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A little fail-safe filesystem designed for microcontrollers (2017)

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Re: A little fail-safe filesystem designed for microcontrollers (2017)

#21
post #2

I am curious - does anyone have some feedback from using the mbed ecosystem? I have generally shied away from using too much vendor middleware but it does look like there are a lot of useful libraries.

I have a tiny bit of experience with it. I found it hard to keep track of which libraries worked with each other or with my particular microcontroller (particularly anything involving networking), but it was probably just my own ignorance.

Re: A little fail-safe filesystem designed for microcontrollers (2017)

#22
Seems well thought through, but the concept of putting a general-purpose file system on an embedded microcontroller is a common mistake.

These are single-purpose systems, you don't need to use filenames and have POSIX semantics, you typically just need to put your data into a circular buffer on FLASH. The circular buffer (with checksummed elements) will take care of bad-block management and wear levelling for you.

I've seen this far too often, filesystems are not ideal for this class of system.

Re: A little fail-safe filesystem designed for microcontrollers (2017)

#23
post #4

Earlier quoted context omitted.

I would also love to hear replies to this. I used mbed in the past and have been fairly dissatisfied with it for two reasons: It uses c++ for the sake of using c++ instead of leveraging the extreme bonuses c++ provides over using c for embedded. For example, it tends to use dynamic memory allocation heavily, doesn't make use of unique/shared pointer, doesn't use templates properly (if at all) in places it would be id…

Your criticism seems a bit idiosyncratic, to put it kindly. So it doesn't use the flavor of C++ you prefer? Sure, but there's a lot of room for argument about whether shared_ptr or template-instantiation bloat would be good choices for an IoT-level embedded system. Similarly, the fact that it doesn't use cmake seems like more a matter of preference than of actual suitability. As for being supported by ARM, well hey,…

The EULA for mbed says "ensure that they are licensed for use only as part of Software Applications and only on microprocessors manufactured or simulated under licence from Arm" https://os.mbed.com/eula/

It is confusing though as the code mostly appears to be Apache, not sure if it is just parts that are constrained by the EULA, but it is clearly not intended to be ported to RISC-V or MIPS or whatever.

Re: A little fail-safe filesystem designed for microcontrollers (2017)

#24
post #21
post #2

I am curious - does anyone have some feedback from using the mbed ecosystem? I have generally shied away from using too much vendor middleware but it does look like there are a lot of useful libraries.

I have a tiny bit of experience with it. I found it hard to keep track of which libraries worked with each other or with my particular microcontroller (particularly anything involving networking), but it was probably just my own ignorance.

My experience with it was all the packages for the platform I wanted to use were broken.

Re: A little fail-safe filesystem designed for microcontrollers (2017)

#25
post #19
post #2

I am curious - does anyone have some feedback from using the mbed ecosystem? I have generally shied away from using too much vendor middleware but it does look like there are a lot of useful libraries.

I worked with mbedTLS on a desktop/mobile project a couple of years ago. I'd previously used OpenSSL, and I wasn't very impressed, but mbedTLS seemed OK: easy to get it building with cmake, easy to get it building on Windows/OS X/iOS/Linux, no actual I/O in the library. I remember finding integration with libuv a mite annoying, as mbedTLS is rather pull-minded, and I didn't find the documentation for the I/O callback…

> (Would not use OpenSSL again.)

Reminds me of someone using this gif to describe working with OpenSSL.

https://imgur.com/gallery/ikBZF82

Re: A little fail-safe filesystem designed for microcontrollers (2017)

#26

Earlier quoted context omitted.

Your criticism seems a bit idiosyncratic, to put it kindly. So it doesn't use the flavor of C++ you prefer? Sure, but there's a lot of room for argument about whether shared_ptr or template-instantiation bloat would be good choices for an IoT-level embedded system. Similarly, the fact that it doesn't use cmake seems like more a matter of preference than of actual suitability. As for being supported by ARM, well hey,…

The EULA for mbed says "ensure that they are licensed for use only as part of Software Applications and only on microprocessors manufactured or simulated under licence from Arm" https://os.mbed.com/eula/ It is confusing though as the code mostly appears to be Apache, not sure if it is just parts that are constrained by the EULA, but it is clearly not intended to be ported to RISC-V or MIPS or whatever.

That EULA is specifically for the ARM RealView compilation tools, which are proprietary AFAIK.

You don't need any EULA to use any of Mbed's stuff, it's all Apache licensed and can use any compiler.

Re: A little fail-safe filesystem designed for microcontrollers (2017)

#27
post #2

I am curious - does anyone have some feedback from using the mbed ecosystem? I have generally shied away from using too much vendor middleware but it does look like there are a lot of useful libraries.

mbed is great for prototyping. It's basically the Arduino system you would have gotten if Arduino was developed by people who mostly already know what they are doing instead of learning as they go.

Lots of libraries for various sensors and other applications, so if you do early stage development on hardware you can quickly throw prototypes together and not need to deal with sorting through a lot of mediocre Arduino stuff.

YMMV on keeping it for production use. Some parts of it should be fine for some applications. Other things not. I've run into issues with things like threads and timers not always working right for every library, but really that's par for the course on a system of libraries that diverse, and supporting so many different chips.

Re: A little fail-safe filesystem designed for microcontrollers (2017)

#28
post #4
post #2

I am curious - does anyone have some feedback from using the mbed ecosystem? I have generally shied away from using too much vendor middleware but it does look like there are a lot of useful libraries.

I would also love to hear replies to this. I used mbed in the past and have been fairly dissatisfied with it for two reasons: It uses c++ for the sake of using c++ instead of leveraging the extreme bonuses c++ provides over using c for embedded. For example, it tends to use dynamic memory allocation heavily, doesn't make use of unique/shared pointer, doesn't use templates properly (if at all) in places it would be id…

There is a difference between mbedOS and the support libraries which can all be used independently of their monolithic system. Modern C++ is not supported by some commercial compilers so you get lowest common denominator in that case but that is irrelevant to the core libs all implemented in C.

Re: A little fail-safe filesystem designed for microcontrollers (2017)

#29
post #19
post #2

I am curious - does anyone have some feedback from using the mbed ecosystem? I have generally shied away from using too much vendor middleware but it does look like there are a lot of useful libraries.

I worked with mbedTLS on a desktop/mobile project a couple of years ago. I'd previously used OpenSSL, and I wasn't very impressed, but mbedTLS seemed OK: easy to get it building with cmake, easy to get it building on Windows/OS X/iOS/Linux, no actual I/O in the library. I remember finding integration with libuv a mite annoying, as mbedTLS is rather pull-minded, and I didn't find the documentation for the I/O callback…

mbedTLS is mostly nice but it does suffer from some poor coding practices like large buffers allocated on the stack.

I would warn anyone to stay away from Cypress/Broadcom's WICED OS which has a modified version of mbedTLS with foolish changes to the API that makes porting code extremely challenging.

Re: A little fail-safe filesystem designed for microcontrollers (2017)

#30
post #2

I am curious - does anyone have some feedback from using the mbed ecosystem? I have generally shied away from using too much vendor middleware but it does look like there are a lot of useful libraries.

yes. i found a bug in the gcc export along with a dozen others. mbed devs hemmed and hawed about it for 6 months until they convinced themselves it's not a bug. I dropped mbed after that, switched that project over to Arduino.
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