I would like to know what registers I need to set up to which values and by which order in order to make my ATTiny85 run at maximum possible frequency under 3.3V without a crystal. I'm using the pins of the crystal for something else so I cannot use them.
Also, in case I do need a crystal, how do I connect it to only one XTAL pin and, again, with which register configuration?
I would like to see C code, but if possible without special functions, but only with statements like REGISTER=0x12;. The code needs to be very small.
Would anyone know?