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Setting up Coral dev board

· 3 min read
Frank Chen
Frank Chen
Backend & Applied ML Engineer

Set up Coral Dev Board for employing an Edge TPU coprocessor.

Prototype new projects demanding fast on-device inference for the ML models.

Background​

The official documents Get started with the Dev Board contains comprehensive how-to contents and rich examples. Here are just some experiences from myself. You can always go back to the official website to review and get the details.

The recommended method to access the Coral board is using Mendel Development Tool (mdt), which is required to be installed on your host machine alongside the Python. Common steps to enter the shell terminal from mdt are in following:

  1. mdt tool generate a pair of SSH keys, save the private key on the host and push the public key to the Coral using http via 41337 port.
  2. Coral board has a running a mdt-keymaster server that is listening 41337 port, and put the public key into ~/.ssh/authorized_keys.
  3. mdt shell now can login to the shell terminal of Coral board like ssh mendel@192.168.100.2 when connecting over USB-C(OTG) or ssh mendel@indigo-quill.local over the same network where your host PC is.
info

Coral board is set up by disabling password login in OpenSSH in default, so it must be provided with SSH key otherwise you change the setting to be like PasswordAuthentication yes.

note

You can check the key master by,

mendel@indigo-quill:~$ lsof -i:41337
COMMAND    PID   USER   FD   TYPE DEVICE SIZE/OFF NODE NAME
mdt-keyma 7846 mendel    5u  IPv4  20302      0t0  TCP 192.168.100.2:41337 (LISTEN)
mdt-keyma 7847 mendel    6u  IPv4  20619      0t0  TCP 192.168.101.2:41337 (LISTEN)

Although mdt maybe facilitate the access to the Coral board, some magics and additional steps are kept from sight.

To do not use mdt, we need access the dev board through serial console instead of mdt keymaster server, to make configuration.

There are general ways to access a just-setup Coral in brief steps:

  1. Connect to Coral board's serial console by the instructions Connect to the Dev Board's serial console
  2. Log into the Dev board by username: mendel and password: mendel in default.
  3. Enable SSH Password Authentication. Edit /etc/ssh/sshd_config to change PasswordAuthentication no to PasswordAuthentication yes, and sudo service ssh restart to restart the ssh service.
  4. Log into the shell using username: mendel and password: mendel.
  5. If you want to keep the secure shell, generate private SSH key stored in host and public SSH key saved into Coral.

References​