ZigFlea board available

I am happy to announce that the ZigFlea board is currently available from Seedstudio. This board is the result of the Master’s thesis of Øyvind Hauback, whom I co-supervised at fourMs. The main point of the board is to provide an easy way of using ZigBee wireless communication together with Dan Overholt’s CUI32Stem sensor interface.

The ZigFlea wireless board
The ZigFlea wireless board, as sold from Seedstudio.

The board is described in Øyvind’s thesis (in Norwegian), as well as in short form (and English) in our NIME 2012 paper. Here are the technical details, taken from the Seedstudio web page:

Based on the Freescale MC13201 transceiver, which supports the IEEE 802.15.4 standard used by ZigBee and ZigFlea. Serial Peripheral Interface (SPI) pins are provided as standard, with the layout matching the CUI32Stem pin locations. The transceiver runs at 2.4 GHz and has support for 16 channels and a speed of up to 250 Kbps.

ZigFlea is a subset of the ZigBee protocol, as implemented in StickOS. It equals ZigBee regarding the physical layer, but is a point-to-point protocol focused on sending in only one direction at a time (half-duplex). The benefit of this is that the protocol stack is as little as 3 KB, as compared to the 30 KB for ZigBee (which includes multiple hops and other features).

The board is open hardware, so the schematic and layout files are freely available.

Force eject a stuck DVD

What to do when a DVD is stuck in the drive on an old iMac, and it refuses to booth up? There are numerous ways of doing this, including:

  • Start up while holding down the mouse button.
  • Start up while holding down the Option key, then hit the eject button.
  • Start up while holding down Command-Option-O-F, to enter the Open Firmware prompt, then type “eject cd”.
  • Start up while holding down Command-S to enter recovery mode.

Unfortunately, none of these worked. Finally, I found a tip about just physically stopping the DVD from spinning up during boot. So I tried sliding a few yellow note-it stickers inside of the DVD drive. This nicely prevented the drive from spinning up, so that the regular boot procedure could continue. Sometimes a mechanical solution is the best.

Unnecessary long cables

Working with music technology I am used to cables. I don’t mind the cables themselves, since cables are in general much less pain than slow/unreliable wireless solutions. However, I do mind unnecessary long cables. Therefore I love the MacBook power adapters (which are even better in US version than the EU).

I also love the retractable iPhone cables and short USB cables (which even works with my small USB-powered hard drives) they sell on Dealextreme, which make my setup very cable-friendly:

Unfortunately, I have yet to find short power cables. For example, I have one adapter with a small, thin cable on one side, but with a monster of a power cable on the other side:

I have been looking for a short replacement cable (this particular being of the Mickey Mouse type, but I would need for regular AC adapters as well). Unfortunately, it seems like 1 meter (or longer) is some kind of standard size for such cables.  I want some really short cables, ideally something just like the Apple plugs, but something more generic-looking and fitting the various types of connectors that exist:

I could even dom with something like what they have at Cables online, but with a European plug:

Please let me know if you know where to get such short cables (with EU plug). Otherwise, I will have to get my soldering iron out…

Headset for Mac

I have seen/heard several questions about what type of headset to use for skyping on MacBooks over the last few days. Here are my suggestions:

USB headset: Since MacBooks do not come with a separate microphone input (only line level input), regular PC headsets with two mini-jack cables won’t work. I have good experience using USB headsets from Logitech. I have a couple of 250s, but since one of them broke during travel I also got a more durable H555. The latter is nice, since the actual headset can be physically removed from the USB sound card (a small dongle). This means that the sound card can be used with a different headset (or microphone). As such, it serves the same purpose as a small dedicated sound card like the iMic.

iPhone headset: It was only fairly recently that I discovered that newer MacBooks sport a 4-pin minijack connector. A regular stereo minijack has three pins (2 channels + ground), while the 4-pin connectors can also carry a microphone signal. This is the type of connector that is used in the iPhone headsets, which also means that your favourite iPhone headset can be used for skyping on the MacBook. After I discovered this I have no longer bothered bringing my USB headset around when travelling.

Built-in microphone: My experience is also that the built-in microphone and speakers on the MacBook actually work very well for skyping. I have had remarkably few feedback issues with my latest MacBook, so they have done some smart engineering to remove feedback problems in different parts of the chain. The only problem is that the microphone tends to pick up key strokes etc. very easily, so if you want to use your computer while skyping it is not the best way of doing things.

Conference microphone: When using Skype for more conference type of calls, i.e. where several people are supposed to be picked up, I use a small conference microphone ATR97 from Audio-Technica to get a better result. This I connect to the USB dongle of the Logitech H555 mentioned above, or my iMic. The only negative thing about the ATR97 is that I tend to forget to turn it off after use, so that the battery drains out.

Professional microphones: Of course, for the best sound quality it is possible to use a larger sound card and high quality microphone also for skyping. In my office I currently have a AKG GN 30 swan neck microphone connected to a Alesis MultiMix 4 USB mixer. The mixer plugs directly into the MacBook, and also gives access to simple adjustments of the frequency bands.

All in all, there are a great many different ways of getting sound into your computer, dependent on the situation, the quality needed and how much gear you want to carry around.