After a moderate amount of hacking, I managed to get the arduino software (version 12) to function on my FreeBSD laptop. I connected the Sanguino (which sat there happily blinking its debug LED) via USB/TTL cable and tried uploading some of the example sketches, such as Blink and BlinkWithoutDelay modified to output on pin 1, which I believe the sanguino's debug LED is connected to. With every single sketch, even if I change the output pin to one not connected to anything, the debug LED blinks rapidly at a low brightness, then at a high brightness, and then dies (in total encompossing maybe a quarter of a second) until it is reset, at which point it goes through the normal bootloader blink sequence and then remains dark.

I happen to have a USBtiny AVR ISP handy, and am able to successfully program the AVR and play with the debug LED through that, so the basic functionality of the chip and board is intact. Any thoughts as to what's going wrong, and how to fix it?

Uh, scratch this question. This is embarassing. I didn't check where the arduino software begins counting pins, and was using pin '1' (physical pin 2) instead of pin '0' (physical pin 1); turns out everything works fine.

haha. i had the same thing when i built up my sanguino yesterday. the sanguino page was even down for about 20 minutes (the exact 20 minutes when i was trying to look it up).

of course i also had the issue at first that i forgot about the USB/EXT power switch was switched to EXT. though the green LED lit (at least dimly) when i hooked up my FTDI cable, it wouldn't transfer the sketch.

ho hum. my assembly went well though and it works.