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.