Interfacing Hardware Circuit and Assembly

[TerryJC]

Attached is an early draft of the Interfacing Hardware circuit diagram and basic layout and wiring diagrams. There is work to be done on the Veroboard design and layout and there will be more Terminal connections than the 14 shown (this has been recycled from the River System Interlacing Assembly drawing).

My intention is to assemble this Interfacing Hardware over the coming week or so and update this diagram at the same time. Once it has been built, then it can be wired to the railway equipment by someone else by following the labels on TB1. There should be no requirement for other railway volunteers to touch the internal components of the assembly, especially once it has been integrated.

Any comments or questions welcome!

By the way. The drawing has been produced using LibreOffice because it is available for free across all major platforms (Windows, Mac, Linux, etc). Fairly new versions of MS Office may be able to open it, but it may be better to download and install LibreOffice, or at least an Open Document Format Viewer.

[TerryJC]

Here is the latest draft version of the Interfacing Hardware circuit diagram, etc. This version is almost complete but the diagram will need to be tested during assembly and off-line testing of the motor drive, etc.

I have commenced the build, (see Sheet 5 of the drawing), but cannot complete the design or build until I know what the specification of the Traffic Signal LEDs is (see viewtopic.php?f=19&t=120#p1770. If obtaining the specification of the LEDs is a problem, then please leave one of each for me to test somewhere that I can find them. Alternatively let me know the part numbers and I'll look it up.

I have a bit more work to do this week on the Bells and River Systems, but I'd like to complete assembly and testing as soon as possible so that the system can be installed and integrated on site.

[TerryJC]

Sitrep:

I believe that I have now fixed the Bells system and have been soak testing it for much of this weekend. This has allowed me to get on with the Underground hardware assembly.

The build of the parts for this assembly is now largely complete; all wires have been cut to length and terminated and the Veroboard has been assembled. All that remains before I can fit the parts to the baseboard and wire up the system is to solder header pins to the Pi and the DC/DC Converter; a relatively short job.

I have completed the first draft of the software, but it needs debugging. I realised that to do this with any real hope of detecting any bugs before the unit is installed into the Railway Room I needed a test jig. I have spent some of this weekend designing and testing this. You can see the latest design for the Underground Railway Hardware Assy, including the Test Jig, in the attached updated Circuit.

I won't be doing any more today and I will probably not be able to do anything tomorrow, unless the boys from Canford School don't come in the afternoon.

This means that the earliest I'll be able to complete and test the assembly is likely to be Tuesday, so I am aiming to be ready to install it on Wednesday if the Railway Room end is ready.

[TerryJC]

Sitrep2:

I had a few issues today, (with WMT Projects and with home stuff), so progress wasn't quite as good as I'd hoped.

The hardware is now fully built and the software runs on a Pi without errors, but not yet in conjunction with the Test Rig. I therefore haven't been able to view the code running through the full sequence of events.

Tomorrow, I'll complete the testing and report back.

We need to ensure that the system in the Railway Room is ready to receive the hardware and then arrange a date to get together.

[TerryJC]

I had to spend some time with the River System this morning and so wasn't able to start the testing of the Underground system hardware until this afternoon. The good news is that the train drive software and hardware works and the LED Drivers work, (although I need to get the sequence right). However, I've yet to prove the IR Sensor detection hardware and software. I was having problems with this and then I realised that there is an error on the Veroboard which means I'm going to partially disassemble it to correct the problem. I will then have to run through the testing again, but with a bit of luck I should be able to complete this tomorrow afternoon.

Of course this means that I won't be able to integrate the system into the Railway until early next week However, that still gives us 3 weeks to complete the task, so I think we can do it with time to spare.

[TerryJC]

After my visit to WMT this morning and my conversation with Geoff, I borrowed the made up Traffic Signals and tested the LED Currents and voltages. I can confirm that the optimum performance is obtained at 2.2 V at which voltage a current of 19 mA is flowing. I can therefore proceed with the design of the LED drivers with confidence.

[TerryJC]

The bench testing of the hardware has been completed and is ready for integration on Tuesday. The software is in GitLab (more information may be found at viewtopic.php?f=22&t=123).

Attached is the latest version of the Circuit and Build Instructions.