A TinyTerminal for Tiny Messages
Stefan Wagner's USB-controlled device uses an ATtiny85 and 128x64 OLED display to show text.
The serial terminal for Arduino and the like is a fundamental tool for troubleshooting and communication, allowing you to pass messages back and forth between different pieces of hardware. In the case of many boards, this is facilitated by a dedicated onboard chip – like the Arduino Uno’s ATmega16U2. For other devices, such as a bare ATtiny85, communication requires a USB-to-serial cable.
Stefan Wagner's TinyTerminal USB, however, runs on an ATtiny85 and requires no such chip to enable it to receive messages from a computer. You simply plug in a Micro USB cable, and it receives serial messages that are then shown on its 128x64 pixel I2C OLED display. The unit even features an integrated buzzer, which conveniently gives an acoustic signal each time a message is received.
The trick here is that its using V-USB firmware to let the ATtiny85 act as a low-speed USB 1.1 device. While you wouldn’t want to, say, transfer a 4K movie with it, for simple text messages it's more that sufficient. This wiring setup leaves enough pins available to control the OLED, providing a nice little display module that’s looks like a fun diversion.
More info on the design can be found on Wagner's GitHub, as well as his EasyEDA page.