Connecting to RPi Pico using Serial over TCP connection

[kc64]

I have mounted a Pico to the USB port of a remote computer and then ran the tcp_serial_redirect tool that is part of the pySerial package. Using PuTTY, I can connect to it without issue using a raw socket, the remote machine address, and the port number I specified. Is there a connection method in belay to support this type of connection?

[BrianPugh]

Hey @kc64 !

I wasn't familiar with tcp_serial_redirect.py, but I was able to get it working without too much trouble (use the newly released version of Belay, v0.22.5).

Steps (running blink demo on a pi pico):

1. Modify the blink example so that the device is created with a blank username. A blank username will cause telnet to connect without authentication:

   device = belay.Device(args.port, user="")
   

2. In the pyserial/examples directory, run:

   $ python tcp_serial_redirect.py /dev/ttyUSB0 115200  # replace device port with your device port
   --- TCP/IP to Serial redirect on /dev/cu.usbmodem12401  115200,8,N,1 ---
   --- type Ctrl-C / BREAK to quit
   Waiting for connection on 7777...

3. In a different terminal, at the root belay directory, run the modified example:

   $ $ python examples/01_blink_led/main.py --port=127.0.0.1:7777
   Printing from device; turning LED to True.
   Printing from device; turning LED to False.
   Printing from device; turning LED to True.

And it should work! Note that the builtin telnetlib library was removed in the newly released python 3.13, so this telnet feature will not work on python 3.13. It seems like the solution is to just vendor the file into Belay. I'll do this if there's a need!

[kc64]

Hi @BrianPugh --

Again with the super fast, very helpful support. Many thanks for that. I've been using the new version with some success and have only had one problem that I can't explain presently--the Pico dropped into FS mode. I'll keep my eye on this one in case it recurs. Another observation is that if I connect to the Pico using Putty, there is no delay before I can start using the device. The REPL is immediately available. On the other hand, if I connect via a python script, there appears to be a 3-5 second delay before my belay.Device.__call__ instances start working.

[BrianPugh]

Give v0.22.6 a try, it should be much much faster. I also vendored telnetlib in this release, so it's now python3.13 compatible.

[kc64]

It's working wonderfully. Many thanks!