Datasheet

SAM3X / SAM3A [DATASHEET]
Atmel-11057C-ATARM-SAM3X-SAM3A-Datasheet_23-Mar-15
970
38. Pulse Width Modulation (PWM)
38.1 Description
The PWM macrocell controls 8 channels independently. Each channel controls two complementary square output
waveforms. Characteristics of the output waveforms such as period, duty-cycle, polarity and dead-times (also
called dead-bands or non-overlapping times) are configured through the user interface. Each channel selects and
uses one of the clocks provided by the clock generator. The clock generator provides several clocks resulting from
the division of the PWM master clock (MCK).
All PWM macrocell accesses are made through registers mapped on the peripheral bus. All channels integrate a
double buffering system in order to prevent an unexpected output waveform while modifying the period, the duty-
cycle or the dead-times.
Channels can be linked together as synchronous channels to be able to update their duty-cycle or dead-times at
the same time.
The update of duty-cycles of synchronous channels can be performed by the Peripheral DMA Controller Channel
(PDC) which offers buffer transfer without processor Intervention.
The PWM macrocell provides 8 independent comparison units capable of comparing a programmed value to the
counter of the synchronous channels (counter of channel 0). These comparisons are intended to generate
software interrupts, to trigger pulses on the 2 independent event lines (in order to synchronize ADC conversions
with a lot of flexibility independently of the PWM outputs), and to trigger PDC transfer requests.
The PWM outputs can be overridden synchronously or asynchronously to their channel counter.
The PWM block provides a fault protection mechanism with 6 fault inputs, capable of detecting a fault condition
and to override the PWM outputs asynchronously.
For safety usage, some control registers are write-protected.