Post by thread:MOMA-filter field observation & speed up idea

I just configured my app to generate high level on a pin during execution of MOMA. Then set up an Oscope to trig on rising edge so I could watch ececution time in real application. Execution time varies much because of the filters first part which searches for the first array value < seed, as it starts searching from the top max of the array. Studying the pulse time then give a good idea of where in the array the new value is injected = what the new value is in relative to the current max-min range! @ 20MHz, execution time varies between approx 100µs (rising feed values) to 180 µs (falling feed values). Code used: as posted but she sum routine corrected and speeded-up using the known zero register trick (also giving the add constant execution time), and the div8 speeded to 9 cycles (9 rrf). What i learned from watching the Oscope is that when the sensor signal is stable, and only noise actually controls where new values are injected; is that the most values are injected in the top and bottom ends of the filter. In my app approx only 1/20 of them (looked like; very approximately) were injected in the 8 median values (which are used for calculating output) The filter can therefor be speeded up if the scan-for-adjacent-values routine first checks if input is higher or lower than the filter median, and then start the search from the relevant end, towards center. The execution time would then most often be close to 100µs (injected close to array ends), or maximum slightly above 140µs. I don't need this speedup, but if anybody constructs such a routine, i would be happy to recieve it. :) Regards /Morgan Morgan Olsson ph +46(0)414 70741 MORGANS REGLERTEKNIK fax +46(0)414 70331 H€LLEKS (in A-Z letters: "HALLEKAS") SE-277 35 KIVIK, SWEDEN spam_OUTmrtTakeThisOuTiname.com ___________________________________________________________

Hi Morgan, > The filter can therefor be speeded up if the scan-for-adjacent-values > routine first checks if input is higher or lower than the filter median, > and then start the search from the relevant end, towards center. My Idea how to speed up the search is: new_input := tyngd_in size := size_of(viktfilter_array) rrf size; ; half array movf size, w movwf FSR loop movef INDF, W rrf size ; quarter array IS W > new_input add size to fsr else sub size from fsr if W = new_input or size = 0 fsr contains address where to inject new input else goto loop or to try this in a more textual way: if you test for higher or lower the value in the middle, then you know in which half the value has to be. now test higher or lower in the middle of the appropriate half. gives you the quarter where the value will be, now devide the quarter in two segmemts again checking for higher or lower until you4re just have two values left where the new value can be between. gives you the address where to inject. sorry for the pseudeo code but the Idea came very recently into my mind. I also think there is a quite better way to describe this algorithm. It4s like descending a binary tree. kind regards Stefan Sczekalla-Waldschmidt .....sswKILLspam@spam@oikossw.de