For the past 12 or so years, the AT86RF23x 802.15.4 radios have been my go-to for low-power digital communication. They work pretty well, and I have a good software stack and protocols built up around them (which my friends decided should be called “Bri-Fi.”)

They’re sort of expensive, though—the bare chips are a few dollars each and modules were at least $20-30 last I looked. On a fully custom sensor board they’re not that bad, but for random side projects where I just want two things to talk to each other wirelessly, the cost of the chips and doing an RF layout are kind of annoying.

I’ve been seeing a lot of Nordic’s nRF24L01+ radios in the maker community. It seems there’s a pretty good Arduino library and the modules are available super cheap. I think I got five complete modules for about what I’d pay for one of the RF233 chips.

Anyway, I’m playing around with these modules and put together a couple of quick PCBs to try them out. I’ve been getting pretty good results milling boards at home using my little CNC router, so I thought I’d snap a few photos and write a “quick” blog post. This board is a little USB-to-RF bridge based around the ATmega32U2. If this works, it’s going to be the computer side of a custom user input device.

Last week, lightning struck at Tidmarsh, the former cranberry bog where I’m conducting experiments for my Ph.D. research on sensor networks. We’ve had some nearby lightning strikes before that have caused some minor equipment damage (it’s one of the perils of working in this environment) but nothing quite so major as this. We have some protection against lightning—perhaps not as much as we should have, but it can be quite challenging when we have many cables extending out over a large area.

I was actually there on site when it happened, making myself a cup of tea in the guesthouse. I was looking the wrong way to see the actual bolt, but saw a flash and heard the thunder instantaneously, so that must have been it.

We lost pretty much the entire audio installation at the former impoundment. Closer examination of the damaged equipment tells the story of the path the current took.

I don’t think anything was hit directly, or the damage would have been even more extensive. Most likely, the lightning hit the ground very close to where one of our cameras is out in the marsh. That traveled about 150 meters through a CAT6 ethernet line, into port 4 on the switch in the south box:

For one of my home desktop setups, I have very particular keyboard requirements. Since I put the keyboard in my lap (there’s no desk/table, the monitor is suspended on a cantilevered arm) the pointing device needs to be integrated into the keyboard itself. I’ve become less of a fan of trackpads over the years, especially the terrible ones that are integrated into cheap wireless keyboard combos like the ubiquitous Logitech K400. Furthermore, as it’s a Linux machine and I’m very accustomed to the X11 clipboard, which uses the middle mouse button to paste, I want a physical middle button. I’ve only found one wireless keyboard that meets those requirements, and it’s Lenovo’s bluetooth keyboard with a TrackPoint:

I like the keyboards and TrackPoints on my ThinkPads, so it’s nice to have the same setup. Unfortunately, the wireless keyboard is a bit of a regression from the ones on my ThinkPads: it lacks the row above the function keys, the function keys have tiny markings with big icons for their secondary functions (which I don’t care about) and the build quality is overall not as good as older ThinkPads. I also don’t like Bluetooth (pairing is complicated, and it doesn’t work in the bootloader/BIOS). But, it works. Well, it did, at least until my TrackPoint stopped working one day. The keyboard continued to work, but the TrackPoint started drifting incessantly to the upper left no matter how it was deflected, followed by ceasing to work altogether (including the buttons) a couple of days later.