This post contains a few notes on how to get ssh working on a Google Coral device if you have a mac with Catalina on it. The standard instructions, and in particular the part where you have to use MDT are not working and I describe a workaround on how you can activate ssh without MDT.

How to activate ssh on a Google Coral accelerator board if you have MAC OS Catalina

This is a short blog post where I describe how to activate ssh and work on a Google Coral Device board from your laptop remotely if you have MAC OS Catalina. If you have tried to follow the instructions that you can find on the official website where

https://coral.ai/docs/dev-board/get-started/

you may have got to Section 2, where is described how to connect to the board with MDT (https://coral.ai/docs/dev-board/mdt/). MDT is the Mendel Development Tool and should faciliate several operations when using Mendel Linux distro (that you will install on the Coral Devices if you follow the instructions). According to the official website

Mendel Development Tool (mdt) is a command-line tool that lets you communicate with a device running Mendel Linux. The mdt command facilitates a variety of device actions such as opening a shell, installing Debian packages, pushing and pulling files, and more.

Now there is an important point. The official documentation states

MDT can access the shell on any Mendel device that’s visible on your network

Note the visible on your network part. If you follow the instructions you should connect a data usb-c cable (how to recognize one is unknown at this point but that is for another post) to the data port

and then connect the cable to your development machine (in our case your macbook probably). The connection should basically create a network and make the device visible to your laptop.

Problem is that on Catalina connecting the USB-C cable does not do anything. Not on my laptop and according to several posts I found also for many other people. If you have a Linux machine is no problem, not on Catalina. So you cannot activate ssh as the instructions explain. This may change in the future so just in case, as I am writing, I have tested this with Catalina 10.15.1.

To do that you can do the following:

  1. Open a Terminal and then type screen /dev/cu.SLAB_USBtoUART 115200
  2. Connect the serial cable (see previous figure, or following the official instructions). If you have followed the instructions up to this point you should have done this already once.
  3. Once you connect the serial cable and turn on the Coral you should then see a few lines of text and then a login. You can login with the standard username/password: mendel/mendel.
  4. Start sudo nano /etc/ssh/sshd_config (DISCLAIMER: note that allowing ssh with only password, as I am describing here, is not as safe as using keys, if you do it, please be aware of the risks in case you have sensible data or security is an issue for you. If you are unsure ask someone that can help you with that.)
  5. In the file change PermitRootLogin prohibit-password to PermitRootLogin yes
  6. Then change PasswordAuthentication no to PasswordAuthentication yes
  7. Restart the ssh demon with sudo service ssh restart
  8. Don’t forget to activate wifi on the coral device following the instructions on section 3. in the official documentation https://coral.ai/docs/dev-board/get-started/. Select the network on which your development machine (possibly your mac laptop) is so that the Coral is visible on the network.

You should be all set. The Coral will be reachable by ssh. Note that you will need to know the name of the board that you got during the installation phase.

In case you have questions feel free to drop me an email.