The featured image of this post is by Emphyrio on Pixabay

In parasitic power supply mode, a device sucks its juice from a data line instead of from the power rail. This can be intended or unintended. In the latter case, all sorts of funny things can happen.

Make it Fail

(David J. Agans)

The quote is from Dave’s book Debugging: the 9 indispensable rules for finding even the most elusive software and hardware problems, which I recommend to everybody who has to debug a technical artifact.

Another xkcd comic that hits the spot. Except, with my new hardware debugger, this is the past 😎. Recently, I debugged one of my electronic geocaching gadgets and was positively surprised how easy it was to figure out ones own mistakes and to come up with the right fix.

The featured image of this post is based on a picture by Florian-if published at Wikipedia under CC-BY-SA-3.0

Is it possible to build a hardware debugger for debugWIRE for less than €10? As it turns out, it is. You just have to make a few compromises and also do a bit of soldering and gluing.

dw-link can turn your Arduino board into a hardware debugger, and dw-probe connects it to any target board.

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?

There has never been an unexpectedly short debugging period in the history of computers

… but the periods might have become shorter with the right tools

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. And 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 still plenty of surprising situations: Split personality MCUs, stuck-at-one bits in program counters, secret I/O addresses, half-legal opcodes, and more.