Tag Archives: Building

About build tools, make files, compiling and linking.

Reducing Code Size with gcc and EWL

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If you have not noticed: the final CodeWarrior for MCU10.3 has been released on the Freescale web :-).

It comes with a few changes compared to the 10.3beta release, and one is about the library configuration. I noticed that new projects created with the wizard are around 4 KByte larger than I expect them to be. For example my rather simple application below uses 8 KByte of code, where my expectation would be in the range of around 4 KByte:

   text       data        bss        dec        hex    filename
   8644         24       1108       9776       2630    Freedom_2x16_HTA.elf

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Debugging Hard Faults on ARM Cortex-M

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It is as bad as this: my application stopped in an unhandled interrupt service routine:

Cpu_Interrupt
Cpu_Interrupt

That does not tell much. I’m using Processor Expert generated code, and with this all my ‘unhandled’ vectors are pointing the same handler:

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Thumbs up with Assembly on ARM Cortex

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Sometimes it is necessary to write an interrupt service routine in assembly language. This is the case as well for the ARM Cortex-M0+ which is found in the KL25Z on my Freedom board. But there is something important about the ARM Cortex architecture: Thumb Mode.

Thumb mode the ‘ARM way’ to reduce the code size with a reduced (16bit wide) instruction set. The ARM architecture can implement a ‘mixed’ mode, on a function level. To distinguish between ‘normal’ ARM functions and ‘thumb’ functions, the processor is checking if the LSB (Least Significant Bit) of a function pointer (or function call destination) is set. So a jump address of 0x410 is for a ‘normal’ function, while a function jump to the address 0x411 (even if the function is located at the address 0x410) denotes a ‘thumb’ function.

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Optimizing the Kinetis gcc Startup

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The GNU gcc tool chain integration in CodeWarrior/Eclipse MCU10.3 has a nice feature to show the code and data size of my application after linking (see this article how to enable this). So if I create an ’empty’ project with the wizard, get the code and data size without consulting the linker map file:

Console View with Code and Data Size

Console View with Code and Data Size

But wait! 2604 bytes of code for almost doing nothing? That’s not what I want! There are ways to get that puppy much, much slimmer. Down to 284 bytes :mrgreen: .

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Defining Variables at Absolute Addresses with gcc

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Many compilers offer a way to allocate a variable at an absolute address. For example for the Freescale S08 compiler, I can place my variable at a given address:

unsigned char buf[128]@0x2000;

This is very useful (and needed) e.g. if the hardware (like USB) needs a buffer at given address. The advantage of the above (non-ANSI and thus not portable) syntax is that I can define a variable at an absolute address, without the need to allocate it in the linker.

I wanted to do something similar with gcc for Kinetis/ARM, and searched many forums on the internet. Obviously, I’m not alone with this question. The solution I have found comes close to what I use e.g. for the S08 compiler.

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Foreign Characters for the Eclipse Build System

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Having a problem with Eclipse and building files with foreign characters in the file name? If you are developing software, then read and follow this advice:

“Do ❗ NOT ❗ use foreign characters in file names, paths or for anything else!”

What I mean with ‘foreign characters’ are things like éöüàäü, or simply anything which is outside the 7bit ASCII or Windows-1252 code page table, even if they are allowed by the file system of your operating system (e.g. Windows).

Or in other words: only use these characters for file or directory names:

abcdefghijklmnopqrstuvwxyzABCDEFGEHIJKLMNOPQRSTUVWXYZ1234567890_

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Speeding up the Debug Launch in CodeWarrior

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Whenever I do a debug launch in the Eclipse based CodeWarrior, it takes some time until actually I’m ready to step through my code on the target. Yes, a good part of that is by Eclipse. But another part is that Eclipse helps me to do stupid things (which is a good thing). But say if I know what I’m doing, I could remove some of that safety belts and still doing fine. But only if I know what I’m doing.

A good indicator where Eclipse is spending time is to have a look in the Progress View:

Progress information during launch

Progress information during launch

It shows an interesting information: ‘Build before Launch’….

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Copy my CodeWarrior Project

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I have a project working, and then I want to do a copy. Unfortunately, this is not as simple as it should be :-(. In order to copy a project with all the settings, some knowledge about the internals of the project structure is required, which is the topic of this post.

In “Copy my Project” I was using a ColdFire V2 project which is not an easy case, as is using a Target Task to flash the microcontroller. Fortunately, all other targets in CodeWarrior for MCU are *not* using target tasks :-). With little help and preparation, a copy a project is not that difficult to do.  I’m showing how to do this with the FRDM-KL25Z project I have created in this post.

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Removal of Processor Expert for a Project

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Yes, I’m using Processor Expert *a lot*. But there might be reasons to go without it. Because then I really want to do it the hard-hard-hard core way. Or maybe because I have configured my system, and want to freeze my code. And nothing prevents me to do it ‘my way’.

In any case, it is easy to transform a CodeWarrior Processor Expert project, and then decide to remove that technology from it, and go further with the ‘traditional’ technology.

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A Library with ARM gcc and Eclipse

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When I create a new bare-board project with the Eclipse based CodeWarrior 10.3 for my FRDM-KL25Z board and GNU gcc, then the ‘Library’ option is grayed out:

Library Option in New Project Wizard

Library Option in New Project Wizard

This does *not* mean that libraries cannot be built :-). In fact it is very easy to do this with the GNU tools and Eclipse, and here is how….

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