Lpc2000

Hi Rolf, 

> Hi Paul,
> 
> thanks for reply.
> 
> ----- Original Message -----
> From: Paul Curtis
> To: lpc2000@yahoogroups.com
> Sent: Friday, March 11, 2005 1:05 PM
> Subject: RE: [lpc2000] 2d linear Interpolation
> 
> > Rolf,
> 
> > ...but this is a classic problem, such as interpolation of 
> ECU mapping 
> > parameters like engine speed against manifold pressure.  
> It's only a 
> > very simple piece of maths, what is the problem?  From what 
> I see on 
> > the GIF, the calculations are all laid out for you.  Hence, 
> I conclude 
> > it's a homework assignment and you'll never get anywhere if 
> others do 
> > your homework.
> 
> Yes, you are right. It is simple for me with paper and 
> pencil. But is much harder, to code it to C. I just started 
> with C. Is it so awfully, to ask for prepared source?
> I am not a lazy bone, the most of my free time is going in 
> self study for electronic and programing. Excuse me, if my 
> question had made you angry. 
> This was not my goal. Please dont take offence for me. And 
> excuse my english, it is self-learned, too. ;-)

I have absolutely no problem with people asking for help, but 2D
interpolation as I said is a classic problem.  There are some
processors, for instance, that have instruction for table lookupand
interpolation such as the CPU32 (TBLU).  I'd rather you looked at the
maths that is behind this.  2D interpolation is simply two 1D
interpolations, one along the X axis and then one along the Y axis (or
the other was round if you wish).

A 1D interpolation is simple, because you can figure out rise and run
between two points in the table (or, as Al points out, you might already
have that calculated)--but usually, when I was working on the software
for an ECU, the maps were changed in the ECU during runtime to see what
happens.  Given the slope, you can easily interpolate the value at a
point between them.

This is basic stuff that you should have learnt before your school
leaving exams.  In fact, you should have learnt curve fitting and things
such as linear regression too?

--
Paul Curtis, Rowley Associates Ltd  http://www.rowley.co.uk
CrossWorks for MSP430, ARM, AVR and (soon) MAXQ processors