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Reply to "Multi-function train detector brainstorming. Ideas wanted!"

gunrunnerjohn posted:

An ambitious list JGL, I think I'd stop designing and start building.   Like you say, with the programmability, you can change and/or expand the functionality.  The more important part at this point, at least IMO, is the I/O provisions to allow you to build the functions that might be desired.

I/O is a bit of a problem but not one that can't be solved.  I'm comparing a couple options still, but I think an I2C 16 bit port expander will solve the I/O concerns.  Most of the inputs are going to be used to select the different features and adjust settings, and most the outputs for programing feedback.  

Consolidated Leo posted:

 

At this point, I'm wondering about some of the components. For example, What type of relay outputs will be available? Are they SPDT (COM, NO, NC) or DPDT? Will the relays be on-board or spun off to a relay module (what Stan2004 likes to call LEGO style)? Also, will the direction sensing outputs come out of the relays or will there be a logic level output as well?

Due to cost considerations I'm looking at SPDT relays.  It looks like I can stick them on board for a couple pennies less than the cost of using pre-made modules, so I think thats the way I'm going to go.  The relays I'm looking at are the exact same ones found on those modules, rated for 10 Amps.  The input will be opto isolated form the uP and will accept logic or track level input. We can get away with quite a bit because high-speed switching is not a concern.  For output, the main output will simply be the NC,NO,Com of the relay, however I plan to also have a header pin out providing the logic level out for folks that want that.  It's possible I could add a jumper to allow the relay to be disconnected.  

christhetrainguy09 posted:

Oh boy this looks like a headache and a half! Some of those features seem a bit redundant .... And some of the features can be done with a isolated rail section without the hours of programming it might take to write the code let alone work out any kinks!

 

Which are redundant and in what way?  I'd be happy to remove features that are not needed.  As for the hours of programing and troubleshooting, it doesn't bother me.  I'm not looking for help programing or debugging my code, only help in figuring out what folks would find useful.  Honestly I can't see any of the listed features taking much more than a hand full of If statements to accomplish.  

On block signals, I had not really thought about that much, and I know there are several products out there for that.  I'm figuring this more for accessory activation than signaling, but could look into signaling later on.  

christhetrainguy09 posted:
I figured rather than keep adding to the list, lets knock some of these features off. <
 

Again, which ones, and for what reason?  If there are things that over-lap, then yea, no point in doing the same thing twice, but I don't see any reason not to program in every option that might be wanted as long as it doesn't require more hardware.  It doesn't cost extra to add lines of code.  


For a general update, I'll be tied up with work for much of the next several days.  It shouldn't matter much as I expect parts to take a couple weeks to arrive.  On that, I've ordered some things to test out; multi-turn pots, some Nano clones, stuff like that.  I Still haven't decided which port expander I want to use, or if I will just use shift registers.  I'm leaning toward the port expander though, because it takes up less board space, but need to look into the overhead the wire library would add to the sketch.  

In my free time over the next couple days I'm going to try writing the code for each of the features and try them out.  I don't expect anything to be particularly difficult, but could be wrong.  

I've thought of a couple more complicated functions, such as involving limit switches for specialized accessories, but I don't think it worth the trouble just yet, instead deciding to leave that for later as well.  


One question more from the operating end than the tech end.  Is the 1.5 second or so boot time after power is applied a problem?  Leaving this there makes it simple for a user to install new updated to the device.  On the other hand, the device can be made to boot instantly at the expense of requiring an additional piece of hardware to reprogram with new firmware.  

JGL

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