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 <http://combustory.com/wiki/index.php/Arduino_Communications_Device_Naming_with_udev>


        


        


    Arduino Communications Device Naming with udev - Combustory

<http://combustory.com/wiki/index.php/Arduino_Communications_Device_Naming_with_udev>


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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