probe-rs remote

..and espflash

This repo provides scripts to be run on a Mac/Linux developer account that make probe-rs and espflash running on another computer feel like a local tool.

This allows:

• galvanic separation of the attached electronics from the main development computer
• developing open source code so that people can choose, whether they prefer local or remote probe-rs/espflash, without any changes to the build files

Supported commands

• probe-rs
  • help, list, info, erase, reset, run
• espflash
  • help, board-info, erase-*, hold-in-reset, monitor, reset, checksum-md5, flash, partition-table, write-bin

Requirements

• A Raspberry Pi 3B

  • ..with a stable IP address

  Use ifconfig to see the IP address. Below, we use 192.168.1.199 (replace with yours!).

Steps

ssh connection to the remote machine

Following [1]:

Creating a dedicated user (optional)

You might want to create a separate account on the relay machine, just for running probe-rs. This way, the ssh key pair won't allow access to full resources, just running probe-rs.

$ sudo adduser probe-rs

Give some pw and press ENTER for the defaults.

>Note: Consider another user name if you find it confusing to use also `espflash` under the `probe-rs` user. `#legacy`

On the development machine, create a key pair for using ssh without passwords:

$ ssh-keygen -t rsa

Pass the public key to the probe-rs relay:

$ ssh-copy-id probe-rs@192.168.1.199		# use your own user and IP!!!
/usr/bin/ssh-copy-id: INFO: Source of key(s) to be installed: "/home/ubuntu/.ssh/id_rsa.pub"
/usr/bin/ssh-copy-id: INFO: attempting to log in with the new key(s), to filter out any that are already installed
/usr/bin/ssh-copy-id: INFO: 1 key(s) remain to be installed -- if you are prompted now it is to install the new keys
probe-rs@192.168.1.199's password: 

Number of key(s) added: 1
[...]

Test:

$ ssh probe-rs@192.168.1.199 whoami
probe-rs

Great!!!

Set the PROBE_RS_REMOTE env.var.

The script (that we head towards..) uses this to see, where the remote account is expected to be.

$ echo "export PROBE_RS_REMOTE=probe-rs@192.168.1.199" >> ~/.bashrc 
$ source ~/.bashrc

$ echo $PROBE_RS_REMOTE
probe-rs@192.168.1.199

Note! If you use some other shell than Bash, please adjust the commands accordingly.

The PROBE_RS_REMOTE is now available, even if you were to restart.

Install probe-rs on the remote machine

The official commands for installing probe-rs do not support Raspberry Pi 3B^|1|, but it can be cross-compiled for the device.

Follow instructions in docs/cross.md to:

• cross-compile probe-rs executable suitable for the Raspberry Pi
• transfer it to the device
• make some system-wide additions (udev rules)
• the same for espflash, too

>`|1|`: >Not supporting Raspberry Pi 3B is not due to oversight, but the fact that its 1GB of RAM is not sufficient for the Rust build system. You can, of course, run Rust-based binaries on any machine.

Then, let's test it remotely:

$ ssh -q $PROBE_RS_REMOTE -t 'bash -ic "probe-rs --version"'
probe-rs 0.25.0 (git commit: 5805879)

We now have the remote machine all set up for running probe-rs via ssh.

Setting up development side

The script to use on your development machine is at sh/probe-rs-remote.sh.

Consider, whether you want to:

• a) just copy it to your favourite location (e.g. ~/bin/), alongside the PATH, renaming to probe-rs in the process, or..

• b) ..have a symbolic link pointing to a clone of this repo. This makes updates easier.

Create a '~/bin' folder on the PATH

$ install -d ~/bin
$ echo PATH="\$PATH:$HOME/bin" >> ~/.bashrc
$ source ~/.bashrc

a) copy; independent

$ cp sh/probe-rs-remote.sh ~/bin/probe-rs

b) link; points to the repo

$ cd ~/bin
$ ln -s {path-to-repo}/sh/probe-rs-remote.sh probe-rs

[!WARN] An alias would work for your interactive prompt, but not for build files which launch bash in a non-interactive mode.

Test:

$ probe-rs list

Removing previous probe-rs

You can have both a local and the remote probe-rs simultaneously, but most of the time this is not needed, and is just a distraction.

$ ls ~/.cargo/bin/probe-rs

If you have a file there, just remove it:

$ rm ~/.cargo/bin/probe-rs

Using the command

Please attach a device to the remote machine.

$ probe-rs info
[...]

The script only supports a limited number of commands. Have a look at its contents for more info.

Now you have remote probe-rs working, transparently to your build systems. Yay! 🎉🎉

What about espflash?

The process is very similar, but why would you want to have two separate flashing tools, in the first place?

• Many ESP32 projects online use it; it'll be easier to run those.
• espflash can use either of the USB ports (UART or JTAG) of your devkit; probe-rs uses USB/JTAG only
• The approaches are different: since probe-rs goes deeper into the MCU, its use sometimes causes incompatibilities that use of espflash avoids.

Cross-compile

Follow the same docs/cross.md instructions.

Testing

On the development machine:

$ espflash board-info

Naming note!

We currently use the probe-rs remote user name, and PROBE_RS_REMOTE env.var. also for espflash. The reason is only historic - did the ssh bridging to ssh, first.

You may suggest better suiting names!!

References

• [1]: "Streamlining Secure Remote Access: A Guide to Passwordless SSH Connections Between Linux Servers" (blog; Sep'23)