Datasheet

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, pick the one that matches your

Arduino version!

trinketloader_2015-06-09.zip

http://adafru.it/fmg

Uncompress and open in the Arduino IDE, select the UNO and serial port to the UNO Arduino board

you are uploading too and upload it to the UNO.

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

Industries

https://learn.adafruit.com/introducing-trinket Page 58 of 65