So it's great once you've finished up a prototype on an official Arduino UNO and want to make the project smaller. The Pro Trinket PCB measures only 1.5' x 0.7' x 0.2' (without headers) but packs the same capability as an Arduino UNO. We also added Optiboot support, so you can either program your Pro Trinket over USB or with a FTDI cable just like the Pro Mini and friends. Like the Trinket, it has onboard USB bootloading support - we opted for a MicroUSB jack this time. That's why we designed Pro Trinket, with 18 GPIO, 2 extra analog inputs, 28K of flash, and 2K of RAM. Trinket's a year old now, and while its been great to see tons of tiny projects, sometimes you just need more pins, more FLASH, and more RAM.

It's like an Arduino Pro Mini with more pins and USB tossed in. Trinket's got a big sister in town - the Pro Trinket 3V! Pro Trinket combines everything you love about Trinket with the familiarity of the core Arduino chip, the ATmega328. All have built-in USB and are comparable in price! The ItsyBitsy's especially are about the same size and have native USB and tons of pins, so they're a very close compatible.

Please check out the Metro Mini (ATmega328 5V 16 MHz), ItsyBitsy 32u4 5V 16MHz, ItsyBitsy 32u4 3.3V 8MHz or ItsyBitsy M0 3V 48MHz. So while we still carry the Pro Trinket so that people can maintain some older projets, we no longer recommend it. Deprecation Warning: The Pro Trinket bit-bang USB technique it uses doesn't work as well as it did in 2014, many modern computers won't work well.

Adafruit trinket 5v oins