25.3.3.2 Waveform Generation Modes

The TCD provides four different Waveform Generation modes controlled by the Waveform Generation Mode (WGMODE) bit field in the Control B (TCDn.CTRLB) register. The Waveform Generation modes are:

One Ramp mode
Two Ramp mode
Four Ramp mode
Dual Slope mode

The Waveform Generation modes determine how the counter is counting during a TCD cycle and how the compare values influence the waveform. A TCD cycle is split into these states:

Dead-time WOA (DTA)
On-time WOA (OTA)
Dead-time WOB (DTB)
On-time WOB (OTB)

The Compare A Set (CMPASET), Compare A Clear (CMPACLR), Compare B Set (CMPBSET), and Compare B Clear (CMPBCLR) compare values define when each state ends and the next begins.