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-Raspberr >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
