https://github.com/SpenceKonde/megaTinyCore Download the core or sync github repo into your (sketchbook)/hardware folder: https://github.com/SpenceKonde/megaTinyCore/archive/v1.0.0_manual.zip.zip
The new megaAVR 1-series and 0-series ATtiny parts bring exciting new features to the ATtiny family. However, until now there has been no support for these parts on the Arduino IDE. This core provides Arduino IDE support for these new parts. This is the initial release, and we expect issues to come up, however, basic functionality is there, with support for the entire ATtiny 1-series and 0-series product line. Please alert us to any issues you encounter with the core.
These parts cannot be programmed via ISP - only via UPDI. An Arduino can be easily made into a UPDI programmer, see: https://github.com/SpenceKonde/megaTinyCore/blob/master/MakeUPDIProgrammer.md
Some of the exciting features: Flash up to 32k, SRAM up to 2k. 5 to 21 usable I/O pins. Runs from internal oscillator, with sufficient accuracy for UART (no crystal support) - core supports 20MHz, 16MHz, 10MHz, 8MHz, 5MHz, 4MHz and 1MHz. Up to 8 PWM pins, hardware UART, SPI, and I2C peripherals, on-chip DAC (core support coming soon), and more.
See the README and part specific pages for more information, and the relevant datasheet for much more detail.
24-pin (21 I/O pins) 3217, 1617, 817, 1607, 807 20-pin (17 I/O pins) 3216,1616, 816, 416, 1606, 806, 406 14-pin (11 I/O pins) 1614, 814, 414, 214, 804, 404, 204 8-pin (5 I/O pins) 412,212,402,202
This core requires the Arduino Official megaAVR board package to be installed (the one with Uno WiFi Rev. 2). This is the version for board manager installation.
Try it out, kick the tires, find the bugs we missed, and create github issues and/or post in this thread. Be sure to read the readme, which lists several known issues