16.5 Functional Description
16.5.1
Waveform Cycles
The waveform generated by PSC can be described as a sequence of two waveforms.
The first waveform is relative to PSCOUTn0 output and part A of PSC. The part of this waveform
is sub-cycle A in the following figure.
The second waveform is relative to PSCOUTn1 output and part B of PSC. The part of this wave-
form is sub-cycle B in the following figure.
The complete waveform is ended with the end of sub-cycle B. It means at the end of waveform
B.
Figure 16-4. Cycle Presentation in 1, 2 & 4 Ramp Mode
PSC Cycle
Sub-Cycle A
Sub-Cycle B
4 Ramp Mode
Ramp A0
Ramp A1
Ramp B0
Ramp B1
2 Ramp Mode
Ramp A
Ramp B
1 Ramp Mode
UPDATE
Figure 16-5. Cycle Presentation in Centered Mode
PSC Cycle
Centered Mode
UPDATE
Ramps illustrate the output of the PSC counter included in the waveform generators. Centered
Mode is like a one ramp mode which count down up and down.
Notice that the update of a new set of values is done regardless of ramp Mode at the top of the
last ramp.
134
AT90PWM2/3/2B/3B
4317J–AVR–08/10
ATMEL [ ATMEL ]
