On Thu, 3 Oct 2019, Gene Heskett wrote:
Date: Thu, 3 Oct 2019 10:38:51 -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 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>
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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.
Do you have hardware OpenGL enabled? That makes a huge difference
Peter Wallace
Mesa Electronics
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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
Peter Wallace
Mesa Electronics
(\__/)
(='.'=) This is Bunny. Copy and paste bunny into your
(")_(") signature to help him gain world domination.
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