The initial tests so far have been good. I needed to check:

• That the ATTiny85 could run at 16MHz on 3,3V - OK
• The accuracy of the internal oscillator - OK

The accuracy was no so good as the measured frequency was 16.1MHz, but it is always possible to trim this later using a given EEPROM address that is loaded on the OSCCAL register on the beginning of the code.

It is necessary to program the fuses accordingly and to attach the scope at pin 3 to check the frequency.

Of course it is possible to use other methods that do not involve reprogramming of fuse bits.