Arm Mbed OS support forum

Is there a guide to using the online compiler

I am new and trying to use the online compiler. I have tried to compile for both a FRDM-KL05Z board and a NucleoL053R8 board. Neither board was recognised by the compiler even though it was selected in the top right hand corner of the compiler screen. I got a “Error: Target “NUCLEO_L053R8” is not recognized” error for the nucleo borad and a smilar error for the FRDM board. Nor could I find any way to see any header files whatsoever.

So, I tried importing the blinky examples from this page : “Importing and compiling the code - Quick start | Mbed OS 6 Documentation” This time I saw some documentation and a long list of header files. So far, so good. But would it compile, no not on you nelly !

Header files are essential to knowing what everything is called, I can only seem to find any by importing examples!

Surely I am doing something wrong, but I have so far found nothing in the documentation here that helps. So I am asking here for the location of the idiot’s guide to this world.

thanking you in hope.

Hello Pete,

  • some guide for Mbed build tools you can found here - Overview - Build tools | Mbed OS 6 Documentation
  • you can not see the content of MbedOS via OnlineCompiler, that is possible only via Github, off-line tools or ARM Keil Studio online (beta).
  • the headers what you saw in the tree of MbedOS via OnlineCompiler is obsolete and it is not maintained anymore. If you want to see the source, then just visit Github or just use the page what you linked above, that is the place of official documentations - Full API list - API references and tutorials | Mbed OS 6 Documentation
  • I tried import Blinky from Code | Mbed and from the link what you posted above and the compilation seems to be OK for FRDM-KL25Z | Mbed . For NUCLEO-L053R8 | Mbed is there the error “Error: Target “NUCLEO_L053R8” and that is because it is not supported target (because of low memory) under MbedOS6+ Development boards | Mbed
  • for L053 you will need older versions of MbedOS, probably 5.15.7 with bare metal profile or Mbed2.

BR, Jan

Thank you for the reply Jan, Do you prefer to be called Johnny? Thanks Johnny . It sets my mind to rest that it is because both boards are unsupported. No really my error after all. I seem to remember that the header files would appear there when starting a new project, but that was many years ago. Now I need to look at other IDEs since my boards are unsupported.

Your reply has certainly laid my mind to rest over my difficulties and I thank you for it.


Hello Pete,

  • As Jan said, you can still used the online compiler + Mbed 2, though it is deprecated (no new drivers) by Mbed team. Since there is no RTOS included in Mbed 2 by default it’s easier to start with for beginners.

  • You can find the related Mbed 2 documentation in the Handbook and the Cookbook. There is also a “Help” tab in the online compiler (the last button on the toolbar).

  • When you create a new program make sure you select a Mbed 2 template, for example “Blinky LED Hello World”. Templates with a name including “-os” usually create a Mbed OS 6 program which includes RTOS by default and demands bigger RAM than is available on your current target boards.

Pete, the names John(En) and Jan(CZ/SK) is same but in different language so it does not mater :slight_smile:

However, maybe I wrote it not good for understanding but from my understanding and testing (I don’t have this piece of hardware, so I can’t physically try it out) the KL25Z you can use with MbedOS6+, that mean with latest version of MbedOS - maybe bare metal profile.

BR, Jan

Thank you Zoltan. I think I would prefer Mbed 2, I am still only learning to crawl let alone run or play sport.
I was attempting from scratch in the online compiler. I had come across the manuals telling me I needed to tell it that is was to be a “bare metal” programme in s new(new to me) type of file of which I have not one iota of a clue about. Your suggestion of using a template is one that I like. I will need to copy the header files, including the library too for the day when Mbed2 is withdrawn.

Thank you once again Zoltan, now to bury my head in the handbooks and examples and attempt to learn the ways of the programming world.


Thanks Jan

Zoltan had suggested that I can use Mbed and I think I will go down that root until I am far more familiar with Mbed site, philosophy and programming in general. I do have a KL25Z which I can now see I can use as part of my learning to get familiar.