Frequency (FRQ) Waveform Generation

For frequency generation, the period time (T) is controlled by the TCAn.CMP0 register instead of the Period (TCAn.PER) register. The corresponding waveform generator output is toggled on each compare match between the TCAn.CNT and TCAn.CMPn registers.

Figure 1. Frequency Waveform Generation

The following equation defines the waveform frequency (fFRQ):


where N represents the prescaler divider used (see the CLKSEL bit field in the TCAn.CTRLA register), and fCLK_PER is the peripheral clock frequency.

The maximum frequency of the waveform generated is half of the peripheral clock frequency (fCLK_PER/2) when TCAn.CMP0 is written to 0x0000 and no prescaling is used (N = 1, CLKSEL = 0x0 in TCAn.CTRLA).