DFT Computation time at 16 MIPS
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From: Vince on 12 Mar 2010 07:36 I'm processing a 1-D DFT at 16 MIPS and I'm trying to find out my computation time. How do I do this? Any help would be great.
From: Jerry Avins on 12 Mar 2010 09:00 Vince wrote: > I'm processing a 1-D DFT at 16 MIPS and I'm trying to find out my > computation time. How do I do this? Any help would be great. Measure it? Jerry -- Why am I in a hand basket? Where are we going? �����������������������������������������������������������������������
From: Vladimir Vassilevsky on 12 Mar 2010 10:26 Vince wrote: > I'm processing a 1-D DFT at 16 MIPS and I'm trying to find out my > computation time. How do I do this? Any help would be great. There is a thing which they call a "clock"; it is very useful if you need to know when to do something. VLV
From: Nicholas Kinar on 12 Mar 2010 10:52 On 12/03/2010 6:36 AM, Vince wrote: > I'm processing a 1-D DFT at 16 MIPS and I'm trying to find out my > computation time. How do I do this? Any help would be great. > > To elaborate on this discussion: (1) Your microcontroller should have a timer which can be triggered immediately before the computation and stopped immediately after the computation. Then print the output of the timer to a spare serial port of your microcontroller. Usually on a prototype system, the spare serial port could be connected to a RS-232 level shifter, so you can view the results on your computer using terminal emulation software (i.e TerraTerm). (2) Toggle an LED attached to a port pin of your microcontroller. (For example, turn on the LED immediately before the calculation begins, and turn it off immediately after the calculation.) Measure the time with a stopwatch for a rough estimate. This may be more appropriate if the input data is a very long sequence. (3) Toggle the level of a port pin, and use a logic analyzer to find the time taken for the calculation. (4) If your embedded system runs some form of operating system such as Linux or uCLinux, use the OS time functions to measure elapsed time. HTH
From: Rob Gaddi on 12 Mar 2010 12:22
On Fri, 12 Mar 2010 06:36:24 -0600 "Vince" <vpriolo(a)strasbaugh.com> wrote: > I'm processing a 1-D DFT at 16 MIPS and I'm trying to find out my > computation time. How do I do this? Any help would be great. > I'll add to everyone else's comments the fact that you haven't specified the number of points you're working with. Given that, if my memory's not totally shot, the dumb DFT is O(N^2) and that the FFT is O(N log N), do keep in mind that your computation time will be a strong function of N, i.e. size matters. -- Rob Gaddi, Highland Technology Email address is currently out of order |