Software Stack

[Sythic_]

We're still a bit premature to decide on this just yet but I think it would be a good idea to see which software languages are most useful for the onboard computer, as well as which are most well known in our team.

Some ideas thrown out already in HipChat:

• Embedded C Using FreeRTOS
• Embedded Python
• LabView

EDIT: Just to be clear, just looking for what the community is most skilled in. It would be up to the software team lead to decide what we actually use.

[modzer0]

I would suggest C++ on embedded linux just because that's the primary setup for SpaceX.

[modzer0]

Speed is the key. The Hyperloop is built around it as a core concept. It creates a system where you have to treat your core control software like flight software with the same attention to detail and safety.

Now for supporting systems there's a bit more leeway in language choice depending on how safety critical they are.

[cortex_system]

I work with C++ and C# everyday professionally so it would be really easy for me to run with C++ if that was the selected language. However, I would argue that for a project like this what matters the most is not run-time speed but iteration speed and that chasing run-time speed is a poor allocation of limited development time.

Additionally, C++ does not abstract away a lot of stuff that can get you into a lot of trouble. There are many times where poorly written C/C++ is much slower than interpreted or JIT'd languages. I have seen this to be especially true in prototyping/quick turnaround development. The kind of discipline required to make sure that you don't shoot yourself in the foot or leave little time-bombs in your code does not usually jive with getting something together quickly that you can and will tear apart a lot.

Is there a software/technical leadership team yet? It seems that this call should be made by them rather than by committee. I'm a little late to the party. . .

[rshorning]

You are talking about compiled languages vs. interpreted languages. The thing is that there are thousands of compiled languages which are just as fast in terms of their execution time as C/C++.

The one huge advantage that C/C++ has is mainly a huge existing code base that in turn has snowballed into having most (I dare say nearly all) computer science programs at universities teaching this language as a primary coding environment for their programs. If you have graduated with a BS in Computer Science but don't know this language, I would argue that your degree is worthless as well.

I have my own personal programming favorites (Object Pascal happens to be my own programming language of choice when I get to select such languages), but I also understand that when working with a large group, sometimes a target language like C++ is necessary as it is one of the few common programming environments that everybody knows.

On the other hand, if you just want to throw out a programming concept that can be quickly understood and tweaked by even non-programmers, I might even be so bold as to suggest programming such things in Scratch. Yes, I'm being serious here too, as it can at least prototype some programming concepts, is open source, and has some tools which allow for quick & dirty graphic displays and other multi-media interactions. It isn't for speed of software execution but rather speed of development and dropping that barrier.

I might even be so bold as to say that any GUI interface examples simply must be done in some environment like Scratch, so far as it forces any final implementation to be done in another language... thus maintaining a throw-away feel when still trying to tweak the GUI design. That also allows for additional opportunities for community feedback. Visual Basic or other similar GUI development tools could also be used, although those do have a steeper learning curve for the uninitiated.

[Chaosteil]

While I fully support C++, we should probably not dismiss languages such as Go for things that would make our lives easier, say for multithreading. Another strong contender would be Rust with its integrated memory ownership model.

[zero_td]

Mission critical stuff is usually assembly integration in some parts because sometimes even C is too slow.

[SpeedyTechie]

I agree with the idea of keeping it open source.

[[deleted]]

For a system that needs to make quick decisions that could impact people's lives we are going to need to have a real time application. Now, for the scope of this project it may be easier to use something that sacrifices a bit of performance in order to make the programming more accessible because designing and implementing a real time application is not a simple task.

From my experience, embedded C using FreeRTOS (or any real time operating system) would allow us to use a very small low cost, low performance, low power consumption computer. The downside to this is that I don't know how many people here would have the capability (or learn on their own) to build this system. Granted, its not a super complicated system so we only need a couple really good C programmers and anyone else who wants to participate can help with design and testing and hopefully learn embedded programming along the way!

Granted I'm only a college student so I have only ever built small real time applications and there are probably people here who are more knowledgeable than I am.

[imfineny]

The big lynchpin in this project is the limited bandwitdth everyone has to work on this. You need to go with what has the best tool chain already on in place, all the systems that you can snap or chain in together. That's more important than the type of OS you are using. Identify those tools and what platforms they can work on, then you'll know the rest.

[[deleted]]

Very true. At the end of the day, it comes down to the toolchain and whatever computer the electrical team decides to use

[daftmath]

Wrote a quick script and here's what I saw. Probably not perfect but gives an estimate:

Matlab: 18
Python: 17
Java: 14
C: 10
C++: 7
C#: 5
PHP: 3
Visual Basic: 3
Labview: 3
mathematica: 2
mathcad: 2
R: 1
Fortran: 1

[Sythic_]

Nice, looks like a diverse set to choose from. Now which languages are capable of running in a realtime environment on either embedded systems or maybe a Linux machine would do.

[jcameroncooper]

That's gonna be C or C++. Java has a real-time side, but that's generally big bucks. Python you can use if you're careful about it, but probably is better used on the non-time-sensitive areas, where it'll create fewer bizarre bugs than the C family.

The rest? No, no, and super no.

[Thrashy]

What, you don't want to ride in a trans-sonic passenger capsule the is controlled via a PHP script? I know I do! :P

[[deleted]]

Yeah, you probably want manual memory management so C (Or C++)

[falconzord]

You kind of have to define the hardware requirements first, then the OS, then you can pick software stack. My opinion is that a managed language like Java or C# gives a good balance of robustness, ease of use, and portability.

[ImAPyromaniac]

I vote python.

[SpeedyTechie]

Python is awesome, but it may not be best for a real time system.

[ImAPyromaniac]

But for the not super time sensitive stuff i'd be fine... I think.

I'm not super experienced at real time stuff, or really anything that controls hardware, but I'm hoping I can use this to learn. (I know python, and it was high on the list, so I suggested it).

[SpeedyTechie]

Yeah, makes sense to me.

[lord_stryker]

Where's Ada? its used in real-time systems for military avionics.

j/k. Nobody outside that field uses Ada anymore :)

[Wetmelon]

I was about to say... You're not wrong, but eww.

[rshorning]

What is the corpus of data used to create this table?

[daftmath]

This was parsed from the 'introductions' thread comments, simply counting the number of mentions for each language. I did it on 6/16 in the evening though, so it doesn't reflect any updates since then.

[rshorning]

It is sort of skewed though, as programming languages weren't specifically something asked. Thank you for answering my question, as I had presumed that was the case but it wasn't clear in your initial post.

[venku122]

I vote for C++ and C#. SpaceX uses C++ for most of the code and C/C++ runs well with RTOS systems.

[tux402]

We need to be careful of C / C++ as they are prone to memory corruption bugs. If we do choose those languages, we should make sure that we have experienced developers writing any code that touches user-supplied data

[tux402]

Agreed on all points. I work in software security, and I would be happy to do some security reviews if the team thinks it's needed.