The Timer/Counter can be clocked directly
by the system clock (by setting the TCCR0B.CS
0[2:0]=0x1). 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.
Figure 1. Prescaler for
Timer/Counter0