Gadget providing serial-port slot

snap
4

Well, rolling your own gadget with additional serial interfaces is rather trivial:

  • install snapcraft:
snap install snapcraft --classic
  • clone the gadget source tree
git clone https://github.com/snapcore/pc-amd64-gadget.git
cd pc-amd64-gadget
  • now edit snapcraft.yaml and append something like (this would be for four RS232 ports, i’m not sure how RS485 shows up in /dev, you would have to adjust accordingly):
slots:
    serial0:
      interface: serial-port
      path: /dev/ttyS0
    serial1:
      interface: serial-port
      path: /dev/ttyS1
    serial2:
      interface: serial-port
      path: /dev/ttyS2
    serial3:
      interface: serial-port
      path: /dev/ttyS3
  • and now you just call snapcraft in the source dir and a gadget snap gets produced.

To build an image with this gadget snap you do the following:

  • install ubuntu-image:
snap install ubuntu-image --beta --classic
  • get the model assertion (image description and signature):
snap known --remote model series=16 model=pc-amd64 brand-id=canonical >pc.model
  • now tell ubuntu-image to build a new image that includes the new gadget snap:
sudo ubuntu-image --channel stable --extra-snaps /path/to/your/gadget.snap /path/to/pc.model

this produces a new “pc.img” file, that you can write to the HDD of your device.

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