4. Environment

4.1. Targets

OpenCN framework supports emulated and real targets for arm64 and x86 architectures. 4 targets are supported:

  • x86 platform, called x86

  • Raspberry PI 4, called rpi4_64

  • Emulated x86 platform, called x86-qemu

  • Emulated ARM64 platform, called virt64

4.2. Material

This paragraph provides information on the needed material for each real platforms.

4.2.1. x86 target

  • A Intel CPU with at least 4 cores

  • An e1000e supported Ethernet controller used for EtherCAT communications

  • A second Ethernet controller

  • At least one USB free port, after connecting a keyboard and mouse.

  • USB thumb drive (at least 200 MB at the time of writing)

4.2.2. Raspberry PI

  • A Raspberry PI 4 board

  • A SD card

  • (optional) An USB to serial cable to interact with the console of the OpenCN target.

  • ETHERNET DUAL. It is used to communicate with the Host PC.

4.2.3. Raspberry Compute Module 4

  • A Raspberry Compute Module 4 module

  • A Raspberry Compute Module 4 main board with 2 ethernet interfaces (one should be the CM4 original ETH).

  • A SD card

  • (optional) An USB to serial cable to interact with the console of the OpenCN target.

The following base board have been tested:

Note

The CM4 NVME NAS BOX provides 2 locations for SSD nvme drives. Here are information on how to deal with this drives

4.3. Configuration

4.3.1. Target IP addresses

On all platforms, the Ethernet interface are configured with a static IP address. The address is:

  • eth0 : 192.168.53.15

  • eth1 : 192.168.53.16 (Raspberry only)

A DHCP server is also running on the platform. It provides an IP address to the Host PC.

4.3.2. ssh

A ssh server is present on each supported platforms. It then is possible to connect to a OpenCN target with it. The password is root

Example:

$ ssh root@192.168.53.15

Warning

The results of the halcmd show is only displayed on the main console. It is not showed on ssh terminals.

It is also possible to use scp (OpenSSH secure file copy) to copy files from/to an OpenCN platform. The scp command format is following:

$ scp <SRC_FILE> <TARGET_FOLDER>

The format, of a remote destination, is the following: root@<IP_ADDRESS>:<PATH_ON_TARGET>

The next command shows how to use scp to copy micro3.hal file from an OpenCN target to a local directory of the HOST PC, the default password is root.

$ scp root@192.168.53.15:/root/micro3.hal .
A avahi (zero conf server) is also available. It simplifies connection to an OpenCN target: instead of using an IP address, it is possible to use the target hostname + .local (opencn.local in our case).

It means that is this possible to connect to an OpenCN target by using opencn.local instead of 192.168.53.15. Examples:

$ ping opencn.local
$ ssh root@opencn.local

Warning

avahi only works if the OpenCN target and the HOST PC are connected on the same LAN.

4.3.2.1. Avoid host identification

Everytime you will rebuild the target, you will get an error because the remote host has changed it’s identification.
To avoid identification checking, you can create a config file on your host/GUI PC under ~/.ssh/config that contain :
Host 192.168.53.15
        StrictHostKeyChecking no
        UserKnownHostsFile=/dev/null

4.3.3. sshfs

It is possible to mount a folder of the target platform on the HOST PC using sshfs.

It is, for example, possible to mount the root folder on the HOST PC to be able to edit an HAL file.

The sshfs command use the same format as scp. The next commands shows how to mount the root folder to the fs folder present on the current directory of the HOST PC.

The command umount can be used to stop (umount) the folder sharing,

$ sshfs root@192.168.53.15:/root fs
$ umount fs

4.4. SSD drive

When a lots of data have to be logged, it can be better to store them on a SSD drive instead of the SD Card. SSD drive are much faster (and bigger).

A SSD drive can be connected on a USB port, with an adaptation or using a CM4 box like the CM4 NVME NAS BOX.

4.4.1. Usage

Here are the commands to use to make the drive mounted and ready to use.

  • Check the disk name

$ lsblk

the drive name is similar to nvme0nX where X is the disk number.

  • Partition creation

$ (echo n; echo p; echo 1; echo ; echo ; echo w) | fdisk /dev/nvme0nX

or

$ sudo parted /dev/nvme0nX --script mklabel msdos mkpart primary ext4 0% 100%

  • Format the partition as ext4.

$ mkfs.ext4 /dev/nvme0nXp1

$ Mount the partition on the OpenCN target.

$ mkdir <MOUNT POINT>
$ mount /dev/nvme0nXp1 <MOUNT POINT>

The possible <MOUNT POINT>, often used in Linux environment: /mnt/data