To facilitate student learning and preparation for the exams, I passed today a collection of exam questions with solution hints to the students. And as well why I’m *not* asking simple ‘true or false’ questions my exams:
The Right Way to Answer True or False Questions
š
There is a really annoying issue with using command line tools on Windows: the maximum length of the command line passed to cmd.exe is 8192 characters (see http://blogs.msdn.com/b/oldnewthing/archive/2003/12/10/56028.aspx). So you think this is not a problem for you, as you would not pass such a long command line to cmd.exe (the DOS shell under Windows)? Well, if you are using Eclipse (as I do) which generates make files (which is the normal way), then the cmd.exe very likely is involved to call the compiler/linker/etc, indirectly with the usage of make.exe. Compiling files is usually not a problem as it does not hit that 8192 limit. However, it is likely that link phase will end up with an error:
Error in the Problems View
If you have such a problem, there is a solution ….
For a home automation project I need to know the room temperature and humidity percentage of the room air. Adafruit has an inexpensive DHT11 sensor fromĀ http://www.aosong.com which I decided to use for that project.
Test Setup for DHT11 Sensor
If you are designing your own board for the Freescale FRDM boards, then having the matching PCB design files is a good thing to have. I have posted this week an Altium contribution on GitHub for the FRDM headers (see “FRDM-KL25Z Arduino Headers with Altium“). And here there is yet another contribution I received from [Darren]: the FRDM-KL25Z board in Altium :-):
FRDM-KL25Z in Altium
Eclipse with GDB is great: it comes with a graphical front end for debugging. But sometimes it is all about to download a program. Is it really necessary to launch an IDE like Eclipse to program or quickly debug a board? With the GNU Debugger (GDB), the answer is ‘no’: GDB comes with a command line debugger which is designed exactly for this: providing a command line interface for programming/downloading and debugging, bypassing any GUI (Graphical User Interface).
Combination of GDB Debugging Probes and Boards (P&E, Segger and FRDM-KL25Z)
In case you are using Altium to design your boards, then this one might be useful for you:
FRDM-KL25_Footprint
OpenOCD is an open source and free-of-charge debugging solution, which is a great option here at the University of Lucerne, as students do not need to buy an expensive debugging probe. Still, I recommend to buy professional probes like the P&E or Segger ones, as they are worth every (Euro) cent. But for a ‘zero’ budget, OpenOCD with CMSIS-DAP is something to consider. And with Kinetis Design Studio using the GNU ARM Eclipse Plugins, OpenOCD is not that hard to be used. And because both Freescale and GNU ARM Eclipse offer OpenOCD Windows binaries, that connection method is in the reach of Windows users too.
FRDM-KL25Z with OpenOCD Debug
There is a new release of the McuOnEclipse components available on SourceForge, with the following main changes:
SourceForge McuOnEclipse
This happens several times for me: I have a board running for a while (even for days), and then it crashes or is stuck somewhere. Yes, I usually use a watchdog do recover from that situation. But it would be good to know and debug the problem. With CodeWarrior I had the functionality in the debugger to ‘attach’ or ‘connect’ to a running (stuck/crashed) board. However, with Eclipse/Kinetis Design Studio/GDB this is a different debugger, and not possible. At connection time with the debugger the target does a reset, so I don’t know any more where the application crashed. But now I have a solution, at least with the Segger GDB :-).
Debug Hard Fault Attached Target
