The HC595 example was just to show how the 44.1kHz carrier can be removed from PLAY LOAD SOUND which would be generating the DCC data.
As there is a H-bridge driver between it and the track it is isolated from glitches coming back.
The DCC data is also the power source for the motors and lights etc.

Edit.

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It becomes more complicated when you also want to receive

From what I have read reading from the locomotives is usually only done as part of programming them. Programming is normally done on short piece of track connected to a programmer, so could be a separate project.
The recent Silicon Chip DCC Base Station is an all-in-one unit.

The DCC Base Station software package .zip file is 6.2MB so it would appear DCC can be quite complex.
Edited 2026-03-20 21:58 by phil99

Thanks for the PIO code and other suggestions.

Given my limited skill set in this category, having a second PicoMite doing the actual transmissions using DEVICE BITSTREAM sounds like the easier path.