SAM7S256_14 Datasheet, PDF (488/775 Pages) ATMEL Corporation – ARM-based Flash MCU

Figure 34-6. Synchronized Period or Duty Cycle Update
User's Writing
PWM_CUPDx Value
1
0
PWM_CMRx. CPD
PWM_CPRDx
PWM_CDTYx
End of Cycle
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 34-7.
The second method uses an Interrupt Service Routine associated with the PWM channel.
Note: Reading the PWM_ISR register automatically clears CHIDx flags.
Figure 34-7. 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.
SAM7S Series [DATASHEET]
6175M–ATARM–26-Oct-12
488