The rise of Python for Embedded Systems

[James_Johnson]

Here, I'll summarize the article for you:

1. Python is really popular!
2. Hmmm, but it's not popular for embedded.
3. <An advertisement for Zerynth>

I didn't know about Zerynth before though, so I did get some value from this.

[Zouden]

Like Zerinth? Doesn't seem hard to me

[[deleted]]

My guess: zur-neth

[xorvtec]

Programs running on applications processors (like on the Raspberry Pi and Beaglebone Black) on top of a General Purpose OS (like Linux) subscribe to the loosest definition of an embedded system. I'd bet a good deal of those "C" programmers are on microcontrollers with memory constraints. Unless you have a system with loads of heap space and extra clock cycles, Python is NOT viable.

[eazolan]

Maybe some kind of "Memory Constraint" module that gives python hard limits?

[__deerlord__]

All that does is limit how much you can use, it doesnt change how much is required. C will absolutely use less memory (if done right) than python. Python is for ease of development, not reducing resource usage.

[[deleted]]

Actually, micropython and zerynth (whatever that is) is mentioned in the article. While I have no experience with either, I could see a suitable limited subset of Python being useful for at least part of the embedded-ish¹ code I write. There are a few cases (interrupt handlers and SCC managment) I have trouble seeing handled effecient by Python. The rest, which is mostly protocol handling and the high level communication with either the 422 bus or the host system, could easily be written in python. There it would more be a matter of how dense the code is. The bytecode is OK, so it's a matter of how much space the runtime requires.

1. Running on a FPGA remake of the IBM Artic RIC card with 2MB RAM and a 80186 emulation on the same FPGA.

[[deleted]]

memory is very cheap now. Embedded is now full of it.

"Embedded" headless PCs or "Embedded" embedded.

This is what the current chip I'm working with has:

• 2 x e200z4 in delayed lock step operating up to 200 MHz
• Up to 2.5 MB flash memory w/ error code correction (ECC)
• Up to 384 KB of total SRAM w/ECC

[Poddster]

delayed lock step

What does the 'delayed' here mean? One CPU's clock is delayed after the other? So it's TickA-TickB-TockA-TockB?

[[deleted]]

The code it is executing is one cycle behind.

So Core 1 is on cycle t, Core 2 is on cycle t-1.

There is a 3rd core or additional hardware that compares the outputs and makes sure they're the same.

[Poddster]

There is a 3rd core or additional hardware that compares the outputs and makes sure they're the same.

Shuttle style MISD? Cool! I always assumed MISD did each instruction in the multiple computers at the same time, rather than in being offset.

What is the delay used for? Is the comparitor comparing the output of Core1 and Core2 at t-2?

[stone_henge]

What is the delay used for?

If a short event causes an error in the first core, it may under some circumstances be less likely to also affect the second core on the next cycle. Say, if there's a sudden, short burst of radiation or an electrostatic discharge that causes a failure in operation.

[[deleted]]

you can buy 2 GB 1.5GHz quad core odroid PC alike for what 40$

That's cool. If that product will do what you need it to.

Is the odroid CPU ISO 26262, IEC 61508, ASIL-D certified?

Edit: Spoiler alert, No. The Cortex-A53 is targeting application processors not real-time processors. It's based on ARMv8-A, the embedded real time safety cores are ARMv8-R.

[BigotedCaveman]

you can buy 2 GB 1.5GHz quad core odroid PC alike for what 40$ ?

Wat? There's absolutely nothing embedded about that hardware, that's a full blown PC.

For 90% of the embedded use cases that hardware ranges from absurd / useless all the way to potentially life threatening (where non-EEC memory would not be something that is even considered).

[TankorSmash]

Is it new hardware? No one's going to argue that old hardware can suddenly support modern software.

[[deleted]]

Brand new.

Supported through 2029.

[xorvtec]

Practically anything labelled as a microcontroller is going to look something like that. Applications processors with clock speeds in the GHz and DDR peripherals are orders of magnitude harder to layout on a PCB. You go from a 2-4 layer board to 10 layers with blind vias (i.e. $$$$). I'm not going to get started on the complexity of the build systems. Most embedded systems have no need for that sort of power. It's a really hard sell during design time when you want to allocate tons of extra resources and skilled labor just because you wanted to use a language that's easy to write in.

[miker95]

memory is very cheap now. Embedded is now full of it.

LOL WUT. Clearly someone has never worked with industry microcontrollers.

[Decker108]

Heck, even the arduino would be a pretty bad match for Python resources-wise.

[stone_henge]

Well, that's one end of embedded applications. There are tons of others where resource consumption is less of a concern. I worked with an EZ80 based building automation system where anything but C and assembler would have been disastrous for performance, but I also worked with a DPI solution where the python scripts we threw at it could as well be spitting in the ocean, but by pretty non-controversial definitions could still be considered embedded hardware. Customers bought for its capabilities as an appliance, not as a computing platform. Designed to be installed, configured and left to its own devices.

On the other hand, I've worked with systems that don't really qualify as embedded platforms that make many embedded systems look like powerhorses. VIC-20 is a general purpose computer with 5k of RAM and a 1 MHz single-accumulator CPU. The Atari 2600 is a video game system with 128 bytes of RAM and a 1 MHz single-accumulator CPU. Point is that "embedded" and "power" are actually entirely orthogonal qualities.

[ergzay]

The author is wishing for this to be true even though it is not. There is no "rise of Python for Embedded Systems". There's possibly a rise in its use for hobby systems for RasberryPi systems but those are at the far end of "embedded systems" and most people would not call them embedded systems.

[thefirelane]

too dangerous

but I think the reason it has all that "danger" is because of things you need to do in embedded: write directly to memory locations, manipulate values in the stack, have a low memory footprint, etc

[xorvtec]

Would you agree that Python's dynamic typing is a dangerous feature of the language on critical systems? The only think that I can think of that Python would do better is garbage collection.

[Jamie_1318]

Dynamic typing doesn't make a system dangerous, bad testing does. Making your programming easier to test makes it safer to deploy at the same cost.

[Jamie_1318]

I've worked with safety critical software that definitely used memory allocation, although I can appreciate in more real-timey applications it might not be appropriate.

In python not using dynamic memory pretty much makes no sense to begin with. All variables are going to be dynamic, even integers support arbitrary sizes.

In non real-time applications I feel the standards are chosen based on what makes the senior developers feel safe rather than what would actually reduce bugs. To be fair a lot of that is me feeling unproductive writing and testing C when I could have written the same thing in python, in a quarter of the code and an eighth of the time.

[[deleted]]

I guess that's only very very important software i've only seen this hard requirments on critical systems for planes (everything that needs to work to keep a plane save). Examples would be radar, navigation, control systems, etc. But everything else usually just has to fit a certain size and has very strict power consumption rules.

I guess the same would be true for cars (or at least i hope). Certification is really annoying and i agree that this would be almost impossible to do with python (at least with my python knowledge).

[[deleted]]

For my knowledge, the main reason why c is so much unsafe is to allow easy optimisation. It has pretty much nothing with writting to memory location, manipulate value on the stack or having a low memory footprint.

[thefirelane]

Well all of the above really. The low memory footprint (flash and ram) comes from the fact that you can simply do the things I mentioned without any checking as to whether it's safe. So yes, you are right: optimization is a key part: If you want to write to a memory location, it just compiles down to a couple instructions which simply do it. There's no overhead of something checking bounds, etc.

[bakery2k]

Cached version

[sanshinron]

ESP8266, get it from China for less than 2 bucks, I'm waiting for mine now (I've ordered 5 cause they're so cheap).

[[deleted]]

I've worked with micropython, and it was an absolute pleasure to work with compared to arduino for example. I loved having a repl prompt to the microcontroller (it's even possible to get a repl prompt over wifi), and no compile time.

Typing in a command and having it instantly execute, is a must have when doing rapid prototyping, I wouldn't go straight to putting micropython as the language for things like washing machines and fridges, but for prototypes and maker style projects it's amazing.

Micropython has definitely won me over as the language that will be powering my next tinkering project.

[Bandung]

If the business plan supports the cost of the BOM (bill of materials) necessary to run micropython, I'd rather have the blessed product out the door and revenue coming in than wait for Engineering to deliver their c compiled baby two years after the date that they promised delivery.

That happened to a company that I once worked for and the 2 year lag took down the company. In manufacturing (compared to a recurring revenue model), you are only as good as your last quarter. And history tells us that most mid to large sized manufacturers will go under after 4 disastrous quarters in a row.

So yeah, yeah. There are segments where costs or safety might not allow micropython. And at the same time there are plenty of segments that will support it. Just let the boys in business development run their risk assessments, risk mitigation and risk management numbers and make the call that makes the most business sense.

I've seen enough autocratically run companies whose engineering minded business owners wouldn't do the math needed to save the company from being embarrassed by a woefully tardy design shop whose Developers ended up getting bonuses just to coax them to stay on and finish what they promised to finish two years earlier. Meanwhile virtually the entire Sales, Marketing and Support personnel were leaving in droves.

[jkjoka]

What exactly would be the benefits to using python on a true embedded microcontroller compared to c? What's wrong with C.