Hi Kinsa,
Thanks again for your advise.
For the spindle pwm signal, I should have more faith and read more carefully the message trail, sorry about that. I did also a bit of code reading (firmware and driver) and I understand now just enough how it works to fit the *.hal file to my environment.
I decided modify the hardware (ground the enable inputs of the 74HCT367 permanently) in order to keep the enable output PB2 (pin6 of the PIC32) as an active signal. This is especially useful since my stepper board needs a common “amplifier enable” signal which is deactivated e.g. after an e-stop.
So, I solved my problems partly by modifying the *.hal file and partly by modifying the firmware. For the latter, I believe it is the only way to invert a some of the signals, such as Z-dir and spindle-pwm, since they are generated by the PIC32 itself, beyond the reach of the *.hal file.
Herewith the modified *.hal and *.ini files, as they can be useful to some else. Also a second attempt for the picture.

- picnc.JPG (58.2 KiB) Viewed 9157 times
Many thanks again and all the best,
Jean-Renier.