My project is:-
To come up with a low-cost control system for model railways. Currently DCC is super expensive and with modern electronics I believe this expense can be avoided and even if the wheel is being reinvented this can still be a learning exercise.
This is a large project so would have to be approached step by step with proof of concept breadboarding and then a layout test. Plenty to do but incrementally. Now I am hammering track down onto a cork bed placed on 1.5m by 1.2m baseboard. A DC linear PSU is built but I may build another one with a few unusual changes!!!
Summary of thoughts.
Power and communication.
Rail tracks to carry DC (any polarity) throughout the layout. Preferably using a linear supply to avoid transmitted noise and interference with signalling.
Communications could be.
Differential signalling on top of the DC sent along the track. This would be stripped off the power rail on each train and at each intelligent node (think point controller etc). Using an existing protocol. First thought is modbus to put a veneer of standardisation into the mix. https://www.schneider-electric.co.uk/en/faqs/FA168406/ . I can see degradation of signal quality being a challenge caused by track LCR. Also, how to modulate the power rail? Feed in a signal into an external reference voltage pin on a linear variable regulator? Lots of ideas and areas to play with.
Infra-red. Increasing the processing power in each node and setting up a mesh style network, so packets can be routed between points outside of line of sight. Reflections may be both useful and a nuisance. Physically simple but the software is going to be a substantial challenge. Should be immune to electrical interference and produce none. I must design for remote controls that use infra-red. They could be controllers as well as a source of interference.
WIFI. I believe there is an Australian group working on this. This is a very noisy environment in my house I am not convinced that it is going to be viable but cheap enough to experiment.
Maybe a central controller keeping a firmware-based map of the layout. User control is moderated by what is scale or track appropriate. Some built in rules would be needed.
Or a mesh of nodes that on bootup/reset talk to their neighbours and use a rule set to create a part map of the total layout. How to differentiate between connected and switched (from a rail point of view) out track is going to be an issue. At this point I suspect I may need central mapping and self-discovery to work together.
Each node runs the same code but with appropriate attributes. A point controller does not have an associated velocity but will have an off/on state with itself and as needed its twin on an adjacent track. As a train approaches a road crossing all the appropriate nodes individually go through the correct sequences. A person may decide to swap trains from a siding with one on the main track but having given the command the individual trains handle the movements and switching. So even if nodes are independent there may still need to be a hierarchy.
To begin with a simple loop is sufficient and I am at the breadboarding stage for each of the signalling options let alone controllers.
Looking at power option 1. Modulation of DC power for differential signalling. Signal degradation on a track loop at each point of the track. High frequency/broadband Interference from power pickup on each train.