Is there any new insight or information about why the new Macs don't consistently work with the USBtinyISP? I had a 2010 MacBook Pro that seemed to work reliably with my USBtinyISP. Over the summer I upgraded to a MacBook Pro with Retina display, and now it seems to fail 4 out of every 5 times I run avrdude, with the basic rc=-1 error.
I'm trying to upload a simple "Hello World" program to an ATtiny13 running at 128KHz. It generally works fine the first time, then I make changes to the code and try to upload the new version and I get the failure below. I try unplugging and replugging the USB cable, moving it to the computer's other USB3 port, etc, but the only thing that seems to work is waiting a few minutes. And sometimes that doesn't work either. Since I'm running at 128KHz, I've also tried using slower speeds, as high as -B 250, but that doesn't seem to work any more reliably than -B 32.
I've tried with two different USB cables and both work equally often. Today I bought a USB 2.0 hub hoping that would fix the problem, but same thing - it worked the very first time (thrilling!), but then failed when I tried again a minute later. In all cases, the USBtiny provides power to the ATtiny and the ATtiny keeps running its program correctly. As usual with a Mac, the green LED on the USBtiny is initially off but turns on the first time I run AVRdude after plugging it in.
I'm running OS X 10.8.2 on an 2.6 GHz Intel Core i7 with 16 GB 1600 MHz DDR3 ram. (I didn't realize until re-reading this thread that the USB hub was suppose to be powered, the one I found is bus-powered, so maybe that's a possible fix? But why is any of this necessary?)
Are USB 3 ports much more finicky about working with USB 1 devices? Do I need to find an old USB 1 hub that plugs into an outlet? Or just keep rebooting my Mac and trying different USB cables? And should I be looking for new or old USB cables? Is there a possible update to the USBtiny firmware?
Thanks for any advice or tips!
avrdude -c usbtiny -p attiny13 -B 32 -U flash:w:main.hex:i
avrdude: initialization failed, rc=-1
Double check connections and try again, or use -F to override
avrdude done. Thank you.
make: *** [flash] Error 1