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From: email@example.com (Frank Miles)
Subject: Re: Trig circuits
Date: 23 Dec 2002 17:59:11 GMT
Organization: University of Washington, Seattle
In article ,
John Jardine wrote:
>Spehro Pefhany wrote in message
>> On Mon, 23 Dec 2002 14:11:47 -0000, the renowned "John Jardine"
>> Here is the step-by-step procedure:
>> 1) BUY a decent COMPILER
>> 2) Type in the EQUATIONS- use double and #include math.h for
>> trig (if using C)
>> 3) RELAX and have a nice cold BEER (or a warm one if you'd
>> prefer) It will work just as it worked on your PC.
>> There is NO need to devote hardware to this- the chip described is
>> a pre-programmed microcontroller aimed at a non-professional
>> market IM(NS)HO. A $5 US chip can burn 50% of its bandwidth
>> (say 4MIPS) running floating point math in the background
>> while walking and chewing gum with every port pin. It's a no-
>> brainer, guys.
>> Best regards,
>> Spehro Pefhany
>> "it's the network..." "The Journey is the reward"
>> firstname.lastname@example.org Info for manufacturers:
>> Embedded software/hardware/analog Info for designers:
>Sounds like those compiler things can make life nice and easy ;-) The ones
>I've come across (for the smaller micros anyway) always seem to have some
>resriction on the precision and range of the maths functions. Eg, floating
>point not available, just integer maths and even then only to say 32 bits.
>Trig and Log functions are sometimes added just as an afterthought, offering
>say 1% integer accuracy (I can do better myself). I agree and would expect
>the more expensive compilers (C or Basic) should offer maths routines at
>least equiv to a calculator. There is always the downside though that the
>compiler may come across say "sin(a)" and all of a sudden an internal 2K of
>micro programme memory disappears. (you noted it yourself ;-).
>What I'm getting at here, is that yes, for the more full blown larger
>projects it becomes worthwhile to buy a larger micro with larger prog'
>memory with the intent in the first place of using a rather pricey compiler.
>The job is worth it and the development time is reduced greatly.
>But, for the smaller, cost sensitive high volume jobs (say an angle sensor
>to use a 1k or less PIC)), using a compiler will give impossible space and
>efficiency problems and hand coding is still needed. An add-on chip (if
>cheap enough) could provide the 'Sin' answers with no overhead on the main
>micro and a possible final cost reduction.
>Someday I'll experience the pleasure of using a good compiler. I'm a bit of
>a hair shirt masochist at the mo' ;-)
Look-up tables (possibly with some simple interpolation) can be your friend.
And if you really have a high-volume job, you can afford a spiffy compiler.
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