How come I can't find the Trinket Serial (COM) Port? Why is no Serial port found when the Trinket is plugged in?

Trinket (and Pro Trinket) do not have a USB-serial converter chip on board, this is how we can make them so small! Instead of a serial console, the Trinket is programmed directly over USB. No COM/Serial port is used at all!

I'd like to use Trinket with Linux....
We don't guarantee Linux support since Linux varies from distro to distro, but here's a very nice tutorial about Trinket with Ubuntu 14)
I can't seem to upload to my Trinket when it's plugged into a USB 3.0 port (newer Macbooks have USB 3 ports)
Trinket's bootloader is finicky about USB 3 ports, and might not work on them. Try connecting to any USB 2 ports you have or go through a USB 1 or USB 2 hub (nearly all hubs are v2 or v1 instead of v3)
My Trinket 16MHz can't control servos, NeoPixels, but the code is uploading OK?

Sounds like the Trinket thinks its running at 8MHz but the Arduino software thinks it's running at 16MHz, this causes timing-specific stuff like Servos and NeoPixels to not work. Don't forget you must turn on 16MHz speedup if you are uploading to "Trinket 16MHz"

Do so by adding

#include <avr/power.h>

At the very top of your sketch, and then

if (F_CPU == 16000000) clock_prescale_set(clock_div_1);

first thing in setup()

See more details here

Hmm I'm still having problems with Avrdude - and I definitely did the required updates

One fix that works for some people is to edit avrdude.conf and set the

chip_erase_delay = 900000;

under the ATtiny85 heading to

chip_erase_delay = 400000;

That is, a shorter delay.

Can Trinket driver Neopixels (strips, squares, etc)? How many?
Yes! Trinket was designed to drive short segments of NeoPixels. There is enough RAM on the attiny85 to drive 100 pixels, but depending on program RAM usage you may have to scale back to 60 or 40.

You can use EITHER the 3V or 5V Trinket, at EITHER 8 or 16MHz!

To use with neopixels:
  1. Connect the + power line of the strip to VBUS (5V from USB), to VBAT if you are powering the Trinket with 4-7VDC, or to a separate 4-7VDC power source such as a 3 or 4 pack of AA batteries.
  2. Connect the - common ground to the battery pack (if being used) and also to the Trinket GND pin
  3. Connect the data in line to Trinket #1 - this will let you also see when data is being sent because the #1 red LED will flicker. You can use other pins but start with #1 since its easiest to debug and use
  4. Install the NeoPixel library as detailed in our Uber Guide, and change the PIN to 1 (its 6 by default)
  5. Upload and enjoy!
Can the Trinket drive your Adafruit I2C LED Backpacks for 7-segment/matrix displays?
Short answer: yes! Check out for a tutorial on driving the 7-segment displays. Long answer: we think there's not enough space for all of the fonts for the 8x8 so you might be able to drive the 8x8 matrix in 'raw' mode (see the HT16K33 example sketch in the LEDBackpack Library) but unfortunately not with built-in font support.

That tutorial also shows how to use the TinyM I2C driver, which works great on the ATtiny85, and adapt other existing libraries for the Trinket
Can Trinket drive a Servo?
Yup! In fact you can use 3 servos as long as they are powered by a good 5V supply, check out this guide for more details
Why does Windows sound the Connect/Disconnect chimes every ten seconds?
The Trinket only appears to be a USBtinyISP device when the bootloader is running. By design, the bootloader only runs for 10 seconds and then jumps back to the main user sketch. this causes the 'disconnect' sound.

On a new trinket, the main sketch will automatically jump back to the bootloader, which will then cause the 'connect' sound. This cycle will repeat until a user sketch is loaded.

This situation can also happen if you load a sketch with a bug in it that causes a CPU reset.
Can I power the directly on the 5.0V or 3.3V (e.g. treating those as a power input)?

Technically yes - you can provide regulated 5V or 3.3V directly to the lower right hand power pin. However, the regulator dropout is quite low, its safer and better to power the VBAT pin since that way you wont be 'fighting' the USB port if you plug in USB

This guide was first published on Sep 03, 2013. It was last updated on Mar 08, 2024.

This page (FAQ) was last updated on Mar 08, 2024.

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