[SOLVED] Recover from Arduino disconnect

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I’ve got Pimatic (current version 0.9.43) doing its thing for a couple of years now to great satisfactory. Thank you guys for that, i really hope the project stays alive.

Today when i got home my RF stuff wasn’t working anymore. Analyzing the logs, it seems to me that the connection with the Arduino got interrupted for just a short time:

kern.log says:

Dec 28 15:18:34 raspberrypi kernel: [1775550.638095] usb 1-1.2-port2: disabled by hub (EMI?), re-enabling...

Dec 28 15:18:34 raspberrypi kernel: [1775550.638550] usb 1-1.2.2: USB disconnect, device number 5

Dec 28 15:18:34 raspberrypi kernel: [1775550.936066] usb 1-1.2.2: new full-speed USB device number 7 using dwc_otg

Dec 28 15:18:35 raspberrypi kernel: [1775551.080515] usb 1-1.2.2: New USB device found, idVendor=2341, idProduct=0043

Dec 28 15:18:35 raspberrypi kernel: [1775551.080534] usb 1-1.2.2: New USB device strings: Mfr=1, Product=2, SerialNumber=220

Dec 28 15:18:35 raspberrypi kernel: [1775551.080542] usb 1-1.2.2: Manufacturer: Arduino (www.arduino.cc)

Dec 28 15:18:35 raspberrypi kernel: [1775551.080550] usb 1-1.2.2: SerialNumber: 5563930393435161E0F1

Dec 28 15:18:35 raspberrypi kernel: [1775551.081799] cdc_acm 1-1.2.2:1.0: ttyACM1: USB ACM device

So the Arduino reconnects, but Pimatic isn’t aware of that because it’s now ttyACM1 instead of ttyACM0.

Of course pimatic-daemon.log says a few minutes later:

15:23:22.567 [pimatic-homeduino] warn: Couldn't connect (Serialport not open.), retrying...

Just restarting Pimatic doesn’t help:

17:55:46.989 [pimatic-homeduino] error: Couldn't connect to homeduino device: Cannot open /dev/ttyACM0.

After I rebooted the entire Pi things worked again.

Questions:

What could have caused the short disconnection to the Arduino? It’s connected via a powered hub with no other usb devices on it.

How do i deal with this without rebooting the whole system?

@fregger “It’s connected via a powered hub with no other usb devices on it.”

Uhh, why?
How long is the usb cable?
Is it a thin cable?
Is it close to electronic’s or lying on a power cable?

There is no way around a reboot because you cant open the serialport again(that is why it switches to a new number)

I dont know if this could be a fix but you can try it.

Instead of specifying the right usb port, you can also use the serial of the device.

Find it by doing this command;

ls -l /dev/serial/by-id

This will output something like:

13 Dec 24 14:19 usb-1a86_USB2.0-Serial-if00-port0 -> ../../ttyUSB0

Now, in homeduino, remove /dev/ttyUSB0 under serialDevice section.

Replace it with(use the output from earlier, dont copy this exactly):

/dev/serial/by-id/usb-1a86_USB2.0-Serial-if00-port0

@gleno0h Thanx, i’ll give that a try!

@fregger “It’s connected via a powered hub with no other usb devices on it.”

Uhh, why?
How long is the usb cable?
Is it a thin cable?
Is it close to electronic’s or lying on a power cable?

@gleno0h It’s a 1 meter cable with a 3mm diameter, close to electronics but not lying on a power cable.

@gleno0h I guess you’re going to suggest to replace it with a 50 cm 5mm diameter cable. I implemented your serialDevice tip, so as soon as I find another cable we’ll see if I can replace it without screwing up Pimatic

@fregger haha indeed. Lets wait and see

I also had this issue in the beginning… It was because of my arduino nano lying on a power cable…

@gleno0h I found another cable. After reconnecting Pimatic still looks at the wrong serialport but I can solve that by just restarting Pimatic without having to reboot the whole system. Or is there a way to just reload the homeduino plugin?

Just reloading doesn´t work, tried this many times.
Once i found a script that restarts USB, didn´t work.
You have to reboot…

@michael-rudek Thanks to the serialDevice solution i don’t have to reboot anymore, it’s enough to just restart Pimatic so that’s progress I guess I could make a rule for that based on the log entries.

Gleno0h´s solution did not work for me.
I´m getting a

[pimatic-homeduino] error: Error: Cannot open /dev/serial/by-idusb-1a86_USB2.0-Serial-if00-port0
[pimatic-homeduino] error:>    at Error (native)
Unhandled rejection Error: Cannot open /dev/serial/by-idusb-1a86_USB2.0-Serial-if00-port0
    at Error (native)

@michael-rudek There’s a forward slash missing between ‘by-id’ and ‘usb-1a86_USB2.0-Serial-if00-port0’

Thanks.
Seems that i made this mistake twice

@gleno0h said in Recover from Arduino disconnect:

@fregger “It’s connected via a powered hub with no other usb devices on it.”
Uhh, why?

That’s a power thing. I boot from an external USB disk and I have had issues with low power from the Pi before, so I take no prisoners in regard to this and give each usb device its own power source

@michael-rudek said in Recover from Arduino disconnect:

Once i found a script that restarts USB, didn´t work.

Now that you got things working, did you happen to make the same mistake then? You still have that script?

I think is was from this side:
https://www.computerhilfen.de/info/usb-reset-am-raspberry-pi-usb-ports-zuruecksetzen.html
(German Language)

@michael-rudek That script does exactly what it promises, thanks! But the usb reset still requires a Pimatic restart.

Is there a way to just reload a plugin from the command line? Anybody?

@fregger no. Resetting the usb also doesnt work. You need to find the cause as to why this happens. I have had the same issue, after 2 days or so it stopped working. So ive turned to EspimaticRF by koffienl. Simply put, it allows you to send RF over WiFi.

Now, that became instable and asked for help, which i didnt get. So i have returned to Arduino+RF and have 0 issues now.

Maybe you could try the wifi rf.

As to reopen a serial port through software; forget it. Wont work.

But still, check the debug, check your dmesg log, and find the cause instead of fixing the symptoms

Post your logs if you need help!

After two weeks the disconnect happened again:

/var/log/kern.log:

Jan 11 15:57:31 raspberrypi kernel: [1201673.130772] usb 1-1.2.2: USB disconnect, device number 7

Jan 11 15:57:32 raspberrypi kernel: [1201673.447208] usb 1-1.2.2: new full-speed USB device number 8 using dwc_otg

Pimatic log-reader comes to the rescue.

Added the plugin to to plugins-Array in the config.json file:

{
  "plugin": "log-reader"
}

Then added a sensor for log-entries to the devices section:

{
  "id": "arduino-status",
  "name": "Arduino",
  "class": "LogWatcher",
  "file": "/var/log/kern.log",
  "attributes": [
    "arduino-state"
  ],
  "lines": [
    {
      "match": "USB disconnect",
      "predicate": "usb disconnected",
      "arduino-state": "disconnected"
    },
    {
      "match": "new full-speed USB device",
      "predicate": "usb connected",
      "arduino-state": "connected"
    }
  ]
}

Then I made some rules:

when usb disconnected then send chat tojid:"me@someaddress" message:"Arduino disconnect"
when usb connected then restart pimatic

This gives me a fully automated recovery after the disconnect, without rebooting the Pi.

@fregger hm that is still not realy a fix. You could try and symlink the usb device.

If you make a symlink called “/dev/arduino”, no matter which port it uses, it will always be “/dev/arduino” as long as it reconnects after a crash, it should work.

See this post