Rainbow Electronics AT91CAP9S250A User Manual
Page 747
747
6264A–CAP–21-May-07
AT91CAP9S500A/AT91CAP9S250A
Figure 40-6. Synchronized Period or Duty Cycle Update
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 ded-
icated interrupt in PWM_IER at PWM Controller level.
The first method (polling method) consists of reading the relevant status bit in PWM_ISR Reg-
ister according to the enabled channel(s). See
.
The second method uses an Interrupt Service Routine associated with the PWM channel.
Note:
Reading the PWM_ISR register automatically clears CHIDx flags.
Figure 40-7. Polling Method
Note:
Polarity and alignment can be modified only when the channel is disabled.
PWM_CUPDx Value
PWM_CPRDx
PWM_CDTYx
End of Cycle
PWM_CMRx. CPD
User's Writing
1
0
Writing in PWM_CUPDx
The last write has been taken into account
CHIDx = 1
Writing in CPD field
Update of the Period or Duty Cycle
PWM_ISR Read
Acknowledgement and clear previous register state
YES