As mentioned in an earlier blog post this year, hardware debuggers are the premier class of embedded debugging tools. However, until today, there were only very few relatively expensive tools around supporting the debugWIRE interface that is used by the classic ATtinys and a few ATmega MCUs.
The good news is that now you can turn an Arduino UNO, Nano, or Pro Mini into a debugWIRE hardware debugger that communicates with avr-gdb, the AVR version of the GNU project debugger.
The featured image of this post is by Albert Guillaume – Gils Blas, 24 décembre 1895, Public Domain, Link
When you develop a tool for a protocol that is undocumented, it is not surprising that you will encounter situations you will not have be anticipated. This was exactly what I experienced developing the hardware debugger dw-link, which connects debugWIRE MCUs to the GDB debugger. Although a substantial part of the debugWIRE protocol has been reverse-engineered, I encountered plenty of surprising situations: Split personality MCUs, stuck-at-one bits in program counters, secret I/O addresses, half-legal opcodes, and more.
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The featured image of this post is is a comic from xkcd.com.
The above xkcd comic, which is titled Debugger, alludes to the concern that when you try to apply a particular method to itself, you might not get what you asked for. Turing’s Halting problem is a very famous example of this, i.e., you cannot algorithmically decide whether an algorithm terminates on an input. So, does that issue apply to debuggers as well? In particular, I asked myself whether it makes sense to debug the hardware debugger I am developing with itself.
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The featured image of this post is based on a picture by TheDigitalArtist on Pixabay.
Link-time optimization (LTO) is a very powerful compiler-optimization technique. As I noticed, it does not go very well together with debugging object-oriented programs under GCC, at least for AVR MCUs. I noticed that in the context of debugging an Arduino program, and it took me quite a while to figure out that LTO is the culprit.
Continue readingDebugging is twice as hard as writing the code in the first place. Therefore, if you write the code as cleverly as possible, you are, by definition, not smart enough to debug it.
This quote is very much to the point, in particular, when one starts to create overly complex implementations. Keep it simple, stupid!
The featured image is by Hebi B. on Pixabay
How can you use a stub in order to squash your software bugs? This blog post shows how to arrive in 7 easy steps at a working debugging solution using a gdb-stub for some 8-bit AVR MCUs. The only additional hardware you need is an ISP programmer in order to burn a new bootloader (well, if you are satisfied with a very slow-running program, you do not even need this).
Featured picture: OpenClipart-Vectors on Pixabay.
One has to add to the title (quoted from a tweet by Filipe Fortes) that the detective suffers from memory loss. Otherwise, the case could be solved easily. Similarly, with debugging: If I only knew what nasty things I have hidden in the source code, I could just remove them – but I simply do not know. In this blog post, we will have a look at what kind of tools one could use to find the skeletons hidden in the closet.
When something goes south, it is not always the programmer who is to blame. It could also be the hardware (resp. the electrical engineer) that might be responsible. Note, however, when you are developing your system as a hobbyist, you are both: the electrical engineer and the programmer (so you always can blame yourself). In this blog post, we will take a look at some of the things that can go wrong on the hardware side.
Featured image: Courtesy of the Naval Surface Warfare Center, Dahlgren, VA., 1988. – U.S. Naval Historical Center Online Library Photograph NH 96566-KN
Be honest: When did you last time designed a system that worked right from the start and did not need any corrections? Right, that was probably a long time ago – or never. People usually spend a lot of time in identifying and correcting errors, colloquially called bugs. In this blog post, I will give you an overview of different forms of bugs and what you can do about them.
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