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-lower-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
