Re-programming Bootloader

If you'd like to reprogram the bootloader on your Pro Trinket, or update the bootloader to not have the Optiboot-loop-on-RX bug, download this zip of two Arduino sketches

These are only tested on an UNO! For non-UNOs you'll need to swap pins 11, 12, 13 for the hardware SPI pins but we haven't tested it at all, so UNO only please.

Load one or the other onto the Uno, depending on which type you are programming, then connect

  • Pro Trinket 13 -> Arduino 13 (Use ~1K series resistor if prog'ing Pro Trinket 3V)
  • Pro Trinket 12 -> Arduino 12
  • Pro Trinket 11 -> Arduino 11 (Use ~1K series resistor if prog'ing Pro Trinket 3V)
  • Pro Trinket GND -> Arduino GND
  • Pro Trinket VBAT -> Arduino 5V
  • Pro Trinket RESET -> Arduino 10 (Use ~1K series resistor if prog'ing Pro Trinket 3V)


open the terminal @ 57600 baud and press G and return (or click Send)

Last updated on 2015-06-09 at 01.44.48 PM Published on 2014-08-20 at 05.12.17 PM