Repairing Bootloader - adafruit learning system Trinket Introduction Manual

Repairing bootloader

The ATtiny85 does not have a protected-bootloader section. This means its possible to
accidentally overwrite the bootloader (or even if you unplug the Trinket while uploading it
might have difficulties from then on)
You can use an Arduino UNO to re-program the bootloader onto your Trinket (or Gemma).
This loader isn't tested to work with any other kind of Arduino.
Connect:
Trinket VBAT+ pin to Arduino 5V (or just power it via a battery or USB cable)
Trinket GND pin to Arduino GND
Trinket RST to Arduino #10
Trinket #0 pin to Arduino #11
Trinket #1 pin to Arduino #12
Trinket #2 pin to Arduino #13
On a Gemma, alligator clips work well. the Reset pin is underneath the MiniUSB Jack. You
may have to solder a wire temporarily. Alternatively, sometimes you can just hold the reset
button down while running the sketch (type 'G' to start) and it might work. Soldering a wire
works best.
Then download, uncompress and run the Trinketloader sketch:
Open up the serial console at 9600 baud and when it tells you do, press the miniature button
on the Trinket (or Gemma) or type in G into the serial console and click Send
You should see the following, the fuses, firmware burned and verified! It will take 2 seconds
© Adafruit
Industries
trinketloader.zip
http://adafru.it/cRF
https://learn.adafruit.com/introducing-trinket Page 42 of 48