Readers of my blog know: I’m not a fan of printf(), and I think for many good reasons. Still printf() is widely used, and the GNU gcc tries to optimize things. This is observed with a simple example: If I’m writing
printf("a");
Then the code produced (ARM Cortex-M0+ with GNU ARM Embedded 4.9 2015q2 gives:
movs r0, #97 ; 0x61 bl 0xa98
Instead of calling printf(), it is calling putchar()! Why is that?
PutChar instead of Printf
One of the most important aspects for developing complex realtime applications is get insights into what is going on the target. Segger just has released a free tool which gives an incredible useful insight view and visualization:
Segger System View for FreeRTOS
This tutorial is about how to create a lwIP project with FreeRTOS using the Kinetis SDK V1.3.0 with Kinetis Design Studio on the Freescale FRDM-K64F board.
FRDM-K64F Board with lwIP running
How about to use the Freescale FRDM-KL43Z board (see “Unboxing the Freescale FRDM-KL43Z Board“) to play a Tetris game?
Sometimes I need to link an object file (e.g. bootloader.o) to my application, and I do not want to build it, or I do not have the sources to build it. There is a simple way with the GNU ARM Eclipse plugins to link extra object files:
Other Objects for GNU Linker
Many tool chains and linker are able to produce S19 files, such as with the GNU tools it is the ‘objcopy‘ which does this job (see “Binary (and S19) Files for the mbed Bootloader with Eclipse and GNU ARM Eclipse Plugins“). But these tools usually cannot handle the special cases. For example on the Freescale Kinetis K64F my serial bootloader (see “Serial Bootloader for the Freedom Board with Processor Expert“) had a problem with these lines in the S19 file:
Not aligned S19 file entries
Some of my robotics projects take a rather long time do a full build. When I developed applications with Visual C++ on the host, using precompiled headers gave me a big boost in compilation speed. I was looking for the same in similar with GNU and gcc, and as expected: gcc does support precompiled headers too. And indeed, I was able to cut down compilation time by 30% :-). So this post is about how to use gcc with precompiled headers in Eclipse/CDT to give my builds a boost.
using precompiled header
It has been a while since I published my ‘build my own DIY IDE’ (see “DIY Free Toolchain for Kinetis: Part 1 – GNU ARM Build Tools“). I have used that approaches in my classes successfully. Now a new semester is coming up, so time to update the instructions using the latest Eclipse IDE (Mars) and tools (GCC ARM Embedded (launchpad) with GNU ARM Eclipse).
Eclipse Mars Splash Screen
I need to program several boards with a firmware: a number too small for serious batch/factory programming, but a number too high doing this with the debugger. I want this:
Need to program a few boards…
I have published a Sneak Preview how GNU gprof profiling looks for an embedded target ARM Cortex-M in an earlier post:
This tutorial explains how to profile an embedded application (no RTOS needed) on ARM Cortex-M devices with GNU gprof. Additionally I explain the inner workings to generate the data necessary for gprof.
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MCU on Eclipse 