Tag: avr-gdb

Debugging 2.0

September 14, 2023 / nebel / 0 Comments

The featured image of this blog post is based on vector graphics by captainvector at 123RF.

What keeps people from using a debugger? Well, it is mostly that one has initial costs in terms of setting up the debugging environment and of learning how to use the debugging tool. Hopefully, the next iteration of my hardware debugging tool dw-link, which is able to debug classic ATtinys and ATmegaX8s, will somewhat ease that burden, in particular, because you can buy the accompanying hardware now at Tindie.

That’s One Small Step for a Man, One Giant Leap for a Debugger: On Single-Stepping and Interrupts

January 2, 2022 / nebel / 0 Comments

The featured image of this post is by WikiImages on Pixabay

You want to make a single step in your program, but the debugger takes you to some unknown area of the program. This was, in fact, my first experience when I tried out Microchip’s MPLAB X IDE debugger on the innocent blinking sketch. Is this a bug or a feature?

dw-link: A New Hardware Debugger for ATtinys and Small ATmegas

December 31, 2021 / nebel / 2 Comments

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.

Surprise, Surprise!

December 29, 2021 / nebel / 2 Comments

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.

Debugging a Debugger With Itself

December 27, 2021 / nebel / 0 Comments

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.

Link-Time Optimization and Debugging of Object-Oriented Programs on AVR MCUs

December 15, 2021 / nebel / 0 Comments

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.

Debugging(4): Stub it out!

July 22, 2021 / nebel / 0 Comments

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).

Debugging(3): Debugging is Like Being the Detective in a Crime Movie Where You are Also the Murderer

July 19, 2021 / nebel / 0 Comments

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.

I’m Sorry, Dave, I Can’t do That

July 13, 2021 / nebel / 0 Comments

The featured image of this blog post has been created by Cryteria, CC BY 3.0, Link

Gdb, the GNU debugger, is probably the most used open source debugger for embedded systems. The AVR version of GDB on the Mac is unfortunately not very cooperative. If you try to read an elf file, you get the following funny message (reminding us of HAL9000):

I’m sorry, Dave, I can’t do that. Symbol format `elf32-avr’ unknown.

But with the right homebrew formula, one can teach GDB some new tricks …

EDIT: The problem has been solved by the homebrew maintainers.