at91sam9263 ATMEL Corporation, at91sam9263 Datasheet - Page 716

• Manufacturer Part Number: at91sam9263
• Description: At91 Arm Thumb Microcontrollers
• Manufacturer: ATMEL Corporation

38.5.2
38.5.2.1
Figure 38-3. Functional View of the Channel Block Diagram
38.5.2.2
716
AT91SAM9263 Preliminary
PWM Channel
Block Diagram
inputs from
Waveform Properties
from clock
generator
APB bus
inputs
Channel
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.
Each of the 4 channels is composed of three blocks:
The different properties of output waveforms are:
Selector
Clock
• 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
• the internal clock selection. The internal channel counter is clocked by one of the clocks
• the waveform period. This channel parameter is defined in the CPRD field of the
Section 38.5.1 “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.
provided by the clock generator described in the previous section. This channel parameter is
defined in the CPRE field of the PWM_CMRx register. This field is reset at 0.
PWM_CPRDx register.
- If the waveform is left aligned, then the output waveform period depends on the counter
source clock and can be calculated:
By using the Master Clock (MCK) divided by an X given prescaler value
(with X being 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, or 1024), the resulting period formula
will be:
By using a Master Clock divided by one of both DIVA or DIVB divider, the formula becomes,
respectively:
(
------------------------------ -
X CPRD
×
MCK
)
Counter
Internal
Comparator
715.
PWMx output waveform
6249D–ATARM–20-Dec-07