makefiles/tools: enhance miniterm path finding in serial.inc.mk

[crasbe]

Contribution description

Apparently miniterm likes to change the executable name. In very old versions it was miniterm.py, then it was miniterm and now (version 3.5 and higher) it is pyserial-miniterm.

This change enhances the path discovery to select the right one.

Testing procedure

Make sure you have (a recent version of) pyserial installed:

cbuec@W11nMate:~/RIOTstuff/riot-vanilla/RIOT$ pip show pyserial
Name: pyserial
Version: 3.5
Summary: Python Serial Port Extension
Home-page: https://github.com/pyserial/pyserial
Author: Chris Liechti
Author-email: cliechti@gmx.net
License: BSD
Location: /usr/lib/python3/dist-packages
Requires: 
Required-by: adafruit-nrfutil

Run your favorite application with RIOT_TERMINAL=miniterm.

Behavior on master:

cbuec@W11nMate:~/RIOTstuff/riot-vanilla/RIOT$ RIOT_TERMINAL=miniterm BOARD=nrf52840dk make -C tests/sys/shell flash term -j
make: Entering directory '/home/cbuec/RIOTstuff/riot-vanilla/RIOT/tests/sys/shell'
Building application "tests_shell" for "nrf52840dk" with CPU "nrf52".

"make" -C /home/cbuec/RIOTstuff/riot-vanilla/RIOT/pkg/cmsis/ 
...
J-Link>exit

Script processing completed.

Terminal program miniterm is required but not found in PATH.  Aborting.
make: *** [/home/cbuec/RIOTstuff/riot-vanilla/RIOT/tests/sys/shell/../../../Makefile.include:869: term] Error 1
make: Leaving directory '/home/cbuec/RIOTstuff/riot-vanilla/RIOT/tests/sys/shell'

Behavior with this PR:

cbuec@W11nMate:~/RIOTstuff/riot-vanilla/RIOT$ RIOT_TERMINAL=miniterm BOARD=nrf52840dk make -C tests/sys/shell flash term -j
make: Entering directory '/home/cbuec/RIOTstuff/riot-vanilla/RIOT/tests/sys/shell'
Building application "tests_shell" for "nrf52840dk" with CPU "nrf52".

"make" -C /home/cbuec/RIOTstuff/riot-vanilla/RIOT/pkg/cmsis/ 
...
J-Link>exit

Script processing completed.

pyserial-miniterm --eol LF "/dev/ttyACM0" "115200"  
--- Miniterm on /dev/ttyACM0  115200,8,N,1 ---
--- Quit: Ctrl+] | Menu: Ctrl+T | Help: Ctrl+T followed by Ctrl+H ---
main(): This is RIOT! (Version: 2026.04-devel-410-gecc128-pr/miniterm)
test_shell.
>

Issues/PRs references

Found while testing #22207.

Declaration of AI-Tools / LLMs usage:

AI-Tools / LLMs that were used are:

• none

[crasbe]

I also added some information about the correct miniterm in the Guides now :)

[crasbe]

Also unified the references to miniterm in other documents, some were outdated (like using miniterm.py).

[AnnsAnns]

Feel free to squash after this change 👍

[riot-ci]

Murdock results

✔️ PASSED

7f14beb treewide: update documentation regarding miniterm

Success	Failures	Total	Runtime
1	0	1	02m:52s

Artifacts

• Documentation preview

[AnnsAnns]

ty for looking into this 😄