Stan2004;
I don't have the subscription level that allows me to simply send you a direct post, so I have to resort to 'replying' to a previous post even though it might not be directly related to what I wish to talk about at this time -- it's actually somewhat related.
I have everything I need in the way of IR detection so I'm able to detect when one of my 3 engines is at some particular point on the layout, so I can then take some action.
Here is my 'real' problem: Can you think of some way (with 'reasonable' cost) that I can detect the particular engine that has come into 'view' of the area of the layout that is of current interest?
To say it another way: How could I tell that my GG1 is the engine I'm detecting as opposed to one of the other engines like the GP9 or the 2-8-0 steamer?
Some of the ways that exist are to process an image of the engine taken in real-time, RFID, etc.
I was hoping to not have to install any active circuit on the train (only passive circuits) and thereby provide all active circuitry somewhere on the layout nearby the point of detection if necessary.
The idea of using a camera to take a picture (JPEG file) and then process it to identify the engine seems like it might be considerable work (probably have to use OpenCV library) and I don't know if the horsepower I'd need would be there in an Arduino or Raspberry Pi micro controller.
On the other hand, RFID appears to be promising except I have to use a very small RFID tag with a very small antenna and that means the RFID reader must be very close to the tag in order to sense the tags response.
Currently, I'm considering the PN532 NFC/RFID Controller Shield for Arduino from Adafruit.
It can be used with a plastic 'nail' tag which is about 7 mm dia. and 4 mm thick.
If I could place the 'nail' tag (head only) somewhere on each engine without it looking to weird,
then I could put the reader along the tracks so it would be with 2-3 inches of the tag as the train went by. This approach might work?
I can't think of any other way to sense which particular engine has passed the detector.
If you have any ideas, I'd like to hear them.
Ray
