SAM3N00A Atmel Corporation, SAM3N00A Datasheet - Page 631

• Manufacturer Part Number: SAM3N00A
• Manufacturer: Atmel Corporation

32.6.2
32.6.2.1
11011A–ATARM–04-Oct-10
PWM Channel
Block Diagram
Caution: Before using the PWM macrocell, the programmer must first enable the PWM clock in
the Power Management Controller (PMC).
The PWM macrocell master clock, MCK, is divided in the clock generator module to provide dif-
ferent clocks available for all channels. Each channel can independently select one of the
divided clocks.
The clock generator is divided in three blocks:
Each linear divider can independently divide one of the clocks of the modulo n counter. The
selection of the clock to be divided is made according to the PREA (PREB) field of the PWM
Mode register (PWM_MR). The resulting clock clkA (clkB) is the clock selected divided by DIVA
(DIVB) field value in the PWM Mode register (PWM_MR).
After a reset of the PWM controller, DIVA (DIVB) and PREA (PREB) in the PWM Mode register
are set to 0. This implies that after reset clkA (clkB) are turned off.
At reset, all clocks provided by the modulo n counter are turned off except clock “clk”. This situa-
tion is also true when the PWM master clock is turned off through the Power Management
Controller.
Figure 32-3. Functional View of the Channel Block Diagram
Each of the 4 channels is composed of three blocks:
• A clock selector which selects one of the clocks provided by the clock generator described in
• An internal counter clocked by the output of the clock selector. This internal counter is
• A comparator used to generate events according to the internal counter value. It also
inputs from
from clock
generator
APB bus
Section 32.6.1 “PWM Clock Generator” on page
incremented or decremented according to the channel configuration and comparators events.
The size of the internal counter is 16 bits.
computes the PWMx output waveform according to the configuration.
inputs
– a modulo n counter which provides 11 clocks: F
– two linear dividers (1, 1/2, 1/3, ... 1/255) that provide two separate clocks: clkA and
F
clkB
MCK
/16, F
Channel
Selector
Clock
MCK
/32, F
MCK
/64, F
MCK
Counter
Internal
/128, F
MCK
/256, F
630.
MCK
MCK
Comparator
, F
MCK
/512, F
/2, F
MCK
MCK
/1024
/4, F
MCK
/8,
SAM3N
PWMx
output waveform
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