would be a good idea to do some learning before suggesting the
advanced digital filter topologies...

I've made a solemn vow to never code in C.

Yes. C++ is lot better.

Funny! I write apps that run in, typically, 4-6 kilobytes of eprom and
2K of ram, manage a few FPGAs and a VME or serial/ethernet interface,
run thousands of interrupts per second, and have guaranteed response
times in the 100 usec sort of range, 100% of the time. And never
crash.



But comments don't explain
code, comments explain what code is for and what it does. Your filter
is just a heap of code. I have no idea what it's response is like, and
would have to analyze or simulate it to determine that.
So, what is its frequency response?

Here:

1/64
H(Z) = (---------------) ^ 4
63
1 - --- Z^-1
64

So, what is its frequency response?

John

I suppose you could use the bilnear transform to map it into the S
domain, then do a spread*** to see the response.

Learning basic C isn't that difficult. The object oriented flavor is
another story.




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