I love operating signals. For me realism is when a train sitting in the hole final gets a green aspect from the dispatcher or just watching a signal get knocked down as a train goes by. I've also had a life long love of electronics. I build my first signal and detection system based on Atmega microcontrollers and bare metal c code. I also made it about as fail-safe as I could (I have a patent for a fail-safe locomotive brake interface from when I worked at Wabtec and have designed flight control hardware and software).
I acquired a bunch of Teensy 3.1/3.2 ARM microcontrollers and decided to use them to control signals in place of the Atmega system I had developed. My system turned out to be hard to update. If you've ever installed a signal system then you know there are always updates. C/MRI is a message protocol on top of RS485 physical layer. I bought some RS485 breakout boards from SparkFun and hacked on a double RJ45 connector. This allowed me to use standard ethernet cables to daisy chain around the layout. I bought an RS485 - USB interface for an MacBook Air I use to run JMRI. I built my nodes using perf board and jumper wires. It takes a long time and I've had issues with reliability and general flakiness. I've built 7 of these and need 4 more for the rest of my layout.
So with the concept fairly proven, I decided to layout a PCB. Of course over the years that I have been developing this, the Teensy 3.2 has gone obsolete. I've considered moving to a Raspberry Nano but I would have to port the software. Each node can handle a control point. There are 3 detector that each have 3 inputs, 3 3-color signals, and 10 control panel inputs. There is also an i2c mast interface that can drive 4 expanders with 16 LEDs each. These are how I interface to my signal bridges.
There is a whole lot more here and I would be happy to answer questions. I plan do a better job of documenting what I have done. I do have the software in GitHub if anyone is interested.
John
I acquired a bunch of Teensy 3.1/3.2 ARM microcontrollers and decided to use them to control signals in place of the Atmega system I had developed. My system turned out to be hard to update. If you've ever installed a signal system then you know there are always updates. C/MRI is a message protocol on top of RS485 physical layer. I bought some RS485 breakout boards from SparkFun and hacked on a double RJ45 connector. This allowed me to use standard ethernet cables to daisy chain around the layout. I bought an RS485 - USB interface for an MacBook Air I use to run JMRI. I built my nodes using perf board and jumper wires. It takes a long time and I've had issues with reliability and general flakiness. I've built 7 of these and need 4 more for the rest of my layout.
So with the concept fairly proven, I decided to layout a PCB. Of course over the years that I have been developing this, the Teensy 3.2 has gone obsolete. I've considered moving to a Raspberry Nano but I would have to port the software. Each node can handle a control point. There are 3 detector that each have 3 inputs, 3 3-color signals, and 10 control panel inputs. There is also an i2c mast interface that can drive 4 expanders with 16 LEDs each. These are how I interface to my signal bridges.
There is a whole lot more here and I would be happy to answer questions. I plan do a better job of documenting what I have done. I do have the software in GitHub if anyone is interested.
John
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