On Thursday 03 October 2019 10:17:01 Peter C. Wallace wrote: > On Thu, 3 Oct 2019, Gene Heskett wrote: > > Date: Thu, 3 Oct 2019 10:08:00 -0400 > > From: Gene Heskett <[email protected]> > > Reply-To: "Enhanced Machine Controller (EMC)" > > <[email protected]> > > To: [email protected] > > Subject: Re: [Emc-users] Real-Time Linux on the Raspberry Pi > > > > On Thursday 03 October 2019 08:25:10 Thomas J Powderly wrote: > >> Hi Gene, PCW, > >> I just hooked up a second ethernet port to an rpi3b. > >> I ssh'd into eth1 and ran a sim axis. > >> pi@raspberrypi:~/linuxcnc-dev $ uname -a > >> Linux raspberrypi 4.14.59-rt37-v7+ #1 SMP PREEMPT RT Sun Aug 26 > >> 15:11:25 +07 2018 armv7l GNU/Linux > >> > >> What tests can be run to see if this can use 'normal' mesa ethernet > >> cards? without actually having them ? > >> tomp > >> > >> The 'trick' to extra ethernet port without using the usb bridge > >> is to use an ENC28J60 module connected to gpio pins ( no usb > >> involved ) the ethernet is bitbanged spi > >> here's a link to what i did ( altho i have different pins used and > >> a slightly different module than he used ) > >> https://www.instructables.com/id/Super-Cheap-Ethernet-for-the-Raspb > >>err y-Pi > > > > Thats cute. But I see 2 potential problems. > > 1. Its half duplex, is this compatible with mesa ethernet driven > > cards? 2. its using the same signal lines the first spi port > > (hm2_rpspi.ko) uses. > > > > It can likely be moved of course but will need bootup options to do > > it I expect. Theres a discussion about spi on the pi3, and on the > > pi4, but I don't have the links handy. I think the pi3 has 2 > > independent spi's with two slaves on each, AIUI, the pi4 has more cs > > lines allowing more hardware to be addressed on a shared circuit > > basis. > > > > 3. And two last questions, how fast is it? (Went back to link, 10 > > megabit, not really fast enough for a mesa card) and is it > > reverseable? Eg, can it be used as a pair, driving the older 7i90 > > card over a longer cat5 link cable? An spi to spi link IOW? No. Not > > fast enough. My currently working spi is running 4.2x faster than > > that. > > > > Now if a 100 meg or even a gigabit version could be had... > > Interesting idea. > > > > 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) > > If we desire respect for the law, we must first make the law > > respectable. - Louis D. Brandeis > > Genes Web page <http://geneslinuxbox.net:6309/gene> > > > > > > _______________________________________________ > > Emc-users mailing list > > [email protected] > > https://lists.sourceforge.net/lists/listinfo/emc-users > > A quick test would be to ping a fast host (with say a 200 byte packet) > and look at the ping times. > > Note that there is at least one person using a RPI3 connected to a > Mesa Ethernet card using the RPIs built in Ethernet with success even > with the USB bridge. They did have to lower the servo thread rate to > 500 Hz... > I'm running a kilohertz on mine, but I have a jog-thread at 1 or 2 hundred hz, that handles all the manual stuff. Jog dials so I can drive it by hand and some other "gingerbread" in the hal file. The only place where I need more speed is in the video, its best described as glacial. > > > > Peter Wallace > Mesa Electronics > > (\__/) > (='.'=) This is Bunny. Copy and paste bunny into your > (")_(") signature to help him gain world domination. > > > > _______________________________________________ > 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) If we desire respect for the law, we must first make the law respectable. - Louis D. Brandeis Genes Web page <http://geneslinuxbox.net:6309/gene> _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
