Thursday, May 31, 2012


When I followup on a past project about which I've written, I always face the quandary whether to update the original article or write a new one. Neither is a perfect solution. The former means folks who have bookmarked that article for future reference or folks finding the article for the first time via a search engine will see the new material. The latter means folks using an RSS feed will see the update. I tend to choose the former, updating the article, and if the update is separated from the original by a long time, I date stamp the new material so as to not confuse the elderly (like me). But to accommodate the folks who depend on their RSS reader, here's some articles I've recently updated.

The C++ Pointer to Member Operators: Based on feedback from readers, I added a short paragraph at the end to explain why one would want to use these operators. These operators, which really don't use pointers to an object but instead offsets into a class, are better than the most likely alternative.

Small Town Big City: I added a section at the end on running Amigo, my FreeRTOS-based interrupt-driven multitasking platform written in C++, to an Arduino Mega ADK with an Ethernet shield and a FreeRTOS EtherTen Uno-clone. Yes, I got a multitasking system running on the ATmega328p-based EtherTen with it's severe resource constraints. It wasn't pretty. I don't recommend it. Co-routines or state machines are likely to be a better solution; they are less scalable, and probably more expensive in the long-run to maintain, but scalability isn't likely to be an issue for the tiny ATmega328p with it's scant two kilobytes of SRAM.

Sunshine On My Arduino Makes Me Happy: I've documented several additional iterations on my solar powered Arduino Uno. The latest version uses a solar charge regulator and a sealed 12V gel cell battery in addition to the solar panel. I'm skeptical that my small battery and solar panel (I definitely went the inexpensive route) are sufficient to keep this system running indefinitely, particularly when the solar panel is just sitting in a south-facing window. But so far it's has run for the past nineteen hours, since about 14:00MDT yesterday. And Colorado has more sunny days than any other state in the Union. Sorry, California.

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