>I'm struggling to understand what you mean exactly by serial number in this
>context.
Yes, FTDI has a unique serial number. Although I have heard of duplicates, but
that would not be the norm. I cannot speak for other USB chip sets.
Well I say I will move on from Ubuntu, but I still have it, albeit old. Yet
even this old Ubuntu version I have is more current than RedHat (Centos) 7 on
libraries. So I still use it. Time will tell if Debian can fully replace
Ubuntu. They do a good job of coordinating alot of software. However my hope is
Debian does too. Time will tell and I am not in a hurry. Mainly I use Debian
for embedded stuff and I have come to really like it.
On Thursday, February 28, 2019, 11:27:42 AM EST, Pete Soper via TriEmbed
<[email protected]> wrote:
On 2/28/19 8:54 AM, John Vaughters via TriEmbed wrote:
> But I need to go a step further. To assign a name like "NW-FOO" to the
> XDS110 in the NW corner of my "test range" I'd need to interpose in Udev
> somehow so it could do the thing to determine which is which.
Right, so are you saying that you do not have unique serial #'s?. The
technique described relies on specific devices with serial numbers, I'm
struggling to understand what you mean exactly by serial number in this
context. Does each USB interface chip (or emulation hardware) have a unique
serial number along with the manufacturer ID and device ID that we see with
lsusb? I just assumed they don't and it's up to me to extract a standard ID
(such as can be programmed into the debug probes) or something ad hoc (e.g.
with a custom Arduino boot loader recognizing a "gimme your UID" command).
I went backwards from you, spending about 10 years with Debian Stable before
going to the dark side with Ubuntu 13. I regret that, but am afraid some key
tool my work depends on simply won't play with what was a solid rock of
reliability. Maybe I should grease up VirtualBox and see if I could reverse
course.
-Pete
so if you have to change an Arduino Nano out for instance, you would also
need to change the rule to use the new serial number. UDEV is extremely
flexible and I haven't even touched the surface of it, so if you write more
generic rules to just capture Arduino vs XYX, then I am sure you could find a
rule to increment your naming. I used this technique to utilize the serial
number to always connect to a specific name. It worked quite well for fixing
reconnects where it would normally increment. However, it still did not fix
just plain disconnects common in USB. I am not a fan of the USB software layer
and I absolutely despise its physical connections. Having said all that I still
use it in many ways, I have to, it's all there is for many things. And this
solution described with UDEV and serial #'s actually worked quite well at
solving the vast majority of issues and was quite stable. Probably fine for
non-critical uses.
Example FTDI Serial #
ATTRS{serial}=="A600G5OZ"
>I regret going with Ubuntu 18.04
You are making me feel better about keeping my Ubuntu 16 or is it 14? Anyway,
I am done with Ubuntu. it drives me crazy in the same way that windows does, by
making decisions for you and assuming the user needs to be probed constantly to
act. I have always been a RedHat person, but thanks to Rpi and many other
embedded devices, I am now a HUGE fan of Debian. I will not be going to Ubuntu
for new installs unless I am setting it up for non-technical users, then Ubuntu
is still the #1 go to. For me though, Ubuntu just annoys the crap out of me in
so many ways. The problem with RedHat (Centos) is it just doesn't keep up to
date for newer software, so I have to use something else for that. It has been
Ubuntu, but now it's Debian.
On Wednesday, February 27, 2019, 8:55:07 PM EST, Pete Soper via TriEmbed
<[email protected]> wrote:
On 2/27/19 7:16 PM, John Vaughters via TriEmbed wrote:
Pete,
If you are using the same USB devices all the time and do not expect changes,
consider doing udev rules. Below is an article I wrote about it. Basically it
recognizes your USB device based on certain ID's and you can name the device
whatever you want. As far as communicating, "expect" scripts is as good as any
tool I can think of. The only thing that is probably Thanks. That's a nice
how-to and will make it easy to differentiate between the TI XDS110 debug
probes and Beaglebone boards that both manifest as /dev/ttyACMn and between
instances of custom devices and the Arduino Nano's I'm using to run some motors
that both manifest as /dev/ttyUSBn. But I need to go a step further. To assign
a name like "NW-FOO" to the XDS110 in the NW corner of my "test range" I'd need
to interpose in Udev somehow so it could do the thing to determine which is
which. For the XDS110 there's a TI program that (if you repeat it enough times:
flaky as heck) puts out strings including the ID string, but for the custom
device I need to use expect to poke something into the port and get back the ID
(and same for the Arduino motor controllers).
So the question is whether there's a hook mechanism with Udev that would allow
running a command as a side effect of the device's detection and name
assignment under /dev. Especially if that could be run as root I could create
the symbolic link and properly set its group id. Or maybe the invoked
program/script could simply rename the device after it's probed it?
I agree that USB has got further to go. I regret going with Ubuntu 18.04 for
my latest PC 'cause Code Composer Studio seems to be much less able to manage
the debug probes than when it's running on 16.04. Over on the TriLUG list
there's been griping about 18.04 having regressions and that matches my
experience.
-Pete
better is Tera-Term, but that is strictly windows. It is quite good though
and I wrote a tool to run scripts to 300 edge routers using Tera-Term. One
thing I used to do is use "socat" to send the serial device to a raw TCP port
and communicate over the network. In general I do everything I can to not
communicate to USB devices due to their constant connection issues. I prefer
using UART if possible.
Good Luck,
John Vaughters
Arduino Communications Device Naming with udev - Combustory
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Arduino Communications Device Naming with udev - Combustory
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On Wednesday, February 27, 2019, 4:41:50 PM EST, Pete Soper via TriEmbed
<[email protected]> wrote:
It's been many years since I used the Unix "expect" command but that was
the industrial strength solution for automated interaction with a serial
connection such as via ssh where you specify a "script" of "this is
sent, this is what's received back", interactions and the logic to take
actions based on the interaction details. What's out there now that I
should be using, or is this still the best way to go? My host
environment choices are Linux or Cygwin (inside a VM).
My situation is that I have three or four flavors of device that I need
to connect to with either ssh or a terminal emulator where a script of
some sort dictates what I have to send and what I expect back. This, in
turn, is to deal with the musical chair situation with USB connections
such as when I get intermittent electrical service from Duke Energy (at
no extra cost!) I've got an automated test system where there are, for
example, /dev/ttyACM{0,1,2,3,4,5,6,7}, /dev/USB{0,1,2,3}, etc, and I
need to establish and keep fresh meaninfully named symlinks that get
associated with the right devices assigned randomly by system startups,
being forced to unconnect/reconnect cables, etc.
.
Thanks,
Pete
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