Internal Clock Source

The Timer/Counter can be clocked directly by the system clock (by setting the CSn2:0 = 1). This provides the fastest operation, with a maximum Timer/Counter clock frequency equal to system clock frequency (f_{CLK_I/O}). Alternatively, one of four taps from the prescaler can be used as a clock source. The prescaled clock has a frequency of either f_{CLK_I/O}/8, f_{CLK_I/O}/64, f_{CLK_I/O}/256, or f_{CLK_I/O}/1024.