Gumstix: my early experience

I've played with several microcontrollers over the years but I've been especially excited about the opportunity to try the Gumstix line

for quite awhile. Unlike the EVBs I've tried over the years, these are fairly full-fledged ready-to-go computers in small packages. They run Linux and have end-user I/O (like line-level audio and Bluetooth).

My wife needs some cockpit voice recorders so I recently looked around for a good solution. The Gumstix seemed like a fine place to start. Its support of an MMC card ensured that I could store several hours of compressed audio and its low power requirements should allow me to easily run it off of a battery, even for overnight trips.

There are lots of things I've dreamed of doing with Gumstix so I got the 400ax-bt waysmall computer and an Audiostix. The CPU module has Bluetooth and a 400MHz CPU. I don't plan to need those for this project but I wanted to experiment with the full capabilities.

Out of the box the waysmall has two serial interfaces. I connected one to my computer and got a bootloader prompt when I applied power. It booted without issue and I was able to log on over the serial port.

I don't have an RS-232 port on the tablet computer I'm using these days so I decided to try the Bluetooth. It worked right off the bat! I was surprised. It works well at ~30'. It turns out that the Bluetooth is also handy because I have to swap out the serial ports for the Audiostix. (I could also use the USB interface but I'd have to locate my cable...)

So, once I verified that things worked I tried the Audiostix. This was the first failure. There doesn't seem to be support for it in the shipped (non-modular) kernel. This forced me to start compiling my own root filesystem.

As a first attempt I tried the latest Subversion-maintained version. The installation went well but it failed while booting once and yielded lots of Bluetooth errors. Although it seemed to be able to perform a Bluetooth scan, I was unable to connect with it. I wanted to get back to a known good situation so I downloaded the r162 rootfs from Sourceforge. That restored Bluetooth functionality.

Next I decided to try building my own r162. After a minor tweak (to fix the ntp URL), that version installed and worked just like the precompiled one. O.k., now I know I can build something that works.

Now I'm just bumbling around trying different revisions. I hope to hit on one that is robust but also includes audio support. This will take awhile.

--kyler