13.24.6.2.5.5 Single-Slope PWM Operation

For single-slope PWM generation, the period time (T) is controlled by Top value, and CCx controls the duty cycle of the generated waveform output. When up-counting, the WO[x] is set at start or compare match between the COUNT and TOP values, and cleared on compare match between COUNT and CCx register values. When down-counting, the WO[x] is cleared at start or compare match between the COUNT and ZERO values, and set on compare match between COUNT and CCx register values.

Figure 13-142. Single-Slope PWM Operation

The following equation calculates the exact resolution for a single-slope PWM (R_{PWM_SS}) waveform: 

R_{PWM_SS} = \frac{log(TOP+1)}{log(2)}

The PWM frequency depends on the Period register value (PER) and the peripheral clock frequency (f_{GCLK_TCC}), and can be calculated by the following equation:

f_{PWM_SS} = \frac{f_{GCLK_TCC}}{N(TOP+1)}

Where N represents the prescaler divider used (1, 2, 4, 8, 16, 64, 256, 1024).