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
The bad news: my ESC (see “Kinetis Drone: Graupner ESC S3055 Failure“) for my Kinetis drone is still not repaired :-(. Anyway, I have plenty of other things to make for my drone project. One is to work on the remote controller:
Test Setup
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
Probably for cost reasons, the Freescale FRDM-K22F does not come with the micro SD card socket populated on the the board:
Freescale FRDM-K22F Board with no SD card socket
With a little soldering skills it is possible to populate the socket so the board can be used with a file system on it :-):
Using SD card with FRDM-K22F Board
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
In “Going to Mars: Building a DIY Eclipse IDE for ARM Embedded Microcontrollers” I described how to install an Eclipse based IDE for ARM, based on Eclipse Mars (4.5) and CTD (8.7). There are many great new features in Eclipse Mars which makes that switch worthwhile: the Launchbar:
Launchbar in Eclipse Mars
A dream is are now a reality: a really, really easy way to build, run/debug an application!
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 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 