Evan - Install the ATTTinyCore Board Support Package by Spence Konde,
The "Additional Boards Manager URL" is???
The package supports the Digispark with the ATTiny85.
Recommend also setting the clock frequency to 8 MHz, for in-spec operation of the ATTiny85 at 3.3 Volts.
There are over 50 messages captured on this topic here on the forum under the topic "swr_bridge.ino"
73; Steve, N3SB
