SAM7X256_14 Datasheet, PDF (414/662 Pages) ATMEL Corporation – ARM-based Flash MCU

To prevent overwriting the PWM_CUPDx by software, the user can use status events in order to synchronize his
software. Two methods are possible. In both, the user must enable the dedicated interrupt in PWM_IER at PWM
Controller level.
The first method (polling method) consists of reading the relevant status bit in PWM_ISR Register according to the
enabled channel(s). See Figure 33-7.
The second method uses an Interrupt Service Routine associated with the PWM channel.
Note: Reading the PWM_ISR register automatically clears CHIDx flags.
Figure 33-7. Polling Method
PWM_ISR Read
Acknowledgement and clear previous register state
Writing in CPD field
Update of the Period or Duty Cycle
CHIDx = 1
YES
Writing in PWM_CUPDx
The last write has been taken into account
Note: Polarity and alignment can be modified only when the channel is disabled.
33.5.3.4 Interrupts
Depending on the interrupt mask in the PWM_IMR register, an interrupt is generated at the end of the corresponding
channel period. The interrupt remains active until a read operation in the PWM_ISR register occurs.
A channel interrupt is enabled by setting the corresponding bit in the PWM_IER register. A channel interrupt is disabled
by setting the corresponding bit in the PWM_IDR register.
SAM7X Series [DATASHEET]
6120K–ATARM–11-Feb-14
414