Well, I’m beginning to wonder whether this thing has a bootloader on it. Just tried it with an FTDI board, and depending on which way I arrange the RX/TX pins, I get either a complete hang and a data light that’s perpetually on, or an error stk500_recv(); programmer is not responding. Reset never seems to trip, or rather, it probably does, but the LED flashing just starts right back up afterward with no delay.
So, I thought I’d try the ArduinoISP stuff and see if I could get a loader on there. Unfortunately, the Leonardo platform seems to have some problems with it. MISO, MOSI, and SCK have been moved off of the usual pins and isolated in the ISP header. This isn’t a deal breaker, since I can run them out from there. I’ve redefined reset in the sketch to use pin 10 instead of pin SS. This all should work in theory, but there appears to still be some problem with the process, since avrdude keeps seeing different device signatures on the chip. (Further, trying this with a separate, fresh ATMega on a breadboard achieves the same result, so I’m assuming that this is a problem with my ISP programming and not with the chip or the board.)
At home I have a FutureTech TTL adapter, which maybe I could use to bit-bang the loader in through the ISP connection, so Google tells me. Haven’t tried actually using it yet, though, and who knows? I’m not having the best of luck with this so far. Any other ideas?