>On Tuesday 25 August 2015 09:19:15 Marius Liebenberg wrote: > >> Thanks all for the help. I used a Teensy 3.0 bord from the drawer and >> it works great. I am reading a 2khz signal from the parport and >> converting it to a 40khz signal. Duty cycle is from 0% to 99%. > >And this is what I love about this list. I have long since given up >trying to count how many ways a cat can be skinned. So the education >continues apace. I would not have thought of that because I didn't >have >a suitable bit of hardware laying around. > >I have to give credit where inguinuity (my speal cheeker fails this >one) >solves the problem in an unusual way that makes perfect sense. > >Deserves a tip of the hat. > >Thanks Marius. >
Dont know how much is intuitive and how much is "in trouble". Man must do what a man must do :) I am busy building a massive laser cutting machine for a customer and I am a bit late as per usual. Now I discover the quirks of integrating unknown parts. >> >I have not checked the AVR but most micro controllers have timers >> > with hardware support or duty cycle measurement. XMC4xxx or STM334 >> > devopment boards have high resolution timers equal to a frequency >> > about a few gigahertz. >> > >> > >> >On Tue, 25 Aug 2015 21:09:08 +1000 >> > >> >Erik Christiansen <[email protected]> wrote: >> >> On 25.08.15 10:30, Marius Liebenberg wrote: >> >> > I have a couple of Teensy 3.0 boards in the drawer here and >>they >> >> >> >>are >> >> >> >> > pretty fast enough I think. >> >> > I am a bit allergic to the USB interface when one uses high >> >> > current switching devices on the machine. The USB interface is >> >> > not that reliable. >> >> >> >> It would not be hard to use one Arduino timer in capture mode to >> >>measure >> >> M/S ratio of a low frequency PWM input (from LinuxCNC), then >> >>replicate >> >> the ratio on a higher frequency output on another timer. If the >> >> ratio of >> >> input and output frequencies were a binary multiple, then >>dividing >> >>the >> >> input mark to fit the higher frequency output would only be a >> >> right shift of the requisite number of bits. (The AVR does not >>have >> >> hardware >> >> multiply, but software multiply would be OK, if preferred, if the >> >> PWM ratio doesn't change at a crazy high rate.) >> >> >> >> An interrupt on "capture complete" would be infinitely more >> >> efficient than any polling hack, for input PWM measurement. The >> >> output timer would >> >> just run with auto-reload, responding to a new M/S ratio in the >> >> next cycle >> >> after it is written to the hardware register. >> >> >> >> A 20 MHz part could run 10 bits of count at 20 kHz, giving 0.1% >> >> resolution. Go for something like 9 bits, 40 kHz, and 0.2%, >>maybe? >> >> >> >> But mebbe you have all that figured, already. >> >> >> >> Erik >> >> >> >> -- >> >> Since late last year, Saudi Arabia has been flooding the world >> >> with cheap oil in >> >> an attempt to squeeze the life out of America's nascent shale oil >> >>industry, >> >> sending crude to six-year lows around $US40 a barrel. >> >> - >> >> >>http://www.abc.net.au/news/2015-08-20/qantas-profit-propelled-by-low >> >>er-fuel-prices/6711174 >> >> >> >> >> >> >>-------------------------------------------------------------------- >> >>---------- _______________________________________________ >> >> Emc-users mailing list >> >> [email protected] >> >> https://lists.sourceforge.net/lists/listinfo/emc-users >> > >> >> >--------------------------------------------------------------------- >> >--------- _______________________________________________ >> >Emc-users mailing list >> >[email protected] >> >https://lists.sourceforge.net/lists/listinfo/emc-users > > >Cheers, Gene Heskett >-- >"There are four boxes to be used in defense of liberty: > soap, ballot, jury, and ammo. Please use in that order." >-Ed Howdershelt (Author) >Genes Web page <http://geneslinuxbox.net:6309/gene> > >------------------------------------------------------------------------------ >_______________________________________________ >Emc-users mailing list >[email protected] >https://lists.sourceforge.net/lists/listinfo/emc-users ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
