Adapting a 5 amp Arduino motor board for a DCC Ex command station, and why my Raspberry Pi had to go

I'd been suspecting for a while that the Raspberry Pi 4 wasn't performing well enough for JMRI and automation, so I decided it was time to prove it.
#modeltrains #modelrailways

[@ianjeffery4773]

Another excellent analysis and diagnosis.

[@WirenwoodModelRailway]

Thank you Ian, that's very kind!

[@BriansModelTrains]

I switched my Raspberry Pi 4 recently to a 2011 Mac Mini with an SSD when using JMRI. With the money I sold the pi for I was able to get the Mini and SSD with some money left over. I use DCC-EX as well. Render times on the panel were horrible. Should also mention I was running the Pi 4 (4 GB RAM) in an Argon case with fan and heat sink and using an M.2 Sata drive.

[@WirenwoodModelRailway]

Thanks Brian - it's encouraging to know that there were no potential improvements with a heatsink and fan. I think the Pi is a great entry point for JMRI (or it was when it was more affordable) but needs to come with a caveat along the lines of 'it's great for the basics but look elsewhere if you're going down the automation route'.

[@BriansModelTrains]

@@WirenwoodModelRailway I agree. I use raspberry pi's throughout my house all doing different jobs. According to sources new units should be available in North America by Fall 2023 at regular prices. It's crazy what they sold for lately. Your automation is incredible. Thank you for sharing.

[@WirenwoodModelRailway]

Me too! I have a few of them running Snapcast for synchronised house-wide audio which i love, and another 4 up in the loft (including the rejected JMRI one) running those static cameras. They're such useful, versatile little devices. Thank you for the kind words! Chris.

[@pierre-de-standing]

This is difficult to put without being critical but bearing in mind that you have a PC there, I'm surprised you didn't use it from the outset and when I discovered your channel I had assumed you were. JMRI will work via ethernet to attach to a command station, and I suspect the Pi (from personal experience of using it to monitor systems) is not really up to the task of a sophisticated layout. Another aspect to consider is that the quality and length of the bus and the number of nodes will affect the baud rate of RS485. I doubt that you are hitting the limits, but maybe still worth considering? I use an old Dell laptop (i5 and 8GB RAM) running linux for JMRI connecting to a Z21 via ethernet although I might go to DCC EX and sell the Z21. The DCC EX recommendation is to use a Mega not an Uno as the Uno is at the limit of the memory when running DCC EX. You are sir a trail blazer, I take my hat off to you.

[@WirenwoodModelRailway]

Ha, thank you! Actually, right back this time last year when I started this layout, I was using an Arduino and motor shield. But the standard motor shield, mentioned in many of the YT 'get a command station for under ££' type videos, was woefully underpowered and could cut out with even just one loco running. So to be able to run a couple of trains at a time I switched back to the Pi and SPROG, which I'd used on my previous layout. Then, when it became obvious that the Pi wasn't going to cope with automation, that was when I started looking for alternatives and found the MOSFET based 15A board that I got connected up in this video. And it hasn't given me a single problem since! Interesting about the Uno and memory - there is noticeably a huge amount of source code that gets compiled and transferred for DCC+EX - if I start getting issues with the command station I'll try switching to a Mega - thank you!

[@aleopardstail]

IIRC with JMRI you can set how often the sensors are being polled Whats the Spec on the Pi4? (e.g. what ram?) you can stick a CPU and Ram monitor to show on the menu strip which should tell you if the beastie is struggling, if its not its something else

[@WirenwoodModelRailway]

Thanks Dale - I certainly haven't seen that option - you can set whether polling occurs, but not how often. Plus it's plainly a performance / capacity issue - I could ask it to poll 5 times per second but there's no guarantee that it would! It's a 4gb RAM Pi. I've been using the PC for about a week now and have to say it's a night and day difference from the Pi. I'm sad, I love the Pi, but it wasn't up to what I needed from it. sadly.

[@aleopardstail]

@@WirenwoodModelRailway pity really, suspect the issue is Java, but no getting away from it really for C/MRI there is am "output interval (ms)" setting, defaults to 250ms - its under "additional connection settings", what there isn't, and this is a real shame, is an option to set a polling interval for individual sensors. loving what you are doing though, trying similar here though on a somewhat smaller scale, not just because its N gauge but a 4'x2'6" layout to experiment on - very interested in the automation stuff you have done and how clearly you have shown it, a lot easier to see it done and explained than to work it all out :)

[@WirenwoodModelRailway]

@@aleopardstail Thanks Dale that's really useful - one of those things I'd seen but not registered what it actually was! As I move on to getting signal masts around the layout I've realised that I'll probably need more Arduinos. One thing that's crossed my mind is to have some Arduinos with no inputs at all - as CMRI won't poll a node that has no sensors attached. That should reduce the traffic a little. And thank you, that's very kind! That's the whole point, really, I think - there is little to go on on this subject, so I thought if I share my failures and issues, and how I go about trying to resolve them, it might help someone like me!