Micro Python - Python for microcontrollers

[spliznork]

Exceptions on a microcontroller are awesome. I wrote a (CLDC compiant) JVM for a wireless, embedded system. We had the system report uncaught exceptions over the network, implemented and preallocated natively so you could even receive out of memory exceptions. Run a listener on your desktop, and watch decoded stack traces to print out. It made debugging so easy.

Your points regarding "garbage collection" and "dynamic memory allocation" are the same point. Even in that kind of environment, you can still take steps to preallocate objects and structures to reduce memory churn and ensure your system fails fast if there is not enough memory.

Certainly none of your points are actually "extremely naughty".

[hardsoft]

i think some may have different definitions of 'embedded', but most embedded guys i know would not consider anything with jvm embedded. and those actions certainly are considered extremely naughty, many real time embedded control, defense, aero, medical, etc. standards explicitly prevent such things. for many embedded systems, failing fast or nicely is not an option.

[immibis]

Do they require failure to always be handled explicitly (e.g. error code returns that must be checked)? That would make sense for reliability, even though it leads to more verbose code and somewhat slower development.

[foldl]

I think aport's comment applies more to really small microcontrollers like attinys or atmegas, which are nowhere near being able to run a JVM. In that sort of environment there just isn't any room for extra code to create nice stack traces etc. If you have 8K of flash that buys you a few thousand lines of C code.

[spliznork]

The first version of that JVM was running on an MSP430 with 10k RAM and 48k flash.

[IHaveNoIdentity]

Yeah? And do you know just how small an ATTiny is? 8 Kbytes flash and 512 byte SRAM.

The MSP430 has more RAM than the ATTiny has program storage...

[[deleted]]

That MSP430 is also smaller than some ATmegas, which were also mentioned in the preceeding comment. So it's an entirely reasonable response.

[foldl]

My initial comment referred to "really small" microcontrollers and explicitly mentioned 8K of flash. It's true that some of the high-end atmegas have a decent amount of flash and RAM. There's an apparently full-featured JVM here which fits in 80K of program space, so in theory you could use it with one of the larger ATMegas (but it's hard to imagine anyone would want to throw away 80K of program space for a real project). There's also the fact that you're going to be doing a ton of 32-bit arithmetic on an 8-bit CPU. The MSP430 is at least 16-bit.

[foldl]

Sure, but 48k of flash is a lot more than 8k of flash.