I have an Arduino Uno as well as several freeduino boards and some EMSL Atmegaxx8 target boards. I was trying to take the leap from Arduino to AVR programming, and I decided to start flashing sketches directly to my Arduino. I edited the preferences.txt file to use the usbtinyisp and followed directions and when I try to upload a sketch I the get error:
USB write error: expected 128, got -1
avrdude: verification error, first mismatch at byte 0x00ef
0x92 != 0xa9
avrdude: verification error; content mismatch
After I searched for solutions for hours and decided I wasn't ready for the head ache of setting up development outside of Arduino yet and tried to burn the bootloader back I got the same error.
Just to be sure that It wasn't my Uno I tried my other barebones card and the same issues arises...
Incidentally AVRDUDE registers fine and will erase the chips, I just dont have any .hex files to try and upload and as said before developing outside of the Arduino IDE seems nightmarish...
I just dont have any .hex files
Hold the shift key down and verify (not upload) a sketch and it shows where is hex file is. At least in Ubuntu.
Thanks I found where Arduino stores compiled code however, I still get the same error when I use AVRDUDE directly...
What operation system are you running?
I've seen errors like this before with the USBtiny but never figured out what caused them. I would ask on the adafruit forum, they're usually great about providing support.