..and espflash

Note: probe-rs has since making this repo added a "basic remote server" (GitHub PR) as a built-in feature. That may or may not be a better way to go - you should check.

---

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

• 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!).

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 [email protected]		# 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
[email protected]'s password: 

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

Test:

$ ssh [email protected] whoami
probe-rs

Great!!!

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

$ echo "export [email protected]" >> ~/.bashrc 
$ source ~/.bashrc

$ echo $PROBE_RS_REMOTE
[email protected]

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.

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

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.

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

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

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! 🎉🎉

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.

Follow the same docs/cross.md instructions.

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!!

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